Explanation of Blowfish

Question

Give a brief explanation of the term Blowfish.

Answer 1

Blowfish is the 64-bit block cipher which is developed by Schneier. It is the Feistel cipher and each round comprises a key-dependent permutation and the key-and-data-dependent substitution. All operations are based upon exclusive-ors and additions on 32-bit words. The key has the variable length (with a maximum length of the 448 bits) and is employed to generate various subkey arrays. This cipher was intended specifically for the 32-bit machines and is appreciably faster than DES. There was an open competition for the cryptanalysis of the Blowfish supported through Dr. Dobb's Journal with the $1000 prize. This contest ended in April 1995 and among results were the discoveries of continuation of convinced weak keys, the attack against three-round version of the Blowfish, and the differential attack against convinced variants of Blowfish. But, Blowfish can still be considered secure, and Schneier has invited cryptanalysts to carry on investigating his cipher.