Patent ID: 9692592
Date: 2017-06-27
CPC Classifications: H04L

Claim:
1. A computer implemented method for preventing an attacker from extracting keys of an iterated block cipher performed on a computing device, the block cipher comprising a subkey for each of a plurality of iterations comprising an initial iteration, a plurality of middle iterations, and a final iteration, the method comprising: at the computing device, receiving and storing in a cipher state matrix, an encrypted message comprising content for a digital rights management (DRM) application, the encrypted message comprising a plurality of words, each word comprising a plurality of bytes, the cipher state matrix comprising a plurality of rows and a plurality of columns, each column storing a word of the message, each row storing a byte of each of the plurality of words of the message; and at the computing device where the attacker has control over an execution process of the iterated block cipher, performing the iterated block cipher by: