SHACAL

SHACAL -1 and SHACAL -2 are symmetric block cipher with a variable key length of 128 bits to 512 bits based on the hash algorithms SHA family. The SHACAL algorithms have been designed by Helena glove and David Naccache, both employees of the smart card manufacturer Gemplus.

SHACAL -1 ( originally only SHACAL ) is a 160-bit block cipher based on the hash functions SHA-1. SHACAL -2 is a 256 -bit block cipher based on the hash functions SHA -256. Based on the respective Hashing the key is the message and the text to be encrypted replaces the initialization of the hash function. In order to present the function for decryption reversible, while obviating the final step of the addition, which ensures the fixed length of the hash value.

The recommended minimum length of the key is 128 bits, the maximum length is 512 bits. The use of keys with fewer than 512 bits, the missing points are filled with zeros so that the length of 512 bits is obtained.

Shacal - 2 2003 was selected by the NESSIE project as one of its 17 recommended algorithms.