Patent ID: 6640305
Filing Date: 2003-10-28
Classification: G06F,G06Q,H04L

Abstract:
A method for processing a cryptographic secret distributed to a plurality of tamper-resistant devices among a group of devices sharing a group secret but having individually-assigned group offsets, said method comprising the steps of:(a) at a recipient device within said group, receiving an input value from a party that knows said group secret; (b) combining at least a portion of said input value, by using at least said individually-assigned group offset corresponding to said recipient device, to produce a group verification result; (c) if said verification result indicates that said recipient device is contained in said plurality of devices: (i) retrieving said group secret from a memory; (ii) deriving said cryptographic secret by performing a cryptographic operation combining said group verification result, said group secret, and at least a portion of said input value; (iii) deriving a final result by using said cryptographic secret in at least one subsequent cryptographic operation; (iv) returning said final result; and (d) if said verification result indicates that said recipient device is not contained in said plurality of devices, returning only information that is not usable to derive said final result.