11. Law & Investigation
1. IT
Act 2000 specifies eight acts which if carried out without the permission of
the owner or the person in-charge of a computer system are considered as
crimes. List any three such acts and relate them to the type of security attacks.
[5]
2. What
are the objectives mentioned in the Preamble to the IT Act? [6]
3 State
any four acts amounting to "cybercrime" as per IT Act 2000. [4]
4 What
are the conditions prescribed in IT Act 2000 for the purpose of Electronic Governance
to retain documents, record or information in electronic form for any specified
period? [6]
5 What
are the short comings of IT Act 2000 that deter companies from approaching the
cyber cell for the enforcement? [4]
6 Explain the various measures required
to be taken in Security Testing of a financial institution with respect to IT. [9]
7 List
three penalties related to Cyber crimes from the IT act of India. [4]
8 What is cyber crime and cyber
forensic? [4]
9 Cyber crime may
be broadly classified in three groups. Explain each of them. What precautions
one has to take to prevent cyber crime in the society? [8]
OVERVIEW OF NETWORK SECURITY
1.What is
Encipherment?
Ans :-- The use of mathematical algorithms to
transform data into a form that is not readily intelligible. The transformation
and subsequent recovery of the data depend on an algorithm and zero or more
encryption keys.
2.What are the four
basic tasks in designing a particular security service?
Ans :--
- Design an
algorithm for performing the security-related transformation.
The algorithm should be such that an opponent cannot defeat its
purpose.
- Generate the
secret information to be used with the algorithm.
- Develop methods
for the distribution and sharing of the secret information
- Specify a
protocol to be used by the two principals that makes use of the
security algorithm and the secret information to achieve a
particular security.
3.Define Threats.
Ans :--
Information
access threats intercept or modify data on behalf of users who should not have
access to that data.
Service
threats exploit service flaws in computers to inhibit use by legitimate users.
4.What is the use
of digital signature?
Ans
:-- Data appended to, or a data unit
that allows a recipient of the data unit to prove the source and integrity if
the data unit and protect against forgery.
5.Define security
recovery.
Security recovery deals with requests from mechanisms, such as event
handling and management functions, and takes recovery actions.
6.What are the
aspects of information security?
There are three aspects of the
information security.
Security attack
Security mechanism
Security Service
7.List some common
information integrity functions?
Ans :--
Identification
Authorization
Concurrence
Liability
Endorsement
Validation
Time of occurrence
Registration
8.What is meant by
threat?
Ans :--
A
potential for violation of security, which exists when there is a
circumstances,capability,action or event that could breach security and cause
harm. That is, a threat is a possible danger that might exploit a
vulnerability.
9.What is meant by
attack?
Ans :--
An
attack on system security that derives from an intelligent threat: that is an
intelligent act that is a deliberate attempt(especially in the sense of a
method or technique) to evade security services and violate the security policy
of a system.
10.State some example of security attacks?
Ans :--
1.Gain unauthorized access to
information(ie.violate secrecy or privacy)
2.Disavow responsibility or
liability for information the cheater
did originate.
3.Enlarge cheater’s legitimate license(for access ,origination,
distribution etc).
4.Pervert the function of software,
typically by adding a covert function.
5.Cause others to violate a
protocol by means of introducing incorrect information.
CLASSICAL ENCRYPTION TECHNIQUES
1.What are the essential ingredients of a symmetric cipher?
A symmetric encryption scheme has five
ingredients:
Plaintext: This is the original intelligible message or
data that is fed into the algorithm as input.
Encryption
algorithm: The encryption algorithm
performs various substitutions and transformations on the plaintext.
Secret
Key: The secret key is also input to
the encryption algorithm. The key is the value independent of the plaintext.
The algorithm will produce a different output depending on the specific key
being used at the time. The exact substitutions and transformations performed
by the algorithm depend on the key.
Cipher
text: This is the scrambled message
produced as output. It depends on the plaintext and the key.
Decryption
algorithm: This is essentially the
encryption algorithm in reverse. It takes the cipher text and the secret key
and produces the original plaintext.
2.What are the two
basic functions used in the encryption algorithm?
All the encryption algorithms are
based on two general principles:
Substitution: In which each element in the plaintext(bit,
letter, group of bits or letters) is
mapped into another element.
Transposition: In which elements in the plaintext are
rearranged.
The
fundamental requirement is that no information be lost(that is ,that all
operations are reversible). Most systems, referred to as product systems,
involve multiple stages of substitutions and transpositions.
3.How many keys are
required for two people to communicate via a cipher?
Ans :--
If both sender and receiver use the
same key, the system is referred as symmetric, single-key, secret-key or
conventional encryption. If both sender and receiver uses a different key, the
system is referred as asymmetric, two-key or public key encryption.
4.What is the
difference between a block cipher and a stream cipher?
Ans :--
A block cipher processes
the input one block at a time, producing an output block for each input block.
A stream cipher processes the input
continuously, producing output one element at a time, as it goes alone.
5.What
are the two general approaches to attacking a cipher?
Ans
:--
The general two approaches for attacking a cipher
Cryptanalysis:
Cryptanalytic attacks rely on the
nature of the algorithm plus perhaps some knowledge of the general characteristics
of the plaintext or even some samples plaintext-cipher text pairs. This type of
attack exploits the characteristics of the algorithm to attempt to deduce a
specific plaintext or to deduce the key being used. If the attack succeeds in
deducing the key, the effect is catastrophic: All future and past messages
encrypted with the key are compromised.
Brute-force
attack: The attacker tries every
possible key on a piece of cipher text until an intelligible translation into
plaintext is obtained. On average, half of all possible keys must be tried to
achieve success.
6.List and briefly
define types of cryptanalytic attacks based on what is known to the attacker?
Ans :--
The various types
of cryptanalytic attacks, based on the amount of information known to the
cryptanalyst
Type of attack
Known to cryptanalyst
7.What is the
difference between an unconditionally secure cipher and a computationally
secure cipher?
An encryption scheme is unconditionally secure if the cipher text
generated by the scheme does not contain enough information to determine uniquely
the corresponding plaintext, no matter how much cipher text is available.
An encryption scheme is
said to be computationally secure if:
The
cost of breaking the cipher exceeds the value of the encrypted information.
The
time required to break the cipher exceeds the useful lifetime of the
information.
8.Briefly define the Caesar cipher?
Ans :--
The Caesar cipher involves replacing
each letter of the alphabet with the letter standing three places down the
alphabet .The alphabet is wrapped around, so that the letter following Z is A.
C = E (p) = (p + 3) mod (26)
The
general Caesar cipher algorithm is
C = E (p) = (p + k) mod (26)
where
k takes the value in the range 1 to 25
The
decryption algorithm is
p = D(C) = (C - k) mod (26)
9.Briefly define the monoalphabetic cipher?
Ans :---
A dramatic increase in the key space is achieved by allowing an arbitrary
substitution. There are 26! Possible
keys. It is referred to as monoalphabetic substitution cipher, because a single
cipher alphabet is used per message.
10.Briefly define the Playfair cipher?
Ans :--
The
Playfair cipher treats the digrams in the plaintext as single units and
translates these units into ciphertext digrams. This algorithm is based on the
use of a 5 by 5 matrix of letters constructed using keyword. Consider keyword
as monarchy. The matrix is constructed by filling in the letters of the keyword
from left to right and from top to bottom, and then filling in the remainder of
the matrix with the remaining letters. The letters I, J count as one letter
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M
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O
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N
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A
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R
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C
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H
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Y
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B
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D
|
|
E
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F
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G
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I/J
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K
|
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L
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P
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Q
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S
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T
|
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U
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V
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W
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X
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Z
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The
rules to be followed are:
Repeating
plaintext letters that come in the same pair are separated with a filer letter,
such as x.
Plaintext
letters that fall in the same row are replaced by the letter to the right, with
the first element of the row circularly following the first.
Plaintext
letters that fall in the same column are replaced by the letter beneath,
with the top element circularly following the last.
Otherwise
each letter is replaced by the letter that lies in its own row and the column
occupied by the other plaintext.
11.What is the difference between a
monoalphabetic cipher and a polyalphabetic cipher?
Ans
:-- In monoalphabetic cipher
single cipher alphabet is used per message. But in polyalphabetic cipher there
are multiple ciphertext letters for each plaintext letter, one for each unique
letter of keyword.
12.What are two problems with the one-time pad?
Ans :-
The one- time pad has the following
two fundamental difficulties:
(a)
There
is the practical problem of making large quantities of random keys. Supplying
truly random characters in this volume is a significant task.
(b)
For
every message to be sent, a key of equal length is needed by both sender and
receiver. Thus a mammoth key distribution problem exists.
Block Ciphers and The
Data Encryption Standard
1.Why is it
important to study the Feistel Cipher?
Ans :--
Feistel cipher
using the concept of a product cipher, which is the performing of two
or more basic
ciphers in sequence
in such a
way that the final
result or product is cryptographically stronger then any of the
component ciphers.
Feistel proposed the use
of a cipher that alternates substitutions and permutations. So Feistel cipher
is considered to be an important one.
2.What is the
difference between a block cipher and a stream cipher?
Ans :--
A block cipher process the input one block of elements at a time
producing an output block for each input block.
A stream cipher process
the input elements continuously , producing output one element at a time, as it
goes along.
3.Why is it not
practical to use an arbitrary reversible substitution cipher of the kind shown
in Table.
Ans :--
Encryption and decryptions tables for substitution cipher
|
Plain Text
|
Cipher Text
|
|
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
|
1110
0100
1101
0001
0010
1111
1011
1000
0011
1010
0110
1100
0101
1001
0000
0111
|
|
Cipher Text
|
Plain Text
|
|
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
|
1110
0011
0100
1000
0001
1100
1010
1111
0111
1101
1001
0110
1011
0010
0000
0101
|
In this example the key requires 64 bits. In general, for an n-bit
general substitution block cipher, the size of the key is n*2n. For
a 64-bit block, which is a desirable length to thwart statistical attacks, the
key size is 64*264 = 270 ~ 1021 bits. So it is
not practical to use an arbitrarily reversible substitution cipher.
4.What is product
cipher?
Ans :--
Product cipher has the performance of two or more basic ciphers in
sequence is such a way that the final result or product is cryptographically stronger than any of the
component ciphers.
5.What is the
difference between Diffusion and Confusion?
Ans :--
In Diffusion the
statistical structure of the plaintext is dissipated into long range statistics
of the cipher text. This is achieved by having each plaintext digit affect the
value of many cipher text digits. Which is equivalent to saying that each
cipher text digit is affected by many plaintext digits.
Confusion seeks to make a relationship between the statistics of the cipher text
and the value of the encryption key as complex as possible. Thus even if the
attacker can get some handle on the statistics of the cipher text, the way in
which the key was used to produce that cipher text is so complex as to make it
difficult to deduce the key.
6 .Which parameters and design choices determine the actual algorithm of a Feistel cipher?
Ans :--
Block
size: Larger block sizes mean
greater security but reduced encryption/decryption speed. A block size of 64
bits is a reasonable tradeoff and has
been nearly universal in block cipher design.However, the new AES uses a
128-bit block size.
Key
size:Larger key size means greater
security but may decrease encryption/decryption speed.Key sizes of 64 bits or
less are now widely considered to be inadequate, and 128 bits has ecome a
common size.
Number
of rounds: The essence of the Feistel
cipher is that a single round offers inadequate security but that multiple
rounds offer increasing security.A typical size is 16 rounds.
Subkey
generation algorithm: Greater
complexity in this algorithm should lead to greater difficulty of
cryptanalysis.
Round
function: Again, greater complexity
generally means greater resistance to cryptanalysis.
7. What is the
purpose of the S-boxes in DES?
Ans :--
The role of the S-boxes in the
function F is that the substitution
consists of a set of eight S-boxes ,each of which accepts 6 bits as input and
produces 4 bits as follows: The first and last bits of the input to box Si form
a 2-bit binary number to select one of four substitutions defined by the four
rows in the table for Si.The middle four bits select one of the sixteen
columns.The decimal value in the cell selected by the row and column is then
converted to its 4-bit representation to produce the output. For example, in
S1,for input 011001,the row is 01 and the column is 1100.The value in row
1,column 12 is 9,so the output is 1001.
8. Explain the
avalanche effect?
Ans :--
A desirable
property of any encryption algorithm is that a small change in either the
plaintext or the key should produce a significant change in the ciphertext.In
particular, a change I one of the plaintext or one bit of the key should
produce a change in many bits of the ciphertext.
9. What is the
difference between differential and linear cyptanalysis?
Ans :--
Linear cryptanalysis based on finding linear
approximations to describe the transformations performed in DES
KEY MANAGEMENT:OTHER PUBLIC KEY CRYPTOSYSTEMS
1.What are the two different uses of public-key
cryptography related to key distribution?
Ans
:-- There are two aspects to the
use of public-key cryptography
In this regard:
The distribution of public keys
The use of public-key encryption to
distribution secret
keys
2.List four general categories of schemes for the
distribution of public keys.
Ans :--
Public announcement
Publicly available directory
Public-key authority
Public-key certificates
3.What are the essential ingredients of a public-key
directory?
Ans :--
The authority maintains a directory with a
entry for each participant.
Each participant registers a public key with
the directory authority.
A participant may replace the existing key
with a new one at any time.
Periodically, the authority publishes the
entire directory or updates to the directory.
Participants could also access the directory electronically.
4.What is public-key certificate?
Ans :--
The public-key authority could
be a bottleneck in the system, for a
user must appeal to the
authority for a public key for every other user that it wishes to contact. As before the
directory of names and public keys maintained by the authority is vulnerable to
tempering.
5.What are the requirements for the use of a
public-key certificate scheme?
Ans :--
Any participant can read a certificate to
determine the name and public key of the certificate’s owner.
Any participant can verify that the
certificate originated from the certificate authority and is not counterfeit.
Only the certificate authority can create
and update certificates.
Any participant can verify the currency of
the certificate.
6.Briefly explain Diffie-Hellman key exchange.
Ans
:--
The purpose
for this algorithm is to enable two users to exchange a key securely that can
then be used for subsequent encryption of messages. It depends for its
effectiveness on the difficulty of computing discrete logarithms.
1)What types of
attacks are addressed by message authentication?
Content
modification - Changes to the
contents of the message
Sequence
modification - Any modification to a
sequence of messages between parties, including
insertion, deletion, and reordering.
Timing
modification - Delay or replay of
messages.
2)What two levels
of functionality comprise a message authentication or digital signature
mechanism?
Ans :--
Low-level
authentication
Higher-level
authentication
At the lower level there must be some sort of
function that produces an authenticator: a value to be used to authenticate a
message. This lower level function is then used as primitive in a higher-level
authentication protocol that enables a receiver to verify the authenticity of
message.
3) What are some
approaches to producing message authentication?
Message encryption - The cipher text of the entire
image
serves as its authenticator.
Message
authentication code - (MAC) A public
function of the message and a
secret key that produces a fixed length value that serves as a authenticator.
Hash
function - A
public function that maps a message
of any length into a fixed– length hash value, which serves as
the
authenticator.
4) When combination
of symmetric encryption and an error control code is used for message authentication, in what order must
the two functions be performed?
The message is encrypted
first, and then the MAC is calculated using the resulting cipher text to form
the transmitted block.
5) What is a
message authentication code?
An
alternative authentication technique involves the use of a small fixed size
block of data, known as a cryptographic checksum or MAC that is appended to the
message.
6) What is the
difference between a message authentication code and a one-way hash function?
The
difference between an MAC and a one-way hash function is that unlike an MAC, a
hash code does not use a key but is a function only of the input message.
7) In what ways can
a hash value be secured so as to provide message authentication?
The ways in which a hash code can be used to provide
message authentication are:
The
message plus concatenated hash code is encrypted using symmetric encryption.The
hash code provides the structure required for authentication.
Only
the hash code is encrypted using symmetric encryption. This reduces the
processing burden.
Only
the hash code is encrypted using public key encryption and the sender’s private
key.This provides digital signature.
The
message plus the public key-encrypted hash code may be encrypted using a
symmetric secret key.
A
hash function may be used without encryption for message authentication.It
assumes that two communicating parties (A and B) share a common key (s).
’A’ computes the hash value over the
concatenation of M and S.B knows S and therefore can re-compute M.
The
entire message plus the hash code may be encrypted.
8) Is it necessary to recover the secret key in
order to attack a MAC algorithm?
A number of keys will produce the correct MAC and
the opponent has no way of knowing which is the correct key. On an awerage 2(n-k)
keys produce a match.Therefore attacks do not require the discovery of the key.
9)
What characteristics are needed in a secure hash function?
Requirements of a hash function(H):
H
can be applied to a block of data of any size.
H
produces a fixed length output.
H(x)
is easy to compute for any given x
For
any given value h it is computationally
infeasible to find y/x with H(y)=H(x).
It
is computationally infeasible to find any pair(x,y) such that H(x)=H(y).
10)
What is the difference between a strong and a weak collision resistance?
For
any given value h it is computationally
infeasible to find y/x with
H(y)=H(x).This is “weak collision resistance”.It is a one-way property.It is
easy to generate a code given a message, but almost impossible to do the
reverse.
It
is computationally infeasible to find any pair(x,y) such that H(x)=H(y).This is
“strong collision resistance”. This guarantees that an alternative message
hashing to the same value as a given message cannot be found.This prevents
forgery.
11)What
is the function of a compression
function in a hash function?
The hash function involves repeated use of a
compression function. The motivation is that if the compression function is
collision resistant, then the hash function is also collision resistant function.So a secure hash function
can be produced.
AUTHENTICATION APPLICATIONS
1.What problem was
Kerberos designed to address?
The problem that Kerberos addresses is this: Assume an open distributed
environment in which users at workstations wish to access
services on servers distributed throughout the network. We would like for
servers to be able to restrict access to authorized users and to be able to
authenticate requests for service. In this environment a workstation cannot be
trusted to identify its users correctly
to network services.
2.What are the
three threats associated with user authentication over a network or Internet?
The three threats are:
A
user may gain access to a particular workstation and pretend to another user
operating from that workstation.
A
user may alter the network address of a workstation so that the requests sent
from the altered workstation appear to come from the impersonated workstation.
A
user may eavesdrop on exchanges and use a replay attack to gain entrance to a
server or to disrupt operations.
3.List three
approaches to secure user authentication in a distributed environment?
Three approaches to secure user authentication in a distributed
environment are:
Rely
on each individual client workstation to assure the identity of its user or
users and rely on each server to enforce a security policy based on user
identification (ID).
Require
that client systems authenticate themselves to servers, but trust the client
system concerning the identity of its user.
Require
the user to prove identity for each service invoked. Also require that servers
prove their identity to clients.
4.What four requirements were defined for
Kerberos?
The four requirements defined for
Kerberos are:
Secure: A network eavesdropper should not be able to
obtain the necessary information to impersonate a user. More generally Kerberos
should be strong enough that a potential opponent does not find it to be the
weak link.
Reliable: For all services that relay on Kerberos for
access control, lack of availability of the supported services. Hence, Kerberos
should be highly reliable and should employ a distributed server architecture,
with one system able to back up another.
Transparent: Ideally, the user should not be aware that
authentication is taking place, beyond the requirement to enter a password.
Scalable: The system should be capable of supporting
large numbers of clients and servers. This suggests a modular, distributed
architecture.
5.What entities
constitute a full-service Kerberos environment?
A full service environment consists of a Kerberos server, a number of
clients and a number of application servers.
6.In the context of
Kerberos, what is a realm?
The
Kerberos server must have the user ID (UID) and hashed password of all
participating users in its database. All users are registered with the Kerberos
server.
The
Kerberos server must share a secret with each server. All servers are
registered with the Kerberos server.
Such an environment is referred to as realm.
7.What are the
principle differences between version 4 and version 5 of Kerberos?
The principle differences between version 4 and version 5 of Kerberos
are:
1.Encryption system dependence
2.Internet Protocol Dependence
3.Message byte ordering
4.Ticket Life Time
5.Authentication Forwarding
6.Interrealm Authentication
ELECTRONIC MAIL SECURITY
1. What are the five principle services provided by the PGP?
Function
|
Algorithm used
|
Description
|
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Digital Signature
|
DSS\SHA or
RSA\SHA
|
The hash code of
a message is created using SHA1.This message digest is encrypted using DSS or
RSA with the sender’s private key and included with the message
|
|
Message Encryption
|
CAST or IDEA or
Three-key Triple DES with Diffie-Hellman or RSA
|
A message is
encrypted using CAST-128 or IDEA or 3DES with a one-time session key
generated by the sender. The session key is encrypted using Diffie-Hellman or
RSA with the recipient’s public key and included with the message
|
|
Compression
|
ZIP
|
A message may be
compressed, for storage or transmission using ZIP
|
|
Email
compatibility
|
Radix 64
conversion
|
To provide
transparency for email applications, an encrypted message may be converted to
an ASCII string using radix 64 conversion
|
|
Segmentation
|
------
|
To accommodate
maximum message size limitations, PGP performs segmentation and reassembly
|
2.What is the
utility of a detached signature?
A detached signature may be stored
and transmitted separately from the message it signs. This is useful in several contexts. A user may wish to maintain a separate
signature log of all messages sent or received. A detached signature of an
executable program can detect subsequent virus infection. Finally detached signature can be used when
more than one party must sign a document, such as legal contract.
3. Why does PGP generate a signature before
applying compression?
The signature is generated
before compression due to 2 reasons:
1. It is preferable to sign an uncompressed message
so that one can store only the
uncompressed message together with the signature for future verification
2.
Even if one were willing to generate dynamically a recompressed message
for verification, PGP’s compression
algorithm presents a difficulty
4.What is Radix 64 conversion?
Radix 64 converts the input stream into radix 64 format.
It expands a message by 33%
5.Why is R 64
conversion useful for email generation?
The Radix 64 conversion is performed before the segmentation of the
messages take place
The use of radix 64 is that it converts he input stream to 33%. The radix
64 converts the input stream to a radix 64 format
6.What is MIME?
Multipurpose Internet Mail Extensions (MIME) is an extension to the RFC
822 framework that is intended to address some of the problems and limitations
of these use of SMTP.
Some of limitations: -
- It cannot
transmit executable files or folders.
- SMTP servers
may reject, mail message over a certain size.
7.Why is the segmentation and reassembly function in PGP is needed?
E-mail facilities often are restricted
to a maximum message length. To
accommodate this restriction, PGP automatically subdivides a message that is
too large into segments that are small enough to send via e-mail. The segmentation is done after all of the
other processing, including the radix-64 conversion. Thus, the session key component and signature
component appear only once, at the beginning of the first segment.
8.What is S/MIME?
Secure/Multipurpose
Internet Mail Extension is a security enhancement to the MIME Internet e-mail
format standard, based on technology from RSA Data Security. It is ability to sign and/or encrypt
messages.
9.What is RFC 822?
RFC 822 defines a
format for text messages that are sent using electronic mail.
It has been the standard for Internet-based text message and remains in
common use. In the RFC822 context,
messages are viewed as having an envelope and contents. The envelope contains whatever information
needed to accomplish transmission and delivery.
The contents compose the object to be delivered to the recipient.
10.How does PGP use
the concept of trust?
PGP provide a convenient means of using
trust, associating trust with public keys, and exploiting trust
information. Each entry in the
public-key ring is a public key certificate.
Associated with
each such entry is a key legitimacy field that indicates the extent to which
PGP will trust that this is a valid public key for this user; the higher the
level of trust, the stronger is the binding of this user ID to this key.
ipsec
1.Give examples of applications of IPSec?
Secure
branch office connectivity over the Internet.
Secure
remote access over the Internet.
Establishing
extranet and intranet connectivity with partners.
Enhancing
electronic commerce security.
2.What services are provided by IPSec?
Access
control
Connectionless
integrity
Data
origin authentication
Rejection
of replayed packets
3.What parameters identify an SA and What parameter Characterize the
nature of a particular SA?
A security association(SA) is uniquely identified by three parameters,
Security
Parameter Index(SPI)
IP
Destination Address
Security
Protocol Identifier
The parameters that characterize the particular SA
is
Sequence
number counter
Sequence
counter overflow
Anti-Replay
window
AH
Information
ESP
Information
Lifetime
of this SA
IPSec
Protocol Mode
Path
MTU
4.What is the difference between Transport mode and Tunnel mode?
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Transport mode
|
Tunnel mode
|
|
1.It provides
protection for upper layer protocols.
2.Used for
end-to-end communication between two host
3.AH:Authenticates
IP payload and selected portions of IP header and IPv6 extension header
|
1. It provides
protection to the entire IP packet.
3.It is used when
one or both ends of an SA is a
security gateway , such as firewall or router that implement IPSec.
3.Authenticates
entir inner IP packet plus selected portions of outer IP header and outer
IPv6 extension headers.
|
5.What is replay attack?
A replay attack is one which an attacker obtains a copy of an
authenticated packet and later transmit it to the intended destination.
6.Why does ESP include a padding field?
Padding
field is added to the ESP to provide partial traffic flow confidentiality by
concealing the actual length of the payload.
7.What are the basic approaches to bundling SAs?
1.Transport adjacency
Refers to
applying more than one security protocol to the same packet, without invoking
tunneling.
2.Iterated tunneling
Refers to
the application of multiple layers of security protocol affected through IP
tunneling.
FIREWALL
1.List the three
design goals for a firewall.
1.All traffic from inside to
outside, and vice versa, must pass through the firewall. This is achieved by
physically blocking all access to the local network except via the firewall.
2.Only authorized traffic,
as defined by the local security policy, will be allowed to pass. Various types
of firewalls are used, which implement various types of security policies.
3. The firewall itself is
immune to penetration. this implies that use of a trusted system with a secure
operating system.
2.List four
techniques used by firewalls to control access and enforce a security policy.
·
Service control
·
Direction control
·
User control
·
Behavior control
3.What information
does a typical packet-filtering router use?
Packet filtering router
uses the following information:
·
Source IP address:
The IP address of the system that originated the IP packet
·
Destination IP address:
The IP address of the system the IP packet is trying to reach
·
Source and destination transport-level address:
The
transport level port number,which defines
applications such as SNMP or
TELNET
·
IP protocol field:
Defines the transport protocol
·
Interface:
For a router with three or more
ports,which interface of the router the packet came from or which interface of
the router the packet is destined for.
4.what are some
weaknesses of a packet-filtering router?
·
They cannot prevents attacks that employ application-specific
functions.
·
Logging functionality is limited
·
Do not support advanced user authentication schemes.
·
It cannot detect a network packet in which the OSI
layer 3 addressing information has been alerted.
·
They are susceptible to security breaches caused by
improper configuration.
5.what is the difference between a packet-filtering router and a stateful
inspection firewall?
A simple
packet-filtering firewall must permit inbound network traffic on all these
high-numbered ports for TCP-based traffic to occur. This creates a
vulnerability that can be exploited by unauthorized users.
A stateful inspection packet filter
tightens up the rules for TCP traffic by creating a directory of outbound TCP
connection. The packet filters now allow incoming traffic to high-numbered
ports only for those packets that fit the profile of one of the entries in the
directory.
6. What is an
application level gateway?
An
application level gateway, are also called a proxy server, acts as a relay of
application level traffic. The user contacts the gateway using a TCP/IP
application, such as telnet or FTP, and the gateway asks the user for the name
of the remote host be accessed.
7. What is a
circuit level gateway?
A circuit-level gateway
does not permit an end-to-end TCP connection; rather, the gateway sets up two
TCP connections, one between itself and a TCP user on an inner host and other
between itself and a TCP user on an outer host. Once these connections are
established, the gateway typically relays TCP segments from one connection to
other without examining the contents.
8.what are the
differences among the three configuration of firewall?
In the screened host
firewall, single-homed bastion configuration, the firewall consists of two
systems: a packet-filtering router and a bastion host.
In
the screened host firewall, dual-homed bastion configuration prevents such a
security breach.
In the screened subnet firewall configuration is the most
secure one.
Here two packet filters are used, one between the bastion host and the
Internet and one between the bastion host and the internal network.
9.In the context access control, what is the difference between a subject
and an object?
Subject is an entity
capable of accessing objects. Any user or application actually gains access to
an object by means of a process that represents that user or application.
Object is one in which
anything is controlled.eg.files, programs and segments of memory.
10. What is the
difference between an access control list and a capability ticket?
An access control list
lists users and their permitted access rights for each object.
A capability ticket specifies authorized objects and operations
for a user. Each user has a no.of tickets and may be authorized to loan or give
them to others.
11.what are the two rules that a reference monitor enforces?
·
No read up
A subject can only read an object of less or equal
security level. This is referred to as simple security property.
·
No write down
A subject can only write into an object of grater or
equal security level. This is referred to as * property.
12.what properties
are required for a reference monitor?
·
Complete mediation: The security rules are enforced
on every access, just, for example, when a file is opened.
·
Isolation: The reference monitor and database are
protected from unauthorized modification.
·
Verifiability: The reference monitor’s correctness
must be provable
Web
Security
1.What are the
advantages of each of the three approaches shown in the figure?
Figure 1 : Figure 2:
HTTP
|
FTP
|
SMTP
|
TCP
|
IP/IPSec
|
|
HTTP
|
FTP
|
SMTP
|
SSL or TLS
|
TCP
|
|
IP
|
Figure 3:
|
|
S/MIME
|
PGP
|
SET
|
|
Kerberos
|
SMTP
|
HTTP
|
|
UDP
|
TCP
|
|
IP
|
Figure 1:
The advantage of using IPSec is
that it is transparent to end users and applications and provides a
general-purpose solution.Further,IPSec includes a filtering capability so that
only selected traffic need incur the overhead of IPSec processing.
Figure 2:
SSL(or TLS) could be provided as part
of the underlying protocol suite and
therefore be transparent to applications.
Figure 3:
The advantage of
this approach is that the service can be tailored to the specific needs of a
given application.
2. What protocols comprise SSL?
The protocols that comprise
SSL are:SSL Handshake Protocol,SSL Change Cipher Spec Protocol,SSL Alert
Protocol,Hypertext Transfer Protocol(HTTP) and SSL Recprd Protocol.
3. What is the difference between an SSL
connection and an SSL
session ?
A Connection is
a transport that provides a suitable type of service.For SSL,such connections
are peer-to-peer relationships.The connections are transient.
An SSL session
is an association between a client and a server.Sessions are created by the
Handshake Protocol.Sessions define a set of cryptographic security parameters,
which can be shared among multiple connections.
4. List and briefly
define the parameters that define an SSL session state.
A session state is defined by the following
parameters:
·
Session
identifier
·
Peer
certificate
·
Compression
method
·
Cipher
spec
·
Master
secret
·
Is
resumable
5. List and briefly define the parameters that
define an SSL session connection.
A connection state
is defined by the following parameters:
·
Server and client random
·
Server write MACsecret
·
Client write MACsecret
·
Server write key
·
Client write key
·
Initialization vectors
·
Sequence numbers
ESSAYS
1.Write notes on security service
1.AUTHENTICATION
The assurance that the
communicating entity is the one that it claims to be.
Peer Entity
Authentication:
Used in association with
a logical connection to provide confidence in the
identity of the entities
connected.
Data Origin
Authentication:
In a connectionless
transfer, provides assurance that the source of received
data is as claimed.
2.ACCESS CONTROL
The prevention of unauthorized use of a
resource (that is this service control who can have access to a resource, under
what condition access can occur, and what those accessing the resource are
allowed to do).
3.DATA
CONFIDENTIALITY
The protection of data from unauthorized
disclosure
Connection
Confidentiality:
The protection of all user data on a
connection.
Connectionless
Confidentiality:
The protection of all user data in a
single data block.
Selective –Field
Confidentiality:
The confidentiality
of selective field within the user data on a connection or in a single
data block.
Traffic-Flow
Confidentiality:
The protection of the information
that might be derived from observation of traffic flows.
DATA INTEGRITY
The assurance that data received are
exactly as sent by an authorized entity.
Connection Integrity with recovery:
Provides for the integrity of all
user data on a connection and detect any
modification,ionsertion,deletion,or replay
of any data within an entire data
sequence, with recovery attempted.
Connection
Integrity without recovery:
As above, but provides only
detection without recovery.
Selective-Field
Connection Integrity:
Provides for the integrity of
selected fields within the user data of the data block
transferred over a connection and
takes the form of determination of whether the
selected fields have been
modified,inserted,deleted or replayed.
Connectionless
Integrity:
Provides for the integrity of a
single connectionless data block and may take the
form of detection of data
modifivation.Additionally a limited form of replay
detection may be provided.
Selective-field
Connectionless Integrity:
Provides for the integrity of
selected fields within a single connectionless data
block: takes the form of
determination of whether the selected fields have been
modified.
5.NONREPUDIATION
Provides protection against denial by
one of the entities involved in a communication of having participated in all or part of the
communication.
Nonrepudiation
,Origin:
Proof that the message was sent by
the specified party.
Nonrepudiation,Destination:
Proof that the message was received
by the specified party.
2.Security Attacks
A
useful means of classifying security attacks, used both in x.800 and RFC 2828,
is in terms of passive attacks and active attacks. A passive attack attempts to
learn or make use of information from the system but does not affect system
resources. An active attack attempts to alter system resources or affect their
operation.
Passive attacks
Passive attacks are in the nature of eavesdropping on, or monitoring of,
transmissions. Two types of passive attacks are release of message contents and traffic
analysis. The release of
message contents is easily understood.
A telephone conversation, an electronic mail message, and a transferred file
may contain sensitive or confidential information.
A second type of passive
attack, traffic analysis, is subtler. Suppose that we had a
Way of masking the contents of messages or other information traffic so
that opponents, even if they captured the message, could not extract the
information from the message.
Passive attacks are very
difficult to detect because they do not involve any alteration of the data.
Active attacks
Active attacks involves some modification of the data stream or the
creation of a false
Stream and can be subdivided into four categories.
I.
Masquerade
II.
Replay
III.
Modification of message
IV.
Denial of service
A masquerade takes place when one entity when one entity
pretends to be a different entity. A masquerade attack usually includes one of
the other forms of active attack.
Replay involves the passive capture of a data unit and its subsequent
retransmission to produce an unauthorized effect.
Modification of messages simply means that some portion of a legitimate
message is altered or that messages are delayed or reordered, to produce an
unauthorized effect.
The denial of service prevents or
inhibits the normal use or management of communication facilities.
1.Explain about
transposition techniques?
All the substitution techniques involve the substitution of a cipher text
symbol for a plaintext symbol. A very different kind of mapping is achieved by
performing some sort of permutation on the plaintext letters. This technique is
referred to as a transposition cipher.
The simplest such cipher
is of the rail fence technique, in which the plaintext is written down as a
sequence of diagonals and then read off as a sequence of rows. For example, to
encipher the message “meet me after the toga party” with a rail fence of depth
2, we write the following:
m e
m a t
r h t
g p r y
e
t e f
e t e
o a a t
The encrypted message is
MEMATRHTGPRYETEFETEOAAT
This sort of thing would be trivial to cryptanalyze.
A more complex scheme is to write the message in a rectangle, row by row, and
read off the message off, column by column, but permute the order of the
columns. The order of the columns then becomes the key to the algorithm. For
example,
Key: 4
3 1 2 5
6 7
Plaintext: a
t t a
c k p
o s
t p o
n e
d u
n t i
l t
w o
a m x
y z
Cipher
text: TNNAAPTMTSUOAODWCOIXKNLYPETZ
A pure transposition cipher is easily recognized
because it has the same letter frequencies as the original plaintext. For the
type columnar transposition, cryptanalysis is fairly straightforward and
involves laying out the cipher text in a matrix and playing around with column
positions. Diagram and triagram frequency tables can be useful.
The transposition cipher can be made significantly
more secure by performing more than one stage of transposition. The result is a
more complex permutation that is not easily reconstructed. Thus, if the
foregoing message is re-encrypted using the same algorithm,
Key: 4
3 1 2 5 6 7
Plaintext: t
t n a a p
t
m
t s u
o a o
d w
c o i
x k
n l
y p e
t z
Cipher
text: NSCYAUOPTTWLTMDNAOIEPAXTTOKZ
To visualize the result of this double
transposition, designate the letters in the original plaintext message by the
numbers designating their position. Thus, with 28 letters in the message, the
original sequence of letters is
01
02 03
04 05 06 07 08
09 10 11
12 13 14
15 16 17
18 19
20 21 22
23 24 25
26 27 28
After the first
transposition we have
03 10
17 24 04 11 18
25 02 09
16 23 01
08
15 22 05
12 19 26
06 13 20
27 07 14
21 28
which has somewhat a regular structure. But after the second
transposition , we have
17
09 05 27
24 16 12
07 10 02
22 20 03
25
15 13
04 23 19 14 11
01 26 21
18 08 06
28
This is much less structured permutation and is much more difficult to
cryptanalyze.
2.Write short
notes on Steganography
The methods of
stegonagraphy conceal the existence of the message, whereas the methods of
cryptography render the message unintelligible to outsiders by various
transformations of the text. A simple form of steganography, but one that is
time consuming is one in which an arrangement of words or letters within an
apparently innocuous text spells out the real message.
Some of the other techniques are:
Ø
Character marking: Selected letters of printed or typewritten text are
overwritten in pencil. The marks are ordinarily not visible unless the paper is
held at an angle to bright light.
Ø
Invisible Ink:
A number of substances can be used for writing but leave no visible traces
until heat or some chemical is applied on the paper.
Ø
Pin punctures:
Small pin punctures on selected letters are ordinarily not visible unless the
paper is held up in front of a light.
Ø
Typewriter correction ribbon: Used between lines typed with a black
ribbon, the results of typing with the correction are visible only under a
strong light.
For example, The Kodak Photo CD format’s
maximum resolution is 2048 by 3072 pixels with each pixel containing 24 bits of
RGB color information. The least significant bit of each 24-bit pixel can be
changed without greatly affecting the quality of the image. The result is that
we can hide a 2.3-megabyte message in a single digital snapshot.
The advantage of steganography is
that it can be employed by parties who have something to lose should the fact
of their secret communication be discovered.
Steganography has a number of
drawbacks when compared to encryption. It requires a lot of overhead
information to hide relatively few bits of information.
1.Briefly describe
about the Strength of DES?
With a key length of 56 bits,
there are 256 possible Keys, Which is approximately 7.2* 1016
Keys. Thus, on the face of it, a brute-force attack appears impractical.
Assuming that, on average half the key space has to be searched, a single
machine performing one DES encryption per microsecond would take more than a
thousand years to break the cipher
However, the assumption of
one encryption per microsecond is overly conservative. As far back as1977,
Diffie and hellman postulated that the technology existed to built a parallel
machine with 1 million encryption devices, each of which could perform one
encryption per microsecond. This would bring the average search time down to
about 10 hours. The authors estimated that the cost would be about $20 million in 1977
dollars.
DES finally and
definitively proved insure in July 1988, when the electronic Frontier
Foundation (EFF) announced that it had broken a DEF encryption using a special-purpose “DES cracker”
machine that was built for less than $250,000. The attack took less than three
days. The EFF has published a detailed description of the machine, enabling
others to build their own cracker. And, of course, hard ware
prices will
continue to drop as speeds increase, making DES virtually Worthless.
It is important to note that there
is more to a key-search attack than simply running through all possible keys.
Unless known plaintext is provided the analyst must be able to recognize
plaintext as plaintext .If the message
is just plaintext in English,
then the result
pops out easily, although the task of recognizing English would have to be
automated. If the text message has been compressed before encryption, then
recognition is more difficult. And if the message is some more general type of
data, such as numerical file, and this has been compressed, the problem becomes
more difficult to automate, the supplement the Brute-force approach, some degree of knowledge about the
expected plaintext is needed, and the handsome means of automatically
distinguishing plaintext from garble is also needed. The EEF approach addresses
this issue as well and introduces some automated techniques that would be
effective in many context.
The Nature of DES Algorithm
Another concern is the possibility that the
cryptanalysis is possible by exploiting the characteristics of the DES
algorithm. The focus of concern has been on the eight substitution tables, or
S-boxes that are used in each iteration. Because the design criteria for these
boxes, and indeed for the entire algorithm, were not made public, there is a
suspicion that the boxes were constructed in such a way that cryptanalysis is possible for an opponent who
knows the weaknesses in the S-boxes. This assertion is tantalizing, and over
the years a number of regularities and unexpected behaviors of the s-boxes have
been discovered. Despite this no one has so far succeeded in discovering the
supposed fatal weaknesses in the s-boxes.
Timing Attacks
A timing attack is one in which
information about the key or plaintext is obtained by observing how long it
takes a given implementation to perform decryptions on various cipher texts. A
timing attack exploits the facts that the encryption and decryption algorithm
often takes slightly different amounts of time on different inputs. report on
an approach that yields the Hamming weight of the secret key. This is the long
way from knowing the actual key, but it is an intriguing first step. DES
appears to be fairly resistant to a successful timing attack but suggest some
avenues to explore.
2.Briefly
explain about DES design criteria?
The
criteria used in the design of DES, focused on the design of the S-boxes and on the P function that takes the output
of the S boxes .The criteria for the S-boxes are as follows:
- No output bit of any S-box should be
too close a linear function of the input bits. Specifically,if we select
any output bit and any subset of
the six input bits, the fraction of inputs for which this output bit
equals the XOR of these input bits should not be close to 0 or 1, but
rather should be near ½.
- Each row of an S-box should include all
16 possible output bit combinations.
- if two inputs to an S-box differ in
exactly one bit, the outputs must differ I atleast two bits.
4.If two inputs to
an S-box differ in their first two bits and are identical in their last two
bits, the two outputs must not be the same.
5.For any non zero
6-bit difference between inputs, no more than8 of the 32 pairs of inputs
exhibiting that difference may result in the same output difference.
6.This is a criterion
similar to the previous one, but for the case of three S boxes.
Coppersmith pointed
out that the first criterion in the preceding list was needed because the
S-boxes are the only nonlinear part of DES. If the S-boxes were linear ,the
entire algorithm would be linear and easily broken. We have seen this
phenomenon with the Hill Cipher, which is linear. The remaining criteria were
primarily aimed at thwarting differencial cryptanalysis and at providing good
confusion properties.
The criteria for
the permutation P are as follows:
- The four output bits from each S-box at
round I are distributed so that two of them affect “middle bits” of
round(I+1) and the other two affect end bits. The end bits are the two
left-hand bits and the two righthand bits, which are shared with adjacent
S-boxes.
- The four output bits from each S-box
affect six different S-boxes on the next round, and no two affect the same
S-box.
- For two S-boxes j,k, if an output bit
from Sj, affects a middle bit of Sk on the next round,then an output bit
from Sk cannot affect a middle bit of Sj. This implies that for j=k, an
output bit from Sj must not affect a middle bit of Sj.
These
criteria are intended to increase the diffusion of the algorithm.
Key management
There
are two aspects to the use of public-key cryptography
in this regard:
The
distribution of public keys
The use
of public-key encryption to distribution secret
keys.
Distribution
of public keys
Four
general categories of schemes for the distribution of public keys.
Public
announcement
Publicly
available directory
Public-key
authority
Public-key
certificates
Public announcement of public keys
KUa KUb
. .
. . .
. .
KUb
KUa
Here the public-key is public
one. For example PGP.
Although
this approach is convenient, it has a weakness that anyone can forge such a
public announcement.
Publicly available directory
It has the following elements:
The
authority maintains a directory with a entry for each participant.
Each
participant registers a public key with the directory authority.
A
participant may replace the existing key with a new one at any time.
Periodically,
the authority publishes the entire directory or updates to the directory.
Participants
could also access the directory
electronically.
KUa
KUb
Public-key authority
(1) Request||timer1 (5) EKRauth
[kua||Request||Time2]
(2) EKRauth [Kub||Request ||Time1]
(4)Request||Time2]
(3) EKUa [Ida||N1]
(6)EKUa[N1||N2]
(7) EKUb [N2]
It
has the following steps:
Time
stamp message
Authority
public key
A sends
id of A and a nonce it B
B
receives A’s public key
B sends
a message to A
A
returns N2 encrypted using B’s public key
Public-key certificates
Certificate that can be used by
participants to exchange keys without contacting a public-key authority.
KUa KUb
CB=EKRauth
CA=EKRauth [Time1,IDA,KUa] [Time2,IDB,Kub]
Public key distribution of secret keys
Simple secret key
distribution
(1) KUa||IDA
(2)
EKUa [Ks]
1.A
generate KUa, KRa and sends Kua and IDA
2.B
generate ks and encrypts it using EKUa
3.A
discards KUa and KRa
4.B
discards KUa
5.Transaction
using conventional methods
Secret key distribution with confidentiality and authentication
(3)EKUb[N2]
(4)EKUb
[EKRa[ks]]
2.Diffie-Helman key exchange
Solution
to problem of key agreement or key exchange in 1976
Two
parties can agree on a symmetric key
Key can
be used for encryption or decryption
Once
parties agree on the key symmetric key encryption algorithm is used for
confidential
Algorithm
Alice
and Bob agree on two larges prime no.s n and g
Alice chooses large random no x and calculate
A=gx mod n
Alice
send the no A to Bob
Bob
independently chooses another large random integer y and calculate
B=gy mod n
Bob
sends B to Alice
Now A
computes the secret key k1
k1=Bx mod n
B
computes the secret key k2
k2=Ax mod n
k1=k2=k
symmetric key
1.Explain Message Authentication Code
This technique assumes that two communicating
parties A and B share a common key K.When A sends a message to B it calculates the MAC as a
function of the message and the key:MAC=CK{M),
Where,
M=input
message
C=MAC
function
K=shared
secret key
MAC=message
authentication code
The
message plus the MAC are transmitted to the recipient. The recipient performs
the same calculation on the received message to generate a new MAC.The received
MAC is compared to the calculated MAC.If only the sender and receiver know the
secret key,if the received MAC matches the calculated MAC , then
1.The
receiver is assured that the message has not been altered.
2.The
receiver is assured that the message is from the alleged sender.
3.If
the message includes a sequence number then the receiver is assured of the
proper sequence.
The MAC function need not be
reversible.Usually, it is a many-to-one function.
If
there are N possible messages then an n bit
MAC is used where N>>2n and there are 2k possible keys
where the key has k bits.
For example, if we are using 100 bit messages then there
are 2100 different messages and if a 10 bit MAC is
used there are 210 different MACs. On an average each MAC value is
generated by a total of (2100/210)=290 different
messages. If a 5bit key is used there are 25=32
different mappings from a set of messages to a set of MAC values.
Usually
two separate keys are used each of which is shared by the sender and
receiver.The message is calculated with the message as input and is then
concatenated to the message.The entire block is then encrypted.
The fig shows the
basic uses of MAC.
MAC is used when:
1.There are a
number of applications in which the same message is broadcast to many
destinations.
2.When there
exchanges where there is heavy load on one side and there is no time to
decrypt.
3.For
authentication of a computer in plain text.
4.When it is not needed to keep messages
secret but it is important to provide authentication.
5.Because
separation of authentication and confidentiality provides architectural
flexibility.
6.When users wish
to prolong the period of protection beyond the time of reception and yet allow
processing of message contents.
MAC does not
provide digital signature because both sender and receiver share the same key.
REQUIREMENTS OF MAC:
Assume that the
opponent knows the MAC function C but does not know the key K.Then the MAC
function should have the following properties:
1.If an opponent
observes M and CK(M), it should be computationally infeasible for
the opponent to construct a message M' such that CK(M')=CK(M).
2.CK(M) should be
uniformly distributed in the sense that for randomly chosen messages M and M',
the probability that CK(M)=CK(M') IS 2-n, where
n is the number of bits in the MAC.
3.Let M' be equal
to some known transformation on M.That is, M'=f(M).For example, f may involve
inverting one or more specific bits.In that case,Pr[CK(M)=CK(M')]=2-n.
2.Hash Function
A variation on the
message authentication code is the one-way hash function. As with the message
authentication code, a hash function accepts a variable size message M as input
and produces a fixed-size output , referred to as hash code H(M).
A variety of ways in which hash code
can be used to provide message authentication, as follows:
The
message plus concatenated hash code is encrypted using symmetric encryption.
Only
the hash code is encrypted using symmetric encryption.
Only
the hash code is encrypted using the public-key encryption and using the
sender’s private key.
If
confidentiality as well as a digital
signature is desired ,then the message plus the public key encrypted hash code
can be encrypted using a symmetric secret key.
This
technique uses a hash function but no encryption for message authentication.
Confidentiality
can be added to the approach of(e) by encrypting the entire message plus the
hash code.
|
|
A ----Ã B: M || Ck(M)
·
Provides
authentication
---- Only A and B share K
(a)Message
authentication
----------------------------------------------------------------
A ----Ã B: Ek2[M || Ck1(M)
·
Provides
authentication
----- Only A and B share K1
·
Provides
confidentiality
Only A and B share K2
(b)Message authentication and
confidentiality:
authentication tied to
plain text
-----------------------------------------------------------------------------
A -----Ã B:EX2[M] CK1(CK2[M2])
·
Provides
authentication
------- Using K1
·
Provides
confidentiality
-------Using K2
(c)Message authentication and
confidentiality
authentication tied to
cipher text.
|
|
When
confidentiality is not required , methods (b) and (c) have an advantage over
those that encrypt the message in that less computation is required
1.Write about the
AH and ESP associated with IPSec
AUTHENTICATION
HEADER
The authentication header provides support
for data integrity and authentication of IP packets. The data integrity feature
ensures that undetected modification to a packet’s content in transit is not
possible. The authentication feature enables an end system or network to
authenticate the the user or application
and filter traffic accordingly.
Authentication is
based on the use of a message authentication code(MAC)
The authentication header consists
of the following fields.
- Next header(8 bits):Identifies the type
of header immediately following this header.
- Payload length(8 bits):Length of
authentication header in 32-bit words,minus 2.
- Reserved(16 bits):For future use.
- Security parameters index(32
bits):Identifies a security association.
- Sequence number(32 bits):A
monotonically increasing counter value.
- Authentication data(variable):A
variable-length field that contains the Integrity Check Value.
Anti-replay
service
A replay attack is one in which an
attacker obtains a copy of an authenticated packet and later transmits it to
the intended destination. The sequence number field is designed to thwart such
attacks.
Integrity check
value
The authentication data field holds
a value referred to as the integrity check value. The ICV is a message
authentication code or a truncated version of a code produced by a MAC
algorithm.
Transport and
tunnel modes
These are the two ways in which the
IPSec authentication service can be used.In one case authentication is provided
directly between a server and client work stations;the work station can be
either on the same network as the server or on an external network.As long as
the work station and the server share a protected secret key, the
authentication process is secure.This case uses a transport mode SA. In the
other case a remote work station authenticates itself to the corporate
firewall, either for access to the entire internal network or because the
requested server does not support the authentication feature. This case uses a
tunnel mode SA.
For transport mode AH using IPv4,
the AH is inserted after the original IP header and before the IP payload.
In the context of IPv6, the AH is
viewed as an end-to-end payload;that is it is not examined or processed by
intermediate routers. Therefore the AH
appears after the IPv6 base header and the hop-by-hop,routing and fragment
extension headers.
For tunnel mode AH the original IP
packet is authenticated, and the AH is inserted between the original IP header
and a new outer IP header
IPv4
|
Orig IP hdr
|
Extension hdrs if present
|
TCP
|
Data
|
IPv6
IPv4
IPv6
|
Orig IP hdr
|
hop-by-hop , dest,routing,fragment
|
AH
|
dest
|
TCP
|
data
|
|
New IP hdr
|
AH
|
Orig IP hdr
|
TCP
|
Data
|
IPv4
IPv6
|
New IP hdr
|
Ext hdrs
|
AH
|
Orig IP hdr
|
Ext hdrs
|
TCP
|
data
|
ENCAPSULATING
SECURITY PAYLOAD
The encapsulating security payload
provides confidentiality services , including confidentiality of message
contents and limited traffic flow confidentiality.As an optional feature , ESP
can also provide the same authentication services as AH.
ESP Format
ESP packet contains
the following fields
- Security parameters index(32
bits):Identifies a security association.
- Sequence number(32 bits):A
monotonically increasing counter value;this provides an anti-replay function,as
discussed for AH.
- Payload data(variable):This is a
transport level segment(transport mode)or IP packet(tunnel mode)that is
protected by encryption.
- Padding(0-255 bytes):The padding field
serves several purposes:
- If an encryption algorithm requires
the plain text to be a multiple of some number of bytes the padding field is used to expand the
plain text to the required length.
- The ESP format requires that the
cipher text must be an integer multiple of 32 bits. The padding field is
used to assure this alignment.
- Additional padding may be added to
provide partial traffic flow confidentiality by concealing the actual
length of the payload.
- Pad length(8 bits):Indicates the nuber
of pad bytes immediately preceding this field.
- Next header(8 bits):Identifies the type
of data contained in the payload data field.
- Authentication data(variable):A
variable length field that contains the Integrity Check Value computed
over the ESP packet minus the authentication data field.
Transport and
tunnel modes
Figure shows the two ways in which
IPsec ESP services can be used.Hosts on the internal networks use the internet
for the transport of data but do not interact with the other internet based
hosts. By terminating the tunnels at the security gateway to each internal
network the configuration allows the hosts to avoid implementing the security
capability . The former technique is supported by a transport mode SA, while
the latter technique uses a tunnel mode SA.
Transport mode ESP
Transport mode ESP is used to
encrypt and optionally authenticate the data carried by IP. For this mode using
IPv4, the ESP header is inserted into the IP packet immediately prior to the
transport layer header and an ESP trailer is placed after the IP packet.
In the context of IPv6, ESP is
viewed as an end-to-end payload ; that is it is not examined or processed by
intermediate routers. Therefore the ESP header appears after the IPv6 base
header and the hop-by-hop, routing and
fragment extension headers.The destination option extension could appear before
or after the ESP header, depending on the semantics required.For IPv6
encryption covers the entire transport level segment plus the ESP trailer plus
the destination options extension header if it occurs after the ESP header.
IPv4
|
Orig IP hdr
|
ESP hdr
|
TCP
|
data
|
ESP trlr
|
ESP auth
|
IPv6
|
orig IP hdr
|
hop-by-hop ,
dest,routing,fragment
|
ESP hdr
|
dest
|
TCP
|
data
|
ESP trlr
|
ESP auth
|
Tunnel mode ESP
Tunnel mode ESP is used to encrypt the entire IP packet . For this
mode the ESP header is prefixed to the packet and then the packet plus the ESP
trailer is encrypted. This method can be used to counter the traffic analysis.
IPv4
|
New IP hdr
|
ESP hdr
|
Orig IP hdr
|
TCP
|
data
|
ESP trlr
|
ESP auth
|
IPv6
|
new IP hdr
|
Ext hdrs
|
ESP hdr
|
Orig IP hdr
|
Ext hdrs
|
TCP
|
data
|
ESP trlr
|
ESP auth
|
2.Write about how security associations can be combined.
An individual SA can implement
either the AH or ESP protocol but not
both. Sometimes a particular traffic flow will call for the services provided
by both AH and ESP.Multiple SA must be employed for the same traffic flow to
achieve the desired IP services. The term security association bundle refers to
a sequence of SAs through which traffic must be
processed to provide a desired set of IPsec services. The SAs in a
bundle may terminate at different endpoints or at the same endpoints.
Security associations may be
combined into bundle in two types.
- Transport adjacency: Refers to applying
more than one security protocol to
the same IP packet without invoking tunneling.
- Iterated tunneling: Refers to the
application of multiple layers of security protocols effected through IP
tunneling.
The two approaches can be combined for example
by having a transport SA between hosts travel part of the way through a tunnel
SA between security gateways
Authentication plus
confidentiality
Encryption and authentication can be combined inorder to
transmit an IP packet that has both
confidentiality and authentication between hosts.
ESp with authentication option
In this approach the
user first applies ESP to the data to be protected and the appends the
authentication data field. There are two sub cases.
Transport mode ESP:Authentication
and encryption apply to the IP payload delivered to the host but the IP header
is not protected.
Tunnel mode ESP:Authentication
applies to the entire IP packet delivered
to the outer IP destination address and authentication is performed at
that destination.
For both the cases
authentication applies to cipher text rather than the plain text.
Transport adjacency
Another way to apply
authentication after the encryption is to use two bundle transport SAs with the
inner being an ESP SA and the outer being an AH SA . In this case ESP is used
without its authentication option. Because the inner SA is a transport SA,
encryption is applied to the IP payload. The resulting packet consists of an IP
header followe by an ESP. AH is then
applied in the transport mode so that authenticayion covers the ESP plus the
original IP header except for mutable
fields.
Transport-Tunnel bundle
One approach to applying authentication before encryption
between two hosts is to use a bundle consisting of an inner AH transport SA an
outer ESP tunnel SA. IN this case authentication is applied to the IP payload
plus the IP header except for the mutable fields. The resulting IP packet is
then processed in the tunnel mode by the ESP; the result is that the entire
authenticated inner packet is encrypted and a new outer IP header is added.
Basic combinations
of security associations
In case1 all security is provided
between end systems that implement
IPsec. For any two end systems to communicate via an SA they must share
the appropriate secret keys. The following
are among the possible combinations.
- AH in transport mode.
- ESp in transport mode.
- AH followed by ESP in transport mode.
- Any one of a,b, or c inside an AH or
ESP in tunnel mode.
For case2 security
is provided only between gateways and no hosts implement IPsec.
Case3 builds on
case2 by adding end-to-end security. The gateway –to-gateway tunnel provides
either authentication or confidentiality or both for all traffic between end
systems. When the gateway-to-gateway tunnel is ESP it also provides a limited
form of traffic confidentiality.
Case4 provides
support for a remote host that uses the internet to reach an organization’s
firewall and then to gain access to some server or workstation behind the
firewall. Only tunnel mode is required between the remote host and the firewall
.
7
1.Explain S/MIME?
S/MIME
Secure/Multipurpose
Internet Mail Extension is a security enhancement to the MIME Internet e-mail
format standard, based on technology from RSA Data Security. It is ability to sign and/or encrypt messages.
RFC
822
RFC 822 defines a
format for text messages that are sent using electronic mail.
It has been the standard for Internet-based text message and remains in
common use. In the RFC822 context,
messages are viewed as having an envelope and contents. The envelope contains whatever information
needed to accomplish transmission and delivery.
The contents compose the object to be delivered to the recipient.
MIME
Multipurpose Internet Mail Extensions (MIME) is an extension to the RFC
822 framework that is intended to address some of the problems and limitations
of the use of SMTP.
Some of limitations: -
1.It cannot transmit
executable files or folders.
2.SMTP servers may reject,
mail message over a certain size.
- Some SMTP
implementations do not adhere completely to the SMTP standards defined in
RFC 821. Common problems include
Deletion,
addition, or reordering of carriage return and linefeed
Truncating
or wrapping lines longer than 76 characters
Removal
of trailing white space
Padding
of lines in a message to the same length
Conversion
of tab characters into multiple space characters
The MIME specification includes the following elements:
1.Five message header fields are defined which may be included in and RFC
822 header.
2.A numbers of content formats are defined, thus standardizing
representations that support multimedia electronic mail.
3.Transfer encodings are defined that enable the conversion of any
content format into a form that is protected from alteration by the mail
system.
S/MIME
Functionality
It offers
ability to sign and/or encrypt messages.
Functions
Enveloped
Data: This consists of encrypted content of any type and encrypted content
encryption keys for one or more recipients.
Signed
Data: A digital signature is formed by taking the message digest of the content
to be signed and then encrypting that with the private key of signer. The
content plus signature are the encoded using base64 encoding.
Clear-signed
data: As with assigned data, a digital signature of the content is formed. In
this case only the digital signature is encoded using base64.
Signed
and enveloped date: Signed-only and encrypted-only entities may be nested, so
that encrypted data may be signed and signed data or clear-signed data may be
signed and signed data or clear-signed data may be encrypted.
Cryptographic algorithms
|
Function
|
Requirement
|
|
Create a message digest to be used in
Forming a digital signature
Encrypt session key for transmission
with message
|
MUST support SHA-1.
Receiver SHOULD support md5 for backward compatibility
Sending and receiving agents MUST support Diffie-Hellman.
Sending agents Should support RSA encryption with key sizes 51 bits to
1024 bits.
|
MUST: The definition is an absolute requirement of
the specification. An implementation
must include this feature or function to be in conformance with the
specification.
SHOULD: There may exist valid reasons in particular
circumstances to ignore this feature or function, but it is recommended that an
implementation include this feature of function.
S/MIME incorporates
three public-key algorithms. The Digital
Signature Standard (DSS) is the preferred algorithm for digital signature. S/MIME use a variant of Diffie-Hellman that
does provide encryption/decryption.
The S/MIME
specification includes a discussion of the procedure for deciding which content
encryption algorithm to use.
A sending agent should follow the following rules, in the following
order:
- The sending
agent SHOULD choose the first capability on the list that it is capable of
using.
- If the
sending agent has no such list of capabilities from an intended recipient
but has received one or more messages from the recipient, then the
outgoing message SHOULD use the same encryption algorithm as was used on
the last signed and encrypted message received from that intended
recipient.
- If the
sending agent has no acknowledge about the decryption capabilities of the
intended recipient and is willing to risk that the recipient may not be
able to decrypt the message, then the sending agent SHOULD use tripleDES.
- 4. If the
sending agent has no knowledge about the decryption capabilities of the
intended recipient and is not willing to risk that the recipient may not
be able to decrypt the message, then the sending agent MUST use RC2/40.
Securing a MIME Entity
S/MIME secures a MIME entity with a signature,
encryption, or both. A MIME entity may
be an entire message, or if the MIME content type is multipart, then a
MIME entity is one or more of the
subparts of the message. Then the MIME
entity plus some security related date, such as algorithm identifies and
certificated, are processed by S/MIME to produce what is known as a PKCS
object. A PKCS object is then treated as
message content and wrapped in MIME.
S/MIME
Certificate Processing
S/MIME uses public-key
certificates. The key-management scheme
used by S/MIME is in some ways a hybrid between a strict X.509 certification
hierarchy and PGP’s web of trust. As
with the PGP model, S/MIME managers and/or users must configure each client
with a list of trusted keys and with certificate revocation lists. That is the responsibility is local for
maintaining the certificated needed to verify incoming signatures ad to encrypt
outgoing messages. On the other hand,
the certificates are signed by certification authorities.
An S/MIME user has several key management functions to perform:
- 1.Key
generation: Each key pair MUST be generated from a good source of
nondeterministic random input and be protected in a secure fashion.
- 2.Registration:
A user’s public key must be registered with a certification authority in
order to receive an X.509 public key certificate.
- 3.Certificate
storage and retrieval: A user requires access to local list of
certificated in order to verify incoming signatures and to encrypt
outgoing messages.
2. PRETTY GOOD
PRIVACY
PGP provides a
confidentiality and authentication service that can be used for electronic mail
and file storage applications. Phil Zimmermann has done the following:
1. Selected the best available cryptographic as building blocks
2. Integrated these algorithms into a general purpose application that is
independent of operating system and processor and that is based on a small set
of easy to use commands
3. Made the package and its documentation including the source code,
freely available via internet ,bulletin boards ,and commercial networks such as
AOL
4. Entered into an agreement with a company to provide a fully
compatible, low cost commercial version of PGP.
PGP has grown explosively and now widely used. A number of reasons can be
cited for this growth,
1. It is available free worldwide in versions that run on a variety of
platforms,including windows ,UNIX,Macintosh,and many more.
2. It is based on algorithms that have survived extensive public review
and are considered extremely secure.
3. It has a wide range of applicability from corporations that wish to
select and enforce a standardized scheme for encrypting files and messages to
individuals who wish to communicate securely with others worldwide over the
internet and other networks .
4. It was not developed by ,nor is it controlled by, any governmental or
standard organization
5. PGP is now on an internet standards track.
Notation
Ks =Session key used in symmetric encryption scheme
KRa=Private key of user A used in public key encryption
scheme.
KUa= Public key of user A, used in public key encryption
scheme
EP = Public key encryption
DP = Public key decryption
EC = Symmetric encryption
DC = Symmetric decryption
H = Hash function
|| = Concatenation
Z = compression using ZIP algorithm
R64 = Conversion to radix 64 ASCII format R64 = Conversion to radix 64
ASCII format DP
DP
Operational
Description
PGP provides five services
Authentication
– DSS/SHA or RSA/SHA
Confidentiality
– CAST or IDEA or 3DES Diffe or RSA
Compression
–ZIP
Email
Compatibility – Radix 64 conversion
Segmentation
Authentication
1. The sender creates a message
2. SHA-1 is used to generate a 160 bit hash code
of the message
3. The hash code is encrypted with RSA using the sender’s private key,and
the result is prepended to the message
4. The receiver uses RSA with the sender’s public key to decrypt and
recover the hash code
5. The receiver generates a new hash code for the message and compares it
with the decrypted hash code
Confidentiality
1. The sender generates a
message and random 128 bit number to be used as a session key for this message
only
2. The message is encrypted ,using CAST -128 with the session key
3. The session key is encrypted with RSA with its private key to decrypt
and recover the session key
4. The session key is used to decrypt the message
5.The receiver uses RSA with its private key to decrypt and recover the
session key
Compression
1. The signature is generated before compression for 2 reasons
a. It is preferable to sign an
uncompreesed message so that one can store only the compressed message together
with the signature for future verification
b. Even if one were willing to
generate dynamically a recompressed message for verification
2.The message encryption is applied after compression to strengthen
cryptographic security
Email Compatibility
When PGP is used , atleast part
of the block to be transmitted is encrypted.If only the signature service is
used then the message digest is encrypted.If the confidentiality service is
used , the message plus signature are encrypted .Thus part or all of the
resulting block consist of a stream of arbitrary 8 bit octets.
Segmentation and reassembly
Email facilities often are
restricted to a maximum message length.To accommodate this restriction PGP
automatically subdivides the message that is too large into segments that are
small enough to send via email
Cryptographic Keys and Key rings
1. A means of generating unpredictable session keys is needed
2. We would like to allow a user to have multiple public-key/private-key
pairs
The user may wish to change his or
her key pair from time to time.Also the recipient will know only the old
private key until an update reaches them
3. Each PGP entity must maintain a file of its own public/private key
pairs as well as a file of public keys of correspondence
Key Rings
Private Key Rings
Timestamp:
The date/time when this key pair was generated
Key
ID: The least significant 64 bits of the public key for the entry
Public
key: The public key portion of the pair
Private
key: The private key portion of the pair
User
ID: is the user’s email address
Public key Rings
Timestamp:The
date/time when the entry was generated
Key
ID: The least significant 64 bits of the public key for this entry
Public
key: the public keys for this entry
UserID:
Identifies the owner of this key
PGP
MESSAGE GENERATION
||
1.Differences between version4 and version5
Version4 had the following
environmental shortcomings:
1.Ecryption system
dependence:
It requires the use of DES
2.Internet protocol
dependence:
requires the use of internet protocol addresses
3.Message byte
ordering:
Sender of a message employs a byte ordering of its own choice
4.Ticket lifetime
Lifetime values are encrypted in an 8 bit quantity.
5.Authentication
forwarding:
It does not allow credentials issued to one client to be forwarded to
some other host and used by some other client.
6.Interrealm
authentication:
Interoperability among N realms requires the order of N2
kerberos to kerberos relationships.
Apart from these it had the following technical deficiencies:
1.Double encryption
The tickets provided to clients are encrypted twice.
2.PCBC encryption
Encryption makes use of a nonstandard mode of DES known as Propagating
Block Chaining(PCBC)
3.Session keys
each ticket includes a session key that is used by the client.
4.Password attacks
Both versions are vulnerable to a password attack.
These are overcome in version 5.
1.Differences between version4 and version5
Version4 had the
following environmental shortcomings:
1.Ecryption system dependence:
It requires the use
of DES
2.Internet protocol dependence:
requires the use of
internet protocol addresses
3.Message byte ordering:
Sender of a message
employs a byte ordering of its own choice
4.Ticket lifetime
Lifetime values are
encrypted in an 8 bit quantity.
5.Authentication forwarding:
It does not allow
credentials issued to one client to be forwarded to some other host and used by
some other client.
6.Interrealm authentication:
Interoperability
among N realms requires the order of N2 kerberos to kerberos
relationships.
Apart from these it
had the following technical deficiencies:
1.Double encryption
The tickets
provided to clients are encrypted twice.
2.PCBC encryption
Encryption makes
use of a nonstandard mode of DES known as Propagating Block Chaining(PCBC)
3.Session keys
each ticket
includes a session key that is used by the client.
4.Password attacks
Both versions are
vulnerable to a password attack.
These are overcome
in version 5.
2.Version5 authentication dialogue
It consists of
1.user ID and TGS
2.Realm
Indicates realm of a user
5.Nonce
A random value
that is repeated in the message to assure that the response is fresh.
The client server
authentication exchange includes the features:
Subkey:Client’s choice of an encryption key for an
application’s session.
Sequence number:An optional field that specifies the starting
sequence number to beused by the server for messages to the client.
TICKET FLAGS that
are used include:
INITIAL
This ticket was
issued by the AS protocol and not based on the ticket granting ticket.
PRE-AUTHENT
During initial
authentication the client was authenticated by the KDC.
HW-AUTHENT
The protocol employed for initial authentication required the use of
hardware.
RENEWABLE
MAY-POSTDATE
Tells TGS that a
postdated ticket may be issued based on this ticket granting ticket.
POSTDATED
INVALID
This ticket is
invalid and must be validated by the KDC.
PROXIABLE
Tells TGS that a
new service granting ticket with a new network address may be issued. based on
this presented ticket.
PROXY
Indicates that
this ticket is a proxy.
FORWARDABLE
Tells TGS that a new ticket granting ticket with a new network address
may be issued. based on this ticket granting ticket
FORWARDED
Indicates that
this ticket has either been forwarded or was issued based on authentication
involving a forwarded ticket granting ticket.
Ans:-- INTRODUCTION:
The term ‘cyber crime’ is a misnomer. This term has
nowhere been defined in any statute /Act passed or enacted by the Indian
Parliament. The concept of cyber crime is not radically different from the
concept of conventional crime. Both include conduct whether act or omission,
which cause breach of rules of law and counterbalanced by the sanction of the
state.
Before
evaluating the concept of cyber crime it is obvious that the concept of
conventional crime be discussed and the points of similarity and deviance
between both these forms may be discussed.
CONVENTIONAL
CRIME-
Crime is a social and economic phenomenon and is
as old as the human society. Crime is a legal concept and has the sanction of
the law. Crime or an offence is “a
legal wrong that can be followed by criminal proceedings which may result into
punishment.”(1)
The hallmark of criminality is that, it is breach of the criminal law. Per Lord
Atkin “the criminal quality of an act
cannot be discovered by reference to any standard but one: is the act
prohibited with penal consequences”.
(2)
A
crime may be said to be any conduct accompanied by act or omission prohibited
by law and consequential breach of which is visited by penal consequences.
CYBER
CRIME
Cyber
crime is the latest and perhaps the most complicated problem in the cyber
world. “Cyber crime may be said to be those species, of which, genus is the
conventional crime, and where either the computer is an object or subject of
the conduct constituting crime” (13).
“Any criminal activity that uses a
computer either as an instrumentality, target or a means for perpetuating
further crimes comes within the ambit of cyber crime”(12)
A
generalized definition of cyber crime may be “ unlawful acts wherein the computer is either a tool or target or both”(3) The computer may be
used as a tool in the following kinds of activity- financial crimes, sale of
illegal articles, pornography, online gambling, intellectual property crime,
e-mail spoofing, forgery, cyber defamation, cyber stalking. The computer may
however be target for unlawful acts in the following cases- unauthorized access
to computer/ computer system/ computer networks, theft of information contained
in the electronic form, e-mail bombing, data didling, salami attacks, logic
bombs, Trojan attacks, internet time thefts, web jacking, theft of computer
system, physically damaging the computer system.
DISTINCTION
BETWEEN CONVENTIONAL AND CYBER CRIME-
There
is apparently no distinction between cyber and conventional crime. However on a
deep introspection we may say that there exists a fine line of demarcation
between the conventional and cyber crime, which is appreciable. The demarcation
lies in the involvement of the medium in cases of cyber crime. The sine qua non for cyber crime is that
there should be an involvement, at any stage, of the virtual cyber medium.
REASONS
FOR CYBER CRIME:
Hart in
his work “ The Concept of Law” has said ‘human beings are vulnerable so rule of
law is required to protect them’. Applying this to the cyberspace we may say
that computers are vulnerable so rule of law is required to protect and
safeguard them against cyber crime. The reasons for the vulnerability of
computers may be said to be:
1.
Capacity to store data in
comparatively small space-
The computer has unique characteristic of
storing data in a very small space. This affords to remove or derive
information either through physical or virtual medium makes it much more
easier.
- Easy to access-
The problem encountered in guarding a computer system
from unauthorised access is that there is every possibility of breach not due
to human error but due to the complex technology. By secretly implanted logic
bomb, key loggers that can steal access codes, advanced voice recorders; retina
imagers etc. that can fool biometric systems and bypass firewalls can be
utilized to get past many a security system.
3.Complex-
The computers work on operating systems and these
operating systems in turn are composed of millions of codes. Human mind is
fallible and it is not possible that there might not be a lapse at any stage.
The cyber criminals take advantage of these lacunas and penetrate into the
computer system.
4.Negligence-
Negligence is very closely connected with human
conduct. It is therefore very probable that while protecting the computer
system there might be any negligence, which in turn provides a cyber criminal
to gain access and control over the computer system.
5. Loss of
evidence-
Loss of evidence is a very common & obvious
problem as all the data are routinely destroyed. Further collection of data
outside the territorial extent also paralyses this system of crime
investigation.
CYBER CRIMINALS:
The
cyber criminals constitute of various groups/ category. This division may be
justified on the basis of the object that they have in their mind. The
following are the category of cyber criminals-
1. Children
and adolescents between the age group of 6 – 18 years –
The simple reason for this type of delinquent
behaviour pattern in children is seen mostly due to the inquisitiveness to know
and explore the things. Other cognate reason may be to prove themselves
to be outstanding amongst other children in their group. Further the reasons
may be psychological even. E.g. the Bal
Bharati (Delhi)
case was the outcome of harassment of the delinquent by his friends.
2. Organised
hackers-
These kinds of hackers are mostly organised together
to fulfil certain objective. The reason may be to fulfil their political bias,
fundamentalism, etc. The Pakistanis are said to be one of the best quality
hackers in the world. They mainly target the Indian government sites with the
purpose to fulfil their political objectives. Further the NASA as well as the Microsoft sites is always under
attack by the hackers.
3. Professional hackers / crackers –
Their work is motivated by the colour
of money. These kinds of hackers are mostly employed to hack the site of the
rivals and get credible, reliable and valuable information. Further they are
ven employed to crack the system of the employer basically as a measure to make
it safer by detecting the loopholes.
4.
Discontented employees-
This group include those people who have been
either sacked by their employer or are dissatisfied with their employer. To
avenge they normally hack the system of their employee.
MODE AND
MANNER OF COMMITING CYBER CRIME:
- Unauthorized access to computer systems or networks / Hacking-
This
kind of offence is normally referred as hacking in the generic sense. However
the framers of the information technology act 2000 have no where used this term
so to avoid any confusion we would not interchangeably use the word hacking for
‘unauthorized access’ as the latter has wide connotation.
- Theft of information contained in electronic form-
This includes information stored in computer hard
disks, removable storage media etc. Theft may be either by appropriating
the data physically or by tampering them through the virtual medium.
- Email bombing-
This kind of activity refers to sending large numbers
of mail to the victim, which may be an individual or a company or even mail
servers there by ultimately resulting into crashing.
- Data diddling-
This kind of an attack involves altering raw data just
before a computer processes it and then changing it back after the processing
is completed. The electricity board
faced similar problem of data diddling while the department was being
computerised.
- Salami attacks-
This kind of crime is normally prevalent in the
financial institutions or for the purpose of committing financial crimes. An
important feature of this type of offence is that the alteration is so small
that it would normally go unnoticed. E.g. the Ziegler case wherein a logic bomb was introduced in the
bank’s system, which deducted 10 cents from every account and deposited it in a
particular account.
- Denial of Service attack-
The computer of the victim is flooded with more
requests than it can handle which cause it to crash. Distributed Denial of
Service (DDoS) attack is also a type of denial of service attack, in which the
offenders are wide in number and widespread. E.g. Amazon, Yahoo.
7. Virus / worm attacks-
Viruses are programs that attach themselves to a
computer or a file and then circulate themselves to other files and to other
computers on a network. They usually affect the data on a computer, either by
altering or deleting it. Worms, unlike viruses do not need the host to attach
themselves to. They merely make functional copies of themselves and do this
repeatedly till they eat up all the available space on a computer's memory.
E.g. love bug virus,
which affected at least 5 % of the computers of the globe. The losses were
accounted to be $ 10 million. The world's most famous worm was the Internet
worm let loose on the Internet by Robert
Morris sometime in 1988. Almost brought development of
Internet to a complete halt.
8. Logic bombs-
These are event dependent programs. This implies
that these programs are created to do something only when a certain event
(known as a trigger event) occurs. E.g. even some viruses may be termed logic
bombs because they lie dormant all through the year and become active only on a
particular date (like the Chernobyl virus).
- Trojan attacks-
This term
has its origin in the word ‘Trojan horse’. In software field this means an
unauthorized programme, which passively gains control over another’s system by
representing itself as an authorised programme. The most common form of
installing a Trojan is through e-mail. E.g. a Trojan was installed in the
computer of a lady film director
in the U.S.
while chatting. The cyber criminal through the web cam installed in the
computer obtained her nude photographs. He further harassed this lady.
- Internet time thefts-
Normally in these kinds of thefts the Internet surfing
hours of the victim are used up by another person. This is done by gaining
access to the login ID and the password. E.g. Colonel Bajwa’s case- the Internet hours were used up by any
other person. This was perhaps one of the first reported cases related to cyber
crime in India.
However this case made the police infamous as to their lack of understanding of
the nature of cyber crime.
11. Web
jacking-
This
term is derived from the term hi jacking. In these kinds of offences the hacker
gains access and control over the web site of another. He may even mutilate or
change the information on the site. This may be done for fulfilling political
objectives or for money. E.g. recently the site of MIT (Ministry of Information
Technology) was hacked by the Pakistani hackers and some obscene matter was
placed therein. Further the site of Bombay
crime branch was also web jacked. Another case of web jacking is that of the ‘gold fish’ case. In this case the
site was hacked and the information pertaining to gold fish was changed.
Further a ransom of US $ 1 million was demanded as ransom. Thus web jacking is
a process where by control over the site of another is made backed by some
consideration for it.
CLASSIFICATION:
The
subject of cyber crime may be broadly classified under the following three
groups. They are-
1. Against Individuals
a. their person &
b. their property of an individual
2.
Against Organization
a.
Government
c. Firm, Company, Group of Individuals.
3. Against Society at large
The
following are the crimes, which can be committed against the followings
group
Against Individuals: –
i.
Harassment via e-mails.
ii. Cyber-stalking.
iii. Dissemination of obscene material.
iv. Defamation.
v. Unauthorized control/access over computer system.
vi. Indecent exposure
vii. Email spoofing
viii. Cheating & Fraud
Against Individual Property: -
i. Computer vandalism.
ii. Transmitting virus.
iii. Netrespass
iv. Unauthorized control/access over computer system.
v. Intellectual Property crimes
vi. Internet time thefts
Against Organization: -
i.
Unauthorized control/access over computer system
ii. Possession of unauthorized information.
iii. Cyber terrorism against the government organization.
iv. Distribution of pirated software etc.
Against Society at large: -
i. Pornography (basically child pornography).
ii. Polluting the youth through indecent exposure.
iii. Trafficking
iv. Financial crimes
v.Sale of illegal articles
vi.Online gambling
vii. Forgery
The above mentioned offences may
discussed in brief as follows:
1.
Harassment via e-mails-
Harassment through e-mails is not a new concept. It is very similar to
harassing through letters. Recently I had received a mail from a lady wherein she complained about
the same. Her former boy friend was sending her mails constantly sometimes
emotionally blackmailing her and also threatening her. This is a very common
type of harassment via e-mails.
2. Cyber-stalking-
The Oxford
dictionary defines stalking as "pursuing stealthily". Cyber
stalking involves following a person's movements across the
Internet by posting messages (sometimes threatening) on the bulletin boards
frequented by the victim, entering the chat-rooms frequented by the victim,
constantly bombarding the victim with emails etc.
3. Dissemination of obscene material/ Indecent
exposure/ Pornography
(basically child pornography) / Polluting
through indecent exposure-
Pornography on the net may take various forms.
It may include the hosting of web site containing these prohibited materials.
Use of computers for producing these obscene materials. Downloading through the
Internet, obscene materials. These obscene matters may cause harm to the mind
of the adolescent and tend to deprave or corrupt their mind. Two known cases of
pornography are the Delhi
Bal Bharati case and the Bombay case wherein two Swiss couple
used to force the slum children for obscene photographs. The Mumbai police
later arrested them.
4. Defamation
It is an act of imputing any person with intent to
lower the person in the estimation of the right-thinking members of society
generally or to cause him to be shunned or avoided or to expose him to hatred,
contempt or ridicule. Cyber defamation is not different from conventional
defamation except the involvement of a virtual medium. E.g. the mail account of
Rohit was hacked and
some mails were sent from his account to some of his batch mates regarding his
affair with a girl with intent to defame him.
4.
Unauthorized control/access over computer system-
This activity is commonly referred to as
hacking. The Indian law has however given a different connotation to the term
hacking, so we will not use the term "unauthorized access"
interchangeably with the term "hacking" to prevent confusion as the
term used in the Act of 2000 is much wider than hacking.
5. E mail
spoofing-
A spoofed e-mail may be said to be one, which
misrepresents its origin. It shows it's origin
to be different from which actually it originates. Recently spoofed mails were
sent on the name of Mr. Na.Vijayashankar (naavi.org), which contained
virus.
Rajesh
Manyar, a graduate student at Purdue
University in Indiana, was arrested for threatening to
detonate a nuclear device in the college campus. The alleged e- mail was sent
from the account of another student to the vice president for student services.
However the mail was traced to be sent from the account of Rajesh Manyar.(15)
6.
Computer vandalism-
Vandalism
means deliberately destroying or damaging property of another. Thus computer
vandalism may include within its purview any kind of physical harm done to the
computer of any person. These acts may take the form of the theft of a
computer, some part of a computer or a peripheral attached to the computer or
by physically damaging a computer or its peripherals.
7.
Transmitting virus/worms-
This
topic has been adequately dealt herein above.
8. Intellectual Property crimes /
Distribution of pirated software-
Intellectual property consists of a bundle of
rights. Any unlawful act by which the owner is deprived completely or partially
of his rights is an offence. The common form of IPR violation may be said to be
software piracy, copyright infringement, trademark and service mark violation,
theft of computer source code, etc.
The Hyderabad
Court has in a land mark judgement has convicted three people and
sentenced them to six months imprisonment and fine of 50,000 each for
unauthorized copying and sell of pirated software. (16)
9.
Cyber terrorism against the government organization
At this
juncture a necessity may be felt that what is the need to distinguish between
cyber terrorism and cyber crime. Both are criminal acts. However there is a
compelling need to distinguish between both these crimes. A cyber crime is
generally a domestic issue, which may have international consequences, however
cyber terrorism is a global concern, which has domestic as well as
international consequences. The
common form of these terrorist attacks on the Internet is by distributed denial
of service attacks, hate websites and hate emails, attacks on sensitive
computer networks, etc. Technology savvy terrorists are using 512-bit
encryption, which is next to impossible to decrypt. The recent example may be
cited of – Osama Bin Laden,
the LTTE, attack on America’s army deployment system during Iraq war.
Cyber terrorism may be defined to be “ the premeditated use of disruptive
activities, or the threat thereof, in cyber space, with the intention to
further social, ideological, religious, political or similar objectives, or to
intimidate any person in furtherance of such objectives” (4)
Another definition may be attempted to
cover within its ambit every act of cyber terrorism.
A terrorist means a person
who indulges in wanton killing of persons or in violence or in disruption of
services or means of communications essential to the community or in damaging
property with the view to –
(1) putting the public or
any section of the public in fear; or
(2) affecting adversely the
harmony between different religious, racial, language or regional groups or castes
or communities; or
(3) coercing or overawing
the government established by law; or
(4) endangering the
sovereignty and integrity of the nation
and a cyber terrorist is the person who uses the
computer system as a means or ends to achieve the above objectives. Every act
done in pursuance thereof is an act of cyber terrorism.
10.Trafficking
Trafficking may assume different forms.
It may be trafficking in drugs, human beings, arms weapons etc. These forms of
trafficking are going unchecked because they are carried on under pseudonyms. A
racket was busted in Chennai where drugs were being sold under the pseudonym of
honey.
- Fraud &
Cheating
Online fraud and cheating is one of the most
lucrative businesses that are growing today in the cyber space. It may assume
different forms. Some of the cases of online fraud and cheating that have come
to light are those pertaining to credit card crimes, contractual crimes,
offering jobs, etc.
Recently
the Court of Metropolitan
Magistrate Delhi (17) found guilty a
24-year-old engineer working in a call centre, of fraudulently gaining the
details of Campa's credit card and bought a television and a cordless phone
from Sony website. Metropolitan magistrate Gulshan Kumar convicted Azim for
cheating under IPC, but did not send him to jail. Instead, Azim was asked to
furnish a personal bond of Rs 20,000, and was released on a year's probation.
STATUTORY
PROVISONS:
The
Indian parliament considered it necessary to give effect to the resolution by
which the General Assembly adopted Model Law on Electronic Commerce adopted by
the United Nations Commission on Trade Law. As a consequence of which the
Information Technology Act 2000 was passed and enforced on 17th May 2000.the
preamble of this Act states its objective to legalise e-commerce and further
amend the Indian Penal Code 1860, the Indian Evidence Act 1872, the Banker’s
Book Evidence Act1891 and the
Reserve Bank of India Act 1934. The basic purpose to incorporate the changes in these Acts is to make
them compatible with the Act of 2000. So that they may regulate and
control the affairs of the cyber world in an effective manner.
The Information Technology Act deals
with the various cyber crimes in chapters IX & XI. The important sections
are Ss. 43,65,66,67. Section 43 in particular deals with the unauthorised
access, unauthorised downloading, virus attacks or any contaminant, causes
damage, disruption, denial of access, interference with the service availed by
a person. This section provide for a fine up to Rs. 1 Crore by way of remedy.
Section 65 deals with ‘tampering with
computer source documents’ and provides for imprisonment up to 3 years
or fine, which may extend up to 2 years or both. Section 66 deals with ‘hacking with computer system’ and provides
for imprisonment up to 3 years or fine, which may extend up to 2 years or both.
Further section 67 deals with publication of obscene material and provides for
imprisonment up to a term of 10 years and also with fine up to Rs. 2 lakhs. (14)
ANALYSIS OF THE
STATUTORY PROVISONS:
The
Information Technology Act 2000 was undoubtedly a welcome step at a time when
there was no legislation on this specialised field. The Act has however during
its application has proved to be inadequate to a certain extent. The various
loopholes in the Act are-
1. The hurry in which the legislation was
passed, without sufficient public debate, did not really serve the
desired purpose (6)-
Experts
are of the opinion that one of the reasons for the inadequacy of the legislation
has been the hurry in which it was passed by the parliament and it is also a
fact that sufficient time was not given for public debate.
2.
“Cyberlaws,
in their very preamble and aim, state that they are targeted at aiding
e-commerce, and are not meant to regulate cybercrime”(6) –
Mr. Pavan Duggal
holds the opinion that the main intention of the legislators has been to
provide for a law to regulate the e-commerce and with that aim the I.T.Act 2000
was passed, which also is one of the reasons for its inadequacy to deal with
cases of cyber crime.
At this point I would like to express my
respectful dissent with Mr. Duggal. I feel that the above statement by Mr.
Duggal is not fundamentally correct. The reason being that the preamble does
state that the Act aims at legalising e-commerce. However it does not stop
here. It further amends the I.P.C., Evidence Act, Banker’s Book Evidence and
RBI Act also. The Act also aims to deal with all matters connected therewith or
incidental thereto. It is a cardinal rule of interpretation that “text should be read as a whole to gather the
meaning”. It seems that the above statement has been made in total disregard of
this rule of interpretation. The preamble, if read as a whole,
makes it very clear that the Act equally aims at legalising e-commerce and to
curb any offences arising there from.
3.Cyber torts-
The
recent cases including Cyber stalking cyber harassment, cyber nuisance, and
cyber defamation have shown that the I.T.Act 2000 has
not dealt with those offences. Further it is also contended that in future new
forms of cyber crime will emerge which even need to be taken care
of. Therefore India
should sign the cyber crime convention. However the I.T.Act 2000 read with the
Penal Code is capable of dealing with these felonies.
4.Cyber crime in the Act is neither
comprehensive nor exhaustive-
Mr. Duggal believes that
we need dedicated legislation on cyber crime that can supplement the Indian
Penal Code. The contemporary view is held by Mr. Prathamesh Popat who has
stated- "The IT Act, 2000 is not comprehensive enough and doesn't even
define the term 'cyber crime".
(8) Mr. Duggal has
further commented, “India, as a nation, has to cope with an urgent need to regulate
and punish those committing cyber crimes, but with no specific provisions to do
so. Supporters of the Indian
Penal Code
School vehemently argue
that IPC has stood the test of time and that it is not necessary to incorporate
any special laws on cyber crime. This is because it is debated by them that the
IPC alone is sufficient for all kinds of crime. However, in practical terms,
the argument does not have appropriate backing. It has to be distinctly
understood that cyber crime and cyberspace are completely new whelms, where
numerous new possibilities and opportunities emerge by the day in the form of
new kinds of crimes.”(6)
I feel that a new legislation on cyber
crime is totally unwarranted. The reason is that the new legislation not come
alone but will bring with it the same confusion, the same dissatisfaction and
the same desire to supplant it by further new legislation. Mr. Duggal has
stated above the need to supplement IPC by a new legislation. If that is the
issue then the present legislation along with the Penal Code when read
harmoniously and co- jointly is sufficient to deal with the present problems of
cyber crime. Further there are other legislations to deal with the intellectual
property crimes on the cyber space such as the Patents Act, Copy Right Act,
Trade Marks Act.
5.Ambiguity in the definitions-
The definition of hacking provided in section 66 of the Act is
very wide and capable of misapplication. There is every possibility of this
section being misapplied and in fact the Delhi
court has misapplied it. The infamous go2nextjob has made it very clear that
what may be the fate of a person who is booked under section 66 or the constant
threat under which the netizens are till s. 66 exists in its present form.
Further section 67 is also vague to
certain extent. It is difficult to define the term lascivious information or obscene pornographic information. Further
our inability to deal with the cases of cyber pornography has been proved
by the Bal Bharati case.
6. Uniform law-
Mr. Vinod Kumar (9)
holds the opinion that the need of the hour is a worldwide uniform cyber law
to combat cyber crime. Cyber crime is a global phenomenon and therefore the
initiative to fight it should come from the same level. E.g. the author of the
love bug virus was appreciated by his countrymen.
7.Lack of awareness-
One important reason that the Act of 2000 is not
achieving complete success is the lack of awareness among the s about their
rights. Further most of the cases are going unreported. If the people are
vigilant about their rights the law definitely protects their right. E.g. the Delhi high court in
October 2002 prevented a person from selling Microsoft pirated software over an auction site. Achievement
was also made in the case before the court of metropolitan magistrate Delhi wherein a person
was convicted for online cheating by
buying Sony products using a stolen
credit card. (17)
8. Jurisdiction issues-
Jurisdiction is also one of the debatable
issues in the cases of cyber crime due to the very universal nature of cyber
space. With the ever-growing arms of cyber space the territorial concept seems
to vanish. New methods of dispute resolution should give way to the
conventional methods. The Act of 2000 is very silent on these issues.
9. Extra territorial application-
Though S.75 provides for extra-territorial operations
of this law, but they could be meaningful only when backed with provisions
recognizing orders and warrants for Information issued by competent
authorities outside their jurisdiction and measure for cooperation for exchange
of material and evidence of computer crimes between law enforcement agencies.
10. Raising a cyber army-
By
using the word ‘cyber army’ by no means I want to convey the idea of virtual
army, rather I am laying emphasis on the need for a well equipped task force to
deal with the new trends of hi tech crime. The government has taken a leap in
this direction by constituting cyber crime cells in all metropolitan and other
important cities. Further the establishment of the Cyber Crime Investigation Cell (CCIC) of the
Central Bureau of Investigation (CBI) 11) is
definitely a welcome step in this direction. There are man cases in which the
C.B.I has achieved success. The present position of cases of cyber crime (17) is –
Case 1: When a woman at an MNC started receiving obscene
calls, CBI found her colleague had posted her personal details on
Mumbaidating.com.
Status: Probe on
Case 2: CBI arrested a man from UP, Mohammed Feroz, who
placed ads offering jobs in Germany.
He talked to applicants via e-mail and asked them to deposit money in his bank
account in Delhi.
Status: Chargesheet not
filed
Case 3: The official web-site of the Central Board of Direct
Taxes was hacked last year. As Pakistan-based hackers were responsible,
authorities there were informed through Interpol.
Status: Pak not
cooperating.
11. Cyber savvy bench-
Cyber savvy judges are the need of the day. Judiciary plays a
vital role in shaping the enactment according to the order of the day. One such
stage, which needs appreciation, is the P.I.L., which the Kerela High Court has accepted
through an email. The role of the judges in today’s word may be gathered by the
statement- judges carve ‘law is’ to ‘law ought to be’. Mr T.K.Vishwanathan, member
secretary, Law Commission
, has highlighted the requirements for introducing e-courts in India. In his
article published in The Hindu he has stated “if there is one area of Governance where IT can make a huge difference
to Indian public is in the Judicial System”.
12. Dynamic form of cyber crime-
Speaking on the dynamic nature of cyber crime FBI Director
Louis Freeh has said, "In short,
even though we have markedly improved our capabilities to fight cyber
intrusions the problem is growing even faster and we are falling further behind.” The (de)creativity
of human mind cannot be checked by any law. Thus the only way out is the
liberal construction while applying the statutory provisions to cyber crime
cases.
13. Hesitation to report offences-
As stated above one of the fatal drawbacks of the Act has
been the cases going unreported. One obvious reason is the non-cooperative
police force. This was proved by the Delhi time theft case. "The
police are a powerful force today which can play an instrumental role in
preventing cybercrime. At the same time, it can also end up wielding the rod
and harassing innocent s, preventing them from going about their normal cyber
business."(10) This
attitude of the administration is also revelled by incident that took place at Merrut and Belgam. (for the
facts of these incidents refer to naavi.com). For complete realisation of the
provisions of this Act a cooperative police force is require.
PREVENTION OF CYBER CRIME:
Prevention
is always better than cure. It is always better to take certain precaution
while operating the net. A should make them his part of cyber life.
Saileshkumar Zarkar, technical advisor and network security consultant to the
Mumbai Police Cyber crime Cell, advocates the 5P mantra for online security: Precaution, Prevention, Protection,
Preservation and Perseverance. A netizen should keep in mind the
following things-
1.to prevent cyber stalking avoid disclosing any information pertaining
to oneself. This is as good as disclosing your identity to strangers in public
place.
2.always avoid sending any photograph online particularly to strangers
and chat friends as there have been incidents of misuse of the photographs.
3.always use latest and up date anti virus software to guard against
virus attacks.
4.always keep back up volumes so that one may not suffer data loss in
case of virus contamination
5.never send your credit card number to any site that is not secured, to
guard against frauds.
6.always keep a watch on the sites that your children are accessing to
prevent any kind of harassment or depravation in children.
7.it is better to use a security programme that gives control over the
cookies and send information back to the site as leaving the cookies unguarded
might prove fatal.
8.web site owners should watch traffic and check any irregularity on the
site. Putting host-based intrusion detection devices on servers may do this.
9.use of firewalls may be beneficial.
10. web servers running public sites must be physically separate
protected from internal corporate network.
Adjudication of a Cyber Crime - On the directions of
the Bombay High Court the Central Government has by a notification dated
25.03.03 has decided that the Secretary to the Information Technology
Department in each state by designation would be appointed as the AO for each
state.
CONCLUSION:
Capacity
of human mind is unfathomable. It is not possible to eliminate cyber crime from
the cyber space. It is quite possible to check them. History is the witness
that no legislation has succeeded in totally eliminating crime from the globe.
The only possible step is to make people aware of their rights and duties (to
report crime as a collective duty towards the society) and further making the
application of the laws more stringent to check crime. Undoubtedly the Act is a
historical step in the cyber world. Further I all together do not deny that
there is a need to bring changes in the Information Technology Act to make it
more effective to combat cyber crime. I would conclude with a word of caution for
the pro-legislation school that it should be kept in mind that the provisions
of the cyber law are not made so stringent that it may retard the growth of the
industry and prove to be counter-productive.
