What is Feistel Cipher

Question

What is Feistel Cipher? briefly explain it.

Answer 1

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

In Feistel cipher, the text being encrypted is divided into two halves. The round function f is exerted to one half by employing a subkey and the output of f is exclusive with the other half. The two halves are then swapped with each other. Each and every round obeys similar pattern apart from for the final round where there is no swap.