In the internet & network application, the most challenging aspect is security. With the rapid growth of network and network applications, the security aspect comes first in mind. Cryptography is one of the data security measures. It is invaluable in e-banking, e-trading, and e-commerce. This project involved research and implementation of the three most common existing cryptographic algorithms: RSA, AES, and Blowfish. It was analyzed that given algorithms are the best algorithm for data security.

1. Cryptography and its Application in
Security
Guided by
Dr. T.J.Siddiqui
Akriti Gupta
Roll No.:- 04
M.Sc. 4th Sem

2. INTRODUCTION
CRYPTOGRAPHY IS THE SCIENCE OF PROTECTING DATA,
WHICH PROVIDES MEANS AND METHODS OF
CONVERTING DATA INTO UNREADABLE FORM, SO THAT
VALID USER CAN ACCESS INFORMATION AT THE
DESTINATION.

4. OBJECTIVE
Our main goal in this project is to study and implement existing
algorithms of cryptography. We will analyze the various
algorithms and then draw conclusion which algorithm is best for
data security. Implementation of algorithms of cryptography for
securing information includes any type of data-text, image.

5. SERVICES OF INFORMATION
SECURITY −
• Confidential
• Authentication
• Integrity
• Non-repudiation

6. Types of Cryptography
 Symmetric key cryptography
Single common key to encrypt and decrypt
Faster an Simpler
e.g. RSA Algorithm
 Asymmetric key cryptography
A pair of keys to use to encrypt and decrypt
Private and Public key are different.

7. METHDOLOGY
 RSA (Rivest-Shamir-Adleman )
 AES (Advanced Encryption
Standard)
 Blowfish

8. In 1977, Rivest, Shamir, and Adelman proposed a scheme using a
public key for encrypting messages and a corresponding private key
for decryption -this scheme is commonly referred to as RSA.
RSA operation
RSA algorithm is asymmetric cryptography algorithm. Asymmetric
actually means that it works on two different keys i.e. Public Key
and Private Key. As the name describes that the Public Key is
given to everyone and Private key is kept private.
RSA

9. Step 1: Choose two large prime numbers p and q. The product
n=p X q is referred to as the modulus and ∅(n).
Step 2: Choose an encryption key, e, such that gcd(e,∅(n))= 1.
The pair of integers,(e,n) is referred to as the Public key.
Step 3: Compute the decryption key, d= 𝑒−1
mod ∅(n). d is also
referred to as the private key.
Key generation

10. Encryption Let m be the message (or plaintext). We use 𝑚 to
denote the length of m. In the naive implementation of RSA, a
message is split into multiple blocks, each size b, except possibly
for last block. 𝑚 mod b, if different from 0,will be the size of the
last block . For each block 𝑚𝑖,calculate the corresponding
ciphertext 𝑐𝑖 as
𝑐𝑖=𝑚𝑖
𝑒
mod n (1)
Encryption

11. Decryption
Given block of ciphertext 𝑐𝑖, the corresponding plaintext is
𝑚𝑖=𝑐𝑖
𝑑
mod n (2)
A block of plaintext, 𝑚𝑖 is encrypted as 𝑐𝑖 using (1)

12. AES(advanced encryption standard)
Rijndael algorithm supports various blocks sizes-128,192, 256 bits.
Likewise, different key sizes may be used -128, 192 , or 256 bits.
AES employs 10 rounds for 128-bit keys, and 12 rounds for 192 and
14 rounds for 256 bit keys.
It is convenient to visualize a block (and its transformation during and
after each round) as a 4 X 4 array of bytes. We refer to this as the
state array and denote it as Ƭ.

13. Encryption
In the case of 128-bit AES, each round(except for last) employs the
following four steps :
1)Byte substitution
2)Row shift
3)Column mixing
4)Round key addition
The last round skips the “Column mixing” step. Also, there is a solitary
“Round key addition” step just before the first round.

14. Decryption
Decryption can proceed in the reverse order -from the 10th round
upwards with each step being substituted by its inverse operation.
We denote their inverses as
1) InverseByte substitution
2) InverseRow shift
3) InverseColumn mixing
4) InverseRound key addition

16. Blowfish
In 1993 an alternative to DES Encryption Technique Blowfish
is an encryption technique designed by Bruce Schneier .
Block Size: 64-bits
Key Size: 32-bits to 448-bits variable size
Number of subkeys: 18 [P-array]
Number of rounds: 16
Number of subsitution boxes: 4 [each having 512 entries of
32-bits each]

21. Thanks