Patent ID: 7720225

Claim:
A computing device implemented method for executing a multiple split, masked substitution table cryptographic process comprising cryptographic steps based on a defined cryptographic process, the defined cryptographic process accepting an input, generating an output, and utilizing one or more originally-defined substitution tables; the cryptographic process accepting the input and generating a masked output equivalent to the output as masked by the mask value; the method comprising the steps of: defining a mask value, generating, for each of the one or more originally-defined substitution tables, a set of two or more split, masked substitution tables for that originally-defined substitution table by masking data word entries in that originally-defined substitution table with a corresponding at least one random value data word and masking a one of the corresponding at least one random value data word with the mask value to form split table entries, and distributing bits of the split table entries according to a pre-determined distribution arrangement to form entries in the set of two or more split, masked substitution tables, the set of two or more split, masked substitution tables being usable in place of that originally-defined substitution table and the mask value in the cryptographic process, executing on the input the cryptographic steps by inputting copies of the input into the generated sets of split, masked substitution tables to generate a set of split, masked substitution table outputs, and combining the set of split, masked substitution table outputs to obtain the masked output equivalent to the output as masked by the mask value.