Patent ID: 7848515
Filing Date: 2010-12-07
Classification: H04L

Abstract:
1. An encryption protection method, comprising: constructing a masking table having a plurality of masks, including a true mask; applying all masks of the masking table to a cipher key to generate masked keys, including one true key and a plurality of dummy keys, for use in multiple loops of a cipher algorithm; executing the multiple loops of the cipher algorithm upon input message data to obtain processed message data results, each loop of the cipher algorithm being executed using a different one of the masked keys until all masked keys have been used once, the executing of a loop of the cipher algorithm using the true key producing a true message data result, while the executing of a loop of the cipher algorithm using any of the dummy keys producing a dummy message data result: and storing the true message data result in a first memory location and storing the dummy message data results in one or more second memory locations, wherein the execution of the loops using the dummy keys and the storage of the dummy message data results are to inhibit cryptoanalysis attacks by masking operations that use the true key, and wherein in executing a loop of the cipher algorithm, a set of round subkeys is generated from the masked key used for that loop of the cipher algorithm, the true key generating a set of true round subkeys to be applied to the message data in rounds of one loop of the cipher algorithm to produce the true message data result, the plurality of dummy keys generating corresponding sets of dummy round subkeys to be applied to the message data in rounds of respective loops of the cipher algorithm to produce the dummy message data results.