Apparatus and Method for Stripping Parity Bits from an Input Stream

Patent Number 6801625
Issue Date 2004 10 05
Assignee Intel Corporation
Inventor(s) Dealy, Sheldon R.
State/Country OR

Title: Apparatus and method for stripping parity bits from an input stream

Abstract: The disclosed parity stripping technique quickly and efficiently converts a multi-byte input stream having parity bits to an output data stream that contains the same data as the input stream but without the parity bits. The multi-byte input stream is indexed according to the number of times a loop is completed. During each iteration of the loop, a portion of the input steam having an associated parity bit, such as a byte of the input stream, has its parity bit set to zero and the portion of the input key is then shifted a number of bits equal to the number of times the loop has been completed. The shifted value is then logically ORed with the portion of the memory used to hold the output data stream. Exmp. Claim 7 Ex Claim text A computer system comprising: a cryptographic engine, the cryptographic engine to encrypt and decrypt information based on an encryption key; a processor coupled to the cryptographic engine; a memory to store instructions that are executed by the processor, the instructions, when executed, causing the processor to convert an input encryption key including parity bits to an output encryption key that does not include parity bits by performing the tasks of (a) setting a parity bit of each portion of a plurality of portions of the input encryption key to zero to obtain a zeroed value; (b) shifting the bits in the zeroed value a certain number of bits based on a position of each portion in the input encryption key; and (c) integrating the shifted bits into a memory location that stores the output encryption key.