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Common Encryption Algorithms| Category | | | Summary | | | Body | Common Encryption Algorithms
By: Cpt Rae
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The following article is a brief description of commonly used encryption algorithms. It only includes a brief description of the algorithms and is not a technical reference to them.
DES
DES stands for Data Encryption Standard and is a standardised encryption algorithm developed in 1976. DES is also referred to as DEA or Data Encryption Algorithm. The DES algorithm finds its roots in Horst Feistel's Lucifer cipher. DES is a block cipher, which means it works on a fixed block of plaintext and then converts it into ciphertext. The block size of DES is 64 bits. The key used in the algorithm is of 64 bits, but 8 of these is used for parity purposes, thus the effective key length becomes 56 bits. The basic structure of the algorithm is the Feistel Structure which involves swapping, permutations and XOR operations done over multiple rounds to increase security.
DES is not considered secure anymore. This is because due to increase in processing power and decrease in hardware costs, it is now possible to implement a successful bruteforce attack on DES. The primary reason for this is the key size (56 bits), which is relatively short compared to modern standards.
Triple DES
Triple DES is a high security block cipher derived from DES (Data Encryption Standard). Is was developed by Walter Tuchman at IBM, and was first published in 1978. Like DES, the block size here is 64 bits and it is based upon the Fiestel structure but its key size is 168 bits, which happens to be equal to three 56 bit keys used in DES. The three steps used in implementing Triple DES are DES encryption, followed by a DES decryption, followed by a DES encryption again.
IDEA
IDEA stands for the International Data Encryption Algorithm. It was developed by Xuejia Lai and James L. Massey in 1991. It was originally named Improved Proposed Encryption Standard (IPES) as it was meant as a replacement for DES. IDEA is also a block cipher like DES. Its block size is also 64 bits, but the key size here is 128 bits. The algorithm has been used in PGP Version 2.0 and is also an option in OpenPGP.
Blowfish
Blowfish is a symmetric block cipher designed in 1993. It was designed by Bruce Schiener as a replacement for DES. The developer has also stated that the algorithm will always remain free for use by anyone. The underlying structure of the algorithm is Fiestel structure, and it divides the plaintext into 64 bit blocks. The unique thing about the algorithm is that it has a variable key size ranging from 32 to 448 bits.
RC5
RC5 is a block symmetric key cipher designed in 1994 by Ron Rivest (of RSA Labs). The block size in RC5 varies. It can be 32, 64 or 128 bits. The key itself is of variable size, and can range upto 2040 bits. This algorithm is also based upon the Fiestel structure and has 12 rounds to make cryptanalysis difficult. RC6, one of the candidates of the AES challenge, was based upon RC5.
References :-
Applied Cryptography by Bruce Schiener
Cryptography and Network Security by William Stallings
Security in Computing by Pfleeger and Pfleeger
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Written by Rae (14 November 2005)
Cpt Rae is C/O of Knowledge Bank Tutorial Writing |
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This article was imported from the CyberArmy University site. (original author: rae)
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