COMPUTER FUNDAMENTALS

Detailed explanation-1: -Explanation: The DES Algorithm Cipher System consists of 16 rounds (iterations) each with a round key. Explanation: DES encrypts blocks of 64 bits using a 64 bit key. 4. In the DES algorithm, although the key size is 64 bits only 48bits are used for the encryption procedure, the rest are parity bits.

Detailed explanation-2: -DES is based on the Feistel block cipher, called LUCIFER, developed in 1971 by IBM cryptography researcher Horst Feistel. DES uses 16 rounds of the Feistel structure, using a different key for each round.

Detailed explanation-3: -Understanding Blowfish It consists of 16 Feistel-like iterations, where each iteration operates on a 64-bit block that’s split into two 32-bit words. Blowfish uses a single encryption key to both encrypt and decrypt data.

Detailed explanation-4: -DES with any number of rounds fewer than 16 could be broken with a known-plaintext attack more efficiently than by a brute-force attack. This explains the “Why not less than 16". As for the “why not more than 16", that is a tradeoff for speed of execution (more rounds = less speed).

Detailed explanation-5: -The Data Encryption Standard is a symmetric-key block Cipher based on Feistel structure. It uses 16 rounds of Feistel Structure. It was developed in the early 1970s and was approved as a federal standard in November 1976. It was reaffirmed as a standard in 1983, 1988 and again in 1999.