US Patent 7649990 Apparatus to implement dual hash algorithm

An apparatus arranged to accept digital data as an input and to process the data according to one of either the Secure Hash Algorithm (SHA-1) or Message Digest (MD5) algorithm to produce a fixed length output word. The apparatus includes a plurality of rotational registers for storing data, one of the registers arranged to receive the input data, and data stores for initialization of some of the plurality of registers according to whether the SHA-1 or MD5 algorithm is used. The data stores include fixed data relating to SHA-1 and MD5 operation. Also included is a plurality of dedicated combinatorial logic circuits arranged to perform logic operations on data stored in selected ones of the plurality of registers.