2001-02-19

Steak as Hash Function

Steak may be used as a hash function, and is in fact within it's own key setup scheme. The proposed Steak Hash Scheme consists of the following steps: Fill V and A with any value, AA  hexadecimal is proposed as a default, and set the S-boxes at will, with the identity mappings proposed as a default. Use Steak with this key data setup to encrypt the document. Discard the cipher text from this part of the operation. Then encrypt a pre-defined string. The resulting cipher-text is the hash value.

This Hash Scheme is epistemically one-way in the sense that you cannot practically and efficiently construct a hash table to map hash values to hashed documents. If you change one bit of the hashed document, then for any bit in the hash value there is an equally distributed probability that it will change. Retrieving any hashed document from a hash value will be exactly as hard as retrieving all (unknown) plain text encrypted prior to some portion of known plain text.