Patent ID: 8966279
Filing Date: 2015-02-24
Classification: H04L

Abstract:
1. A method for applying a cryptographic process to a message using at least one key, the method comprising: expanding a key for the cryptographic process into a plurality of new keys using a first expansion function, each new key associated with a different round of the cryptographic process; prior to using a particular one of the new keys for an associated particular round of the cryptographic process, applying a second expansion function to the particular new key that uniquely maps each bit of the particular new key to a different location in an expanded new key in a different order, wherein the expanded new key includes additional bits between the mapped bits; applying the particular round of the cryptographic process to a portion of the message using the expanded new key to produce an expanded result; and recovering an encrypted version of the message portion from the expanded result using a recovery function, wherein the recovery function recovers only bits from the expanded result that have been subject to a cryptographic operation involving the mapped bits from the expanded new key.