Patent ID: 7257229
Filing Date: 2007-08-14
Classification: H04L

Abstract:
1. A key scheduler for at least one of 1) producing a new ciphering key by a key expansion process and 2) recovering a previous ciphering key by an inverse expansion process utilizing a round key value, the scheduler comprising: a set of adders, each adder receiving a first input comprising a portion of the round key value and a second input; transformation circuitry for producing reversible digital transformation of an input of the transformation circuitry, an output of the transformation circuitry provided to one of the adders as its second input; and a first set of arbitration devices, each of which selects between a first input comprising the portion of the round key value received by a particular one of the adders and a second input comprising an output of the particular one of the adders, wherein an output of one of the arbitration devices provides the input to the transformation circuitry, and an output of each remaining arbitration device provides the second input of one of the adders.