Strict key avalanche criterion.
Ed Dawson, Helen Gustafson, Anthony N. Pettitt · 1992
A block cipher, such as the DES cipher, is used to encrypt binary plaintext in discrete blocks of length n using a key of length m, to form ciphertext blocks of length n. A block cipher is said to satisfy the strict key avalanche criterion if a one bit change in the key causes on the average one half of the ciphertext bit positions to change. In this paper the importance of the strict key avalanche criterion for assessing the strength of a block cipher is highlighted. Statistical based methods for determining whether a block cipher satisfies the strict key avalanche criterion are given. 1.