A technique used to increase the security of block ciphers. It consists of steps that combine the data with portions of the key (most commonly using…

Whitening

https://en.wikipedia.org/wiki/Key_whitening

In cryptography, key whitening is a technique intended to increase the security of an iterated block

cipher. It consists of steps that combine the data with portions of the key.

The most common form of key whitening is xor-encrypt-xor -- using a simple XOR before the first

round and after the last round of encryption.

The first block cipher to use a form of key whitening is DES-X, which simply uses two extra 64-bit keys

for whitening, beyond the normal 56-bit key of DES. This is intended to increase the complexity of a

brute force attack, increasing the effective size of the key without major changes in the algorithm.

DES-X's inventor, Ron Rivest, named the technique whitening.

Incorrect answers:

Key Clustering - different encryption keys generated the same ciphertext from the same plaintext

message.

Key Schedule - an algorithm for the key that calculates the subkeys for each round that the

encryption goes through.

Key Exchange - a method in cryptography by which cryptographic keys are exchanged between two

parties, allowing use of a cryptographic algorithm.