Cryptography and network security descries the security parameter with the help of public and private key. Digital signature is one of the most important area which we apply in our daily life for transferring the data.

1. By
Department of Computer Sc. & Engineering
Cryptography and Network Security
NIT- 701
Presented By
Amit Kumar Pathak

2. Learning Objective
• To familiarize with the security parameters in
computer networks
• The way of develop the algorithm in various
ways.
• General type of network security and their
implementation
• How to secure our network via different
algorithms.

3. Discussion Goals
• Cryptography – Definition.
• History of Cryptography.
• Basic Terminologies.
• Importance of Cryptography.
• Types of Cryptography.
• Cryptography Algorithms.
– RSA (Public Key)
– DES (Symmetric)
• Hash Functions
• Digital Signatures
• Watermarking

4. What is Cryptography ?
“Cryptography is an art of Secret writing”
Or
“Cryptography -- from the Greek for “secret writing”
(Kryptos means ‘HIdden’, graphein means ‘writing’) -- is
the mathematical “scrambling” of data into unreadable
form to preserve confidentiality. ”
Or
“Cryptography is the process of converting plaintext into
ciphertext”

5. Base Cryptography Mechanism
Encryption
Algorithmplaintext
Ciphertext
plaintext
Juvia
Gray
Decryption
Algorithm
Key A Key B

6. Cryptography Issues
CIA Traid

7. Confidentiality: only sender, intended receiver should
“understand” message contents.
sender encrypts message.
receiver decrypts message.
End-Point Authentication: sender, receiver want to confirm
identity of each other.
Message Integrity: sender, receiver want to ensure message
not altered (in transit, or afterwards) without detection.

8. History of Crytography
• There are three eras in the history of Cryptography:
– The Manual era
– The Mechanical era
– The Modern era
• Manual era refers to Pen and Paper Cryptography and dates back to 2000
B.C.eg : Scytale, Atbash , Caesar, Vigenere.
• Mechanical era refers to the invention of cipher machines. E.g.: Japanese
Red and Purple Machines , German Enigma.
• The modern era of cryptography refers to computers.
• There are infinite permutations of cryptography available using
computers. E.g.: Lucifer, Rijndael , RSA , ElGamal.
8

9. BASIC TERMINOLOGIES

10. Basic Terms
Cipher: the algorithm that does the encryption.
Ciphertext: the encrypted (scrambled) version of the
message. Message altered to be unreadable by anyone
except the intended recipients.
Cryptanalysis: the science of breaking cryptographic
algorithms.
Cryptanalyst: a person who breaks cryptographic codes;
also referred to as “the attacker”.

11.  Cryptosystem – The combination of algorithm, key, and key
management functions used to perform cryptographic
operations.
 Decryption: the process of converting ciphertext back to
the original plaintext.
 Encryption: scrambling a message or data using a
specialized cryptographic algorithm.
 Initialization Vector – Random values used with ciphers to
ensure no patterns are created during encryption.
5

12. Key – Sequence that controls the operation and behavior of the
cryptographic algorithm.
Keyspace – Total number of possible values of keys in a crypto
algorithm.
Plaintext – A message in its natural format readable by an
attacker.
12

13. Cryptosystem Services or Security
Goals
Authentication
– Ensures that whoever supplies or accesses sensitive data is
an authorized party.
Confidentiality
– Assures that only authorized parties are able to understand
the data.

14. Integrity
– Ensures that when a message is sent over a network, the
message that arrives is the same as the message that was
originally sent.
Nonrepudiation
– Ensuring that the intended recipient actually received the
message & ensuring that the sender actually sent the
message.

15. Importance of Cryptography

16. Need for Cryptography
• Establishing a Secure communication.
• Fulfil the security goals.
• Preservation of Authentic information.
• Secure Transaction.
• Privacy.

17. Attributes of Strong Encryption
• Confusion
– Change key values each round
– Performed through substitution
– Complicates plaintext/key relationship
• Diffusion
– Change location of plaintext in ciphertext
– Done through transposition
17

18. Types of Cryptography

19. Encryption Systems
• Substitution Cipher
– Convert one letter to another
– Cryptoquip
• Transposition Cipher
– Change position of letter in text
– Word Jumble
• Monoalphabetic Cipher
– Caesar
19

20. Encryption Systems
• Polyalphabetic Cipher
–Vigenère
• Modular Mathematics
–Running Key Cipher
• One-time Pads
–Randomly generated keys
20

21. Categories of Cryptography
Traditional
• Cryptography in its early days
• Ex :- Caesar Cipher, Playfair, Rain fence
Symmetric
• Shared Key
• Ex :- DES, AES etc.
Public Key
• Public and Private Key.
• Ex : - RSA, ElGamal etc.

22. Traditional Cryptography
Cryptography in its early stages.

23. Caesar Cipher
• Caesar cipher is named after the Roman military and
political leader Gaius Julius Caesar (100 BC – 44 BC).1
Caesar used this relatively simple form of ciphering to
encode military messages.
• Every character C in the message M is replaced by (C+3)
Scheme
A B C D E …..
D E F G H …..
Example :-
Plaintext = “DAD”
Ciphertext = “GDG”

24. Rail Fence Cipher
• Plaintext is written in successive ‘rails’ diagonally.
• No. of rails is predefined, say 3.
• After the message exhausts on rails the message is
read row-wise and it becomes the cipher text.
For example, if we have 3 "rails" and a message of
'WE ARE DISCOVERED. FLEE AT ONCE', the cipher
writes out:
W . . . E . . . C . . . R . . . L . . . T . . . E
. E . R . D .S . O . E . E . F . E . A . O . C .
. . A . . . I . . . V . . . D . . . E . . . N . .
Cipher Text : WECRL TEERD SOEEF EAOCA IVDEN

25. Kamasutra Cipher
• The Kamasutra cipher is one of the earliest known
substitution methods.
• The purpose was to teach women how to hide secret
messages from prying eyes.
Principle
The key is the permutation of the alphabet. The
plaintext and the ciphertext alphabet are the same. The
alphabet is divided in two halves to pair the letters:
F Y M Q G V O P D J R A K
C I E U B X T S Z W N L H
The letter “F” becomes the letter “C” and “B” is replaced
by “G”. The word "EXAMPLE" would be encoded by:
"MVLESAM".

26. Enigma
• Used by the Germans
during World War II
– Replaced letters as they
were typed
– Substitutions were
computed using a key
and a set of switches or
rotors.
26

27. Symmetric Key Cryptography

28. Symmetric Key Scheme
– Same key for encryption and decryption
– Key distribution problem
• Cleartext with Key makes Ciphertext
• Ciphertext with Key makes Cleartext
28
Winning Lotto #s: aWDHOP#@-w9
aWDHOP#@-w9 Winning Lotto #s:

29. ..contd.
• Advantages
– Symmetric algorithms are fast
– They are difficult to break if a large key size is used
– Only one key needed
29

30. ..contd.
• Disadvantages
– Symmetric keys must remain secret
– Difficult to deliver keys (key distribution)
– Symmetric algorithms don’t support authenticity
or nonrepudiation
• You can’t know for sure who sent the message, since
two people have the same key
30

31. Symmetric Cryptography Algorithms
• Types of symmetric algorithms
– Stream ciphers
• Operate on plaintext one bit at a time
– Block ciphers
• Operate on blocks of plaintext
31

32. Symmetric Algorithms
• DES
–Modes: ECB, CBC, CFB, OFB, CM
• 3DES
• AES
• IDEA
• Blowfish
32

33. ..contd.
• RC4
• RC5
• CAST
• SAFER
• Twofish
33

34. Key Distribution
• Symmetric schemes require both parties to share a common
secret key
• issue is how to securely distribute this key
• often secure system failure due to a break in the key
distribution scheme

35. Key Distribution methods
• Given parties A and B have various
key distribution alternatives:
1. A can select key and physically deliver to
B
2. third party can select & physically deliver
key to A & B
3. if A & B have communicated previously
can use previous key to encrypt a new
key
4. if A & B have secure communications
with a third party C, C can relay key
between A & B
Not suitable
for large
systems
Initial
distribution?

36. Scale of key distribution problem
• A network with N hosts
=> N(N-1)/2 pairs
• Node-level encryption
N(N-1)/2
• Application-level
encryption
– 10 applications/node

37. Key distribution center (KDC)
Key distribution
center (KDC)
KDC shares a unique key (master key) with each user to distribute
secret key (session key) between a pair of users:
scale of key distribution problem reduces to N
EMK1 (Secret key)
Secret key Secret key
EMK2 (Secret key)

38. Key Distribution Scenario
nonce: an identifier
that differs for each request
Session key Identifier for A (ex. address)
Master key Ka Master key Kb
(avoid replay attack)
1. Verify the original request
2. Avoid replay attack

39. Hierarchical key control
…
KDC
…
KDC
KDC
a b

40. Design Principles of DES
To achieve high degree of diffusion and confusion.
Diffusion: making each plaintext bit affect as many
ciphertext bits as possible.
Confusion: making the relationship between the encryption
key and the ciphertext as complex as possible.
1

41. DES: The Data Encryption Standard
• Most widely used block cipher in the world.
• Adopted by NIST in 1977.
• Based on the Feistel cipher structure with 16 rounds
of processing.
• Block = 64 bits
• Key = 56 bits
• What is specific to DES is the design of the F function
and how round keys are derived from the main key.
41

42. 42

43. Initial Permutation IP
• IP: the first step of the encryption.
• It reorders the input data bits.
• The last step of encryption is the inverse of IP.

44. Round Keys Generation
• Main key: 64 bits.
• 56-bits are selected and permuted using Permuted Choice
One (PC1); and then divided into two 28-bit halves.
• In each round:
– Left-rotate each half separately by either 1 or 2
bits according to a rotation schedule.
– Select 24-bits from each half, and permute the
combined 48 bits.
– This forms a round key.

45. 45
Permuted Choice One (PC1)
57 49 41 33 25 17 9
1 58 50 42 34 26 18
10 2 59 51 43 35 27
19 11 3 60 52 44 36
63 55 47 39 31 23 15
7 62 54 46 38 30 22
14 6 61 53 45 37 29
21 13 5 28 20 12 4

46. Round i
+
F
Li-1 Ri-1
ki
Li Ri
32
48
3232

47. TCP/IP Protocol Suite 47

48. 48
  
The and each have 32 bits, and the round key 48 bits.
The function, on input and , produces 32 bits:
( , )
where :
(
expands 32 bits o 4
)
t
The function of DES
L R K
F R K
F R K P S E K
E
R
F



8 bits;
: shrinks it back to 32 bits;
: permutes the 32 bits.
S
P

49. Public Key Cryptography

50. Public-Key Cryptography
• probably most significant advance in the 3000 year
history of cryptography
• uses two keys – a public key and a private key
• asymmetric since parties are not equal
• uses clever application of number theory concepts to
function
• complements rather than replaces private key
cryptography

51. ..contd.
• public-key/two-key/asymmetric cryptography
involves the use of two keys:
– a public-key, which may be known by anybody, and can be
used to encrypt messages, and verify signatures
– a private-key, known only to the recipient, used to decrypt
messages, and sign (create) signatures
• is asymmetric because
– those who encrypt messages or verify signatures cannot
decrypt messages or create signatures

52. ..contd.

53. Comparison between symmetric and
public-key encryption

54. Requirement for public-key cryptography
• Diffie and Hellman (1976) proposed the system
without the algorithm for E and D. They laid out the
requirement:
– It is computationally easy to generate a pair of keys
– It is computationally easy for a sender to encrypt
– It is computationally easy for a receiver to decrypt
– It is computationally infeasible for an opponent, knowing
the public key, to determine the private key
– It is computationally infeasible for an opponent, knowing
the public key and ciphtertext, to recover the plaintext
Y = EKU (X)b
X = DKR (Y)
b

55. Why Public-Key Cryptography?
• developed to address two key issues:
– key distribution – how to have secure communications in
general without having to trust a KDC with your key
– digital signatures – how to verify a message comes intact
from the claimed sender
• public invention due to Whitfield Diffie & Martin
Hellman at Stanford U. in 1976
– known earlier in classified community

56. Asymmetric Algorithms
• Diffie-Hellman
• RSA
• El Gamal
• Elliptic Curve Cryptography (ECC)
56

57. Public-Key Cryptosystems

58. Public-Key Applications
• can classify uses into 3 categories:
– encryption/decryption (provide secrecy)
– digital signatures (provide authentication)
– key exchange (of session keys)
• some algorithms are suitable for all uses, others are
specific to one

59. Security of Public Key Schemes
• like private key schemes brute force exhaustive
search attack is always theoretically possible
• but keys used are too large (>512bits)
• security relies on a large enough difference in
difficulty between easy (en/decrypt) and hard
(cryptanalyse) problems
• more generally the hard problem is known, its just
made too hard to do in practise
• requires the use of very large numbers
• hence is slow compared to private key schemes

60. RSA
• by Rivest, Shamir & Adleman of MIT in 1977
• best known & widely used public-key scheme
• based on exponentiation in a finite (Galois) field over
integers modulo a prime
– nb. exponentiation takes O((log n)3) operations (easy)
• uses large integers (eg. 1024 bits)
• security due to cost of factoring large numbers
– nb. factorization takes O(e log n log log n) operations (hard)

61. RSA Key Setup
• each user generates a public/private key pair by:
• selecting two large primes at random - p, q
• computing their system modulus N=p.q
– note ø(N)=(p-1)(q-1)
• selecting at random the encryption key e
• where 1<e<ø(N), gcd(e,ø(N))=1
• solve following equation to find decryption key d
– e.d=1 mod ø(N) and 0≤d≤N
• publish their public encryption key: KU={e,N}
• keep secret private decryption key: KR={d,p,q}

62. RSA Use
• to encrypt a message M the sender:
– obtains public key of recipient KU={e,N}
– computes: C=Me mod N, where 0≤M<N
• to decrypt the ciphertext C the owner:
– uses their private key KR={d,p,q}
– computes: M=Cd mod N
• note that the message M must be smaller than the modulus N
(block if needed)

63. Why RSA Works
• because of Euler's Theorem:
• aø(n)mod N = 1
– where gcd(a,N)=1
• in RSA have:
– N=p.q
– ø(N)=(p-1)(q-1)
– carefully chosen e & d to be inverses mod ø(N)
– hence e.d=1+k.ø(N) for some k
• hence :
Cd = (Me)d = M1+k.ø(N) = M1.(Mø(N))q
= M1.(1)q = M1 = M mod N

64. RSA Example
1. Select primes: p=17 & q=11
2. Compute n = pq =17×11=187
3. Compute ø(n)=(p–1)(q-1)=16×10=160
4. Select e : gcd(e,160)=1; choose e=7
5. Determine d: de=1 mod 160 and d < 160
Value is d=23 since 23×7=161= 10×160+1
6. Publish public key KU={7,187}
7. Keep secret private key KR={23,17,11}

65. RSA Example cont
• sample RSA encryption/decryption is:
• given message M = 88 (nb. 88<187)
• encryption:
C = 887 mod 187 = 11
• decryption:
M = 1123 mod 187 = 88

66. Exponentiation
• can use the Square and Multiply Algorithm
• a fast, efficient algorithm for exponentiation
• concept is based on repeatedly squaring base
• and multiplying in the ones that are needed to
compute the result
• look at binary representation of exponent
• only takes O(log2 n) multiples for number n
– eg. 75 = 74.71 = 3.7 = 10 mod 11
– eg. 3129 = 3128.31 = 5.3 = 4 mod 11

67. Exponentiation

68. RSA Key Generation
• users of RSA must:
– determine two primes at random - p, q
– select either e or d and compute the other
• primes p,q must not be easily derived from
modulus N=p.q
– means must be sufficiently large
– typically guess and use probabilistic test
• exponents e, d are inverses, so use Inverse
algorithm to compute the other

69. RSA Security
• three approaches to attacking RSA:
– brute force key search (infeasible given size of
numbers)
– mathematical attacks (based on difficulty of
computing ø(N), by factoring modulus N)
– timing attacks (on running of decryption)

70. Factoring Problem
• mathematical approach takes 3 forms:
– factor N=p.q, hence find ø(N) and then d
– determine ø(N) directly and find d
– find d directly
• currently believe all equivalent to factoring
– have seen slow improvements over the years
• as of Aug-99 best is 130 decimal digits (512) bit with GNFS
– biggest improvement comes from improved algorithm
• cf “Quadratic Sieve” to “Generalized Number Field Sieve”
– barring dramatic breakthrough 1024+ bit RSA secure
• ensure p, q of similar size and matching other constraints

71. Hashing Algorithms
• HAVAL
– Computes between 128 and 256 bit hash
– Between 3 and 5 rounds
• RIPEMD-160
– Developed in Europe published in 1996
– Patent-free
71

72. Digital Signatures
• Digital signatures can be permanently tied to the content of
the message being signed. They cannot then be 'moved' from
one document to another, for any attempt will be detectable.
• RSA and DSA are two of the most popular digital signature
schemes.

73. ..contd.
• In digital signature schemes, there are two algorithms: one
for signing, in which a secret key is used to process the
message and one for verification, in which the matching
public key is used with the message to check the validity of
the signature.

74. Watermarking
• Traditionally, a watermark has been used to
verify the authenticity of a document.

75. ..contd.
• Driver’s Licenses, diplomas, official letterhead were the
primary applications of watermarks .
• More recently, used to track or prevent redistribution of TV
logos.

76. ..contd.
Purpose of using:
– Ensure authenticity of digital goods.
– Prevent unauthorized use/ensures copyright.
– Prevent copying.
 Adding the watermark to the image itself
prevents removal by changing the format.
E.g. GIF->JPEG.

77. Steganography
A Smart way to hide data

78. Topics To Discuss
1. What is Steganography?
2. History Of Steganography
3. Technique
4. Basic Steganography Model
5. Steganography Terms
6. Types of Stegosystems
7. Types of Steganograph
8. Comparison of various Security techniques
9. Crypto-Steganography – A new approach
10. Applications
11. Comparison of various Secret Communication Techniques.
12. Steganography Tools
13. Future Scope
14. Conclusion
15. References

79. What is Steganography?
• Steganography is the art and science of writing hidden messages in
such a way that no one, apart from the sender and intended recipient,
suspects the existence of the message, a form of security through
obscurity.
STEGONOGRA
PHY
EXAMPLE
RANDOM TEXT
Since everyone can read,
encoding text
in neutral sentences is
doubtfully effective
SOME HIDDEN
PATTERN
Since Everyone Can Read,
Encoding Text
In Neutral Sentences Is
Doubtfully Effective
ORIGINAL MESSAGE SECRET INSIDE

80. History Of Steganography
• The first recorded uses of steganography can be traced back
to 440 BC when Herodotus mentions two examples of
steganography in his Histories.
• Ancient Greeks used Wax tablets as reusable writing surfaces,
sometimes used for shorthand.
• Ancient Chinese wrote messages on fine silk, which was then
crunched into a tiny ball and covered in wax.
• Special inks were important steganographic tools even during
Second World War.

81. Techniques
PHYSICAL TECHNIQUES:
• Hidden messages on paper written in secret inks under other messages or
on the blank parts of other messages.
• Hidden messages within wax tablets.
• Messages written on envelopes in the area covered by postage stamps.
DIGITAL TECHNIQUES:
• Concealing data within encrypted data or within random data (an
unbreakable cipher like the one-time pad generates cipher texts that look
perfectly random if one does not have the private key).
• Concealed messages in tampered executable files, exploiting redundancy
in the targeted instruction set.
• Pictures embedded in video material (optionally played at slower or faster
speed).

82. Basic Steganography Model
Secret
Message
Cover
Medium
Stego
Decoder
Key Cover
Estimate
of
Message
Original
Cover
Stego
Encoder
Communicationchannel

83. Steganography Terms
• Carrier or Cover File - A Original message or a file in
which hidden information will be stored inside of it .
• Stego-Medium - The medium in which the
information is hidden.
• Embedded or Payload - The information which is to
be hidden or concealed.
• Steganalysis - The process of detecting hidden
information inside a file.

84. Types Of Stegosystems and
Steganography
STEGOSYSTEM TYPES:
• Pure stegosystems - no key is used.
• Secret-key stegosystems - secret key is used.
• Public-key stegosystems - public key is used.
STEGANOGRAPHY TYPES:
–Text Steganography.
–Image Steganography.
–Audio Steganography.
–Video Steganography.
–Protocol Steganography.

85. Text Steganography
• Text steganography can be applied in the digital makeup
format such as PDF, digital watermark or information hiding
• It is more difficult to realize the information hiding based on
text. The simplest method of information hiding is to select
the cover first, adopt rules to add the phraseological or
spelling mistakes, or replace with synonymy words.
VARIOUS TEXT STEGANOGRAPHY METHODS:
• Line shifting Method
• Word shifting
• Open spaces
• Semantic methods
• Character Encoding

86. Examples of Text Steganography
• Minor changes to shapes of characters

87. Examples of Text Steganography

88. Image Steganography
• Using image files as hosts for steganographic messages takes advantage of the
limited capabilities of the human visual system
• Some of the more common method for embedding messages in image files can
be categorized into two main groups, image domain methods and transform
domain methods
Image And Transform Domain:
• Image – also known as spatial – domain techniques embed messages in the
intensity of the pixels directly, while for transform – also known as frequency –
domain, images are first transformed and then the message is embedded in the
image
• Image domain techniques encompass bit-wise methods that apply bit insertion
and noise manipulation and are sometimes characterized as “simple systems”
• Steganography in the transform domain involves the manipulation of
algorithms and image transforms

89. LSB [Least Significant bit]
Method
• Least significant bit (LSB) insertion is a common,
simple approach to embedding information in a cover
image
• The least significant bit (in other words, the 8th bit) of
some or all of the bytes inside an image is changed to
a bit of the secret message
• When using a 24-bit image, a bit of each of the red,
green and blue color components can be used, since
they are each represented by a byte. In other words,
one can store 3 bits in each pixel. An 800 × 600 pixel
image, can thus store a total amount of 1,440,000 bits
or 180,000 bytes of embedded data
• In its simplest form, LSB makes use of BMP images,
since they use lossless compression

90. • A grid for 3 pixels of a 24-bit image can be as follows:
(00101101 00011100 11011100)
(10100110 11000100 00001100)
(11010010 10101101 01100011)
• When the number 200, which binary representation is
11001000, is embedded into the least significant bits of
this part of the image, the resulting grid is as follows:
(00101101 00011101 11011100)
(10100110 11000101 00001100)
(11010010 10101100 01100011)

91. Example Of Image Steganography

92. Audio Steganography
• Embedding secret messages into digital sound is known as
audio Steganography.
• Audio Steganography methods can embed messages in
WAV, AU, and even MP3 sound files.
• The properties of the human auditory system (HAS) are
exploited in the process of audio Steganography
• To embed data secretly onto digital audio file there are few
techniques introduced :
– LSB Coding
– Phase Coding
– Parity Coding
– Spread Spectrum

93. Flowchart Of Audio
Steganography

94. Example of LSB Method
• The message 'HEY' is encoded in a
16-bit CD quality sample using
the LSB method.
• Here the secret information is
‘HEY’ and the cover file is audio
file. HEY is to be embedded inside
the audio file. First the secret
information ‘HEY’ and the audio
file are converted into bit stream.
• The least significant column of
the audio file is replaced by the
bit stream of sectet information
‘HEY’. The resulting file after
embedding secret information
‘HEY’ is called Stego-file.

95. Comparison of Secret
Communication Techniques
Communica
tion
Technique
Confidenti
ality
Integrity Availability
Cryptograph
y
  
Digital
Signatures
  
Steganograp
hy
  

96. Combined Crypto- Steganography
Plain Text
Stego
Image
Cipher
Text
Decrypti
on
Cipher
Text
Plain Text
Encryptio
n
Cover
Image

97. Applications
• Confidential communication and secret data storing
• Steganography provides us with:
• Potential capability to hide the existence of confidential
data
• Hardness of detecting the hidden (i.e., embedded) data
• Strengthening of the secrecy of the encrypted data
• Protection of data alteration
• Access control system for digital content distribution
• Media Database systems
• Usage in modern printers
• Alleged use by intelligence services

98. Steganography Tools
• Steganos
• S-Tools (GIF, JPEG)
• StegHide (WAV, BMP)
• Invisible Secrets (JPEG)
• JPHide
• Camouflage
• Hiderman

99. Future Scope
• Steganography, though is still a fairly new idea. There are constant
advancements in the computer field, suggesting advancements in
the field of steganography as well.
• It is likely that there will soon be more efficient and more advanced
techniques for Steganalysis.
• What is scary is that such a small file of only one or two sentences
may be all that is needed to commence a terrorist attack. In the
future, it is hoped that the technique of Steganalysis will advance
such that it will become much easier to detect even small messages
within an image.

100. Learning Outcomes
 Define the terms vulnerability, threat and attack.
 Identify physical points of vulnerability in simple networks
 Identify and classify particular examples of attacks
 Concepts of Digital Signature and their applications

101. Conclusion
• Interest in the use of steganography in our current digital age
can be attributed to both the desire of individuals to hide
communication through a medium rife with potential
listeners, or in the case of digital watermarking, the absolute
necessity of maintaining control over one’s ownership and the
integrity of data as it passes through this medium. This
increased interest is evidenced in the sheer number of
available tools to provide easy steganographic techniques to
the end user, as well as the proliferation of research and press
on the topic.