APPARATUS AND METHOD FOR BLOCK CIPHER PROCESS FOR INSECURE ENVIRONMENTS

摘要

Method and apparatus for increasing security of a cryptographic algorithm such as deciphering, enciphering, or a digital signature using a block type cipher such as AES implemented for instance in a "whitebox" model with the cipher key either known or unknown at the compilation time. This method is secure for use in entrusted environments, particularly for securing cryptographic keys. The look up tables characteristic of such algorithms are protected against attack here by making all such tables of the same size and indistinguishable, and further by masking the output values of such tables, typically where the tables carry out a permutation function or a logical exclusive OR operation.