07-12-2012, 04:14 PM
Data Encryption Standard
Data Encryption Standard.docx (Size: 104.1 KB / Downloads: 22)
INTRODUCTION
OVER VIEW
Cryptology is the science of secret communication, which may be partitioned into cryptography and cryptanalysis. Cryptography deals with transformations of a message into coded form by encryption and the recovery of the original message by decryption. The result produced by encryption is called a cryptogram or cipher text. The set of data transformations used to do the encryption is called a cipher. Cryptanalysis deals with how to undo cryptographic communications by breaking a cipher or forging coded signals that may be encrypted as genuine. Cryptographic systems offer three important services: Secrecy, Authenticity and Integrity, which are the important security services to be provided for a communication system. Thus Cryptography plays an important role in the security of data transmission with the rapid growing number of Internet as well as wireless communication users.
There are several crypto algorithms in which Data Encryption Standard (DES) and Rivest-Shamir-Adleman (RSA) algorithms stand out as the most successful ones. Both of these crypto algorithms are block ciphers. They differ in the use of key i.e., DES algorithm uses a secret key whereas RSA algorithm uses public key. Later National Institute of Standards and Technology (NIST) accepted Advanced Encryption Standard (AES) as a FIPS standard in November 2001 [1]. This is due to some limitations present in the existing algorithms.
LIMITATIONS OF THE EXISTING SYSTEMS
The Data Encryption Standard expired in 1998 and the US National Institute of Standards and Technology (NIST) announced an open international competition for cipher designs to replace DES as the federal information processing standard. Rijndael won the competition based on security, simplicity, and suitability for both hardware and software implementations, and was designated the Advanced Encryption Standard. AES, like DES, is a symmetric key block cipher encryption algorithm. The basic operation of a symmetric key block cipher with 128 bit blocks and a 128 bit key
PROPOSED SYSTEM
Figure shows the architecture adopted in this paper. Sub Bytes and InvSubBytes transformations are merged using composite field arithmetic. Shift Rows and InvShiftRows are simple shifting transformations. Mix Column and InvMixColumn transformations are optimized and merged. The proposed architecture is different with previous work in [2]. In the decryption procedure the round key is added to the state first and then the result is applied with the InvMixcolumn transformation. In this way modified round keys mentioned above can share with the state using just one InvMixColumn.
AES ALGORITHM
In cryptography, the AES, also known as Rijndael, is a block cipher adopted as an encryption standard by the US government, which specifies an encryption algorithm capable of protecting sensitive information. The AES algorithm is a symmetric block cipher that can encrypt (encipher) and decrypt (decipher) information.
ENCRYPTION
Encryption converts data to an unintelligible form called cipher-text. Only the intended person can understand what it is. Here in this standard the encryption is done by using three transformations that is given by
a) Sub bytes transformation
b) Shift row transformation
c) Mix column transformation
d) Add round key
DECRYPTION
Decryption of the cipher-text converts the data back into its original form, which is called plaintext. The AES algorithm is capable of using cryptographic keys of 128, 192, and 256 bits to encrypt and decrypt data in
Blocks of 128 bits.
To achieve a high throughput up to tens of Gbps, pipelining, sub-pipelining and loop-unrolling architectures have been explored.
This project adopts iterative architecture to achieve small area, but the structure can be applied to pipelining and sub-pipelining easily to get a higher throughput for no LUTs or memory are used so that no unbreakable delay is introduced in the architecture.