Secret key Algorithms in Cryptography
Data security is very important in wireless network and for this cryptography plays a crucial role which means “secret writing”. In Cryptography encryption decryption of data is done by using secret key to provide data confidentiality, data integrity and data authentication.
Cryptography, a word with Greek origins, means “secret writing” is the science of devising methods that allow for information to be sent in a secure form in such a way that the only person able to retrieve this information is the intended recipient. The message to be sent through an unreliable medium is known as plaintext, which is encrypted before sending over the medium. The encrypted message is known as cipher text, which is received at the other end of the medium and decrypted to get back the original plaintext message. Hence a cryptosystem is a collection of algorithms and associated procedures for hiding and revealing information. In symmetric key cryptography, same key is shared, i.e. the one key is used in both encryption and decryption, hence also known as single key or secret key encryption.
Symmetric key cryptography algorithms are simple requiring lesser execution time. As a consequence, these are commonly used for long messages. There are two types of symmetric key encryption modes one as block ciphers and other as stream ciphers. Block ciphers operate on groups of bits called blocks and each block is processed multiple number of times. The key applied in each round is in a unique manner. A stream cipher operates on one bit at a time i.e. The data is divided as small as single bits and then the encryption is done. In symmetric key encryption the AES algorithm and the DES algorithm different factors are analyzed.
ADVANCED ENCRYPTION STANDARD (AES) ALGORITHM
AES is a symmetric key algorithm which operates on two dimensional arrays of bytes known as state and the state consists of four rows of each bytes. AES has key size of 128,192 OR 256 Bits which protect against certain current and future attacks. Hardware and software both implementation are faster and can be implemented on various platforms.
DATA ENCRYPTION STANDARD (DES) ALGORITHM
DES is a symmetric block cipher having 64-bits long input key but uses only 56-bits in length. The decryption is performed by same password as encryption only the stages are carried out in reversed manner.DES has 16 rounds so to produce cipher text the main algorithm is repeated 16 times. Des is more vulnerable to brute force attack because as the number of round increases the algorithm of security exponentially increases.
