Patent ID: 7668310
Filing Date: 2010-02-23
Classification: G06F,H04L

Abstract:
1. A method for performing a cryptographic operation with resistance to external monitoring attacks, where said cryptographic operation includes performing a substitution operation using a predefined substitution table, said method comprising: (a) obtaining a representation of a predefined substitution table specifying a corresponding table value for each of a plurality of possible table index values; (b) using random information, transforming said representation of said predefined substitution table into a new randomized representation of said substitution table; (c) receiving a datum to be cryptographically processed; (d) computing a blinded representation of a table index value from at least said datum; (e) using said new randomized representation of said table, performing a substitution on said blinded table index value to derive a blinded representation of the table value corresponding to an unblinded version of said table index value in step (d); and (f) using said blinded table value to compute a cryptographic result for use in securing a cryptographic protocol.