Explanation of Feistel Cipher

Question

Give a brief explanation of Feistel Cipher.

Answer 1

Feistel ciphers are special class of the iterated block ciphers where cipher-text is computed from the plaintext by repeated application of same transformation or round function. Feistel ciphers are as well sometimes called DES-like ciphers.

In the Feistel cipher, the text being encrypted is dividing in two halves. The round function f is applied to one half using the subkey and the output of are exclusive-ored with other half. The two bisects are then swapped. Each round follows the same pattern apart from for last round where there is no swap.