Key Whitening

Key Whitening - often only Whitening - is a cryptographic technique by which the security of iterated block ciphers is increased. If you encrypt a plaintext block with Whitening is before the first round of the key associated with parts (pre- whitening ); XOR is used mostly here. Some ciphers use whitening also also after the last round (post - whitening ).

The whitening is mainly used in Feistelchiffren to obscure structures of the clear text and entering the last round and so to increase the complexity of an attack.

Examples of ciphers with whitening are RC5, RC6, MARS, Twofish, and Rijndael.

• Symmetric Cryptosystem