Patent ID: 9143317
Filing Date: 2015-09-22
Classification: H04L

Abstract:
1. A computer implemented method of performing an iterated block cipher having resistance to cipher key reverse engineering, the method comprising: generating an iteration specific cipher subkey for multiple iterations of the iterated block cipher; using one or more processors, rotating columns of a memory buffer corresponding to a cipher state matrix, the memory buffer rotated according to a first rotation index; performing a first rotation of the columns of a first iteration specific cipher subkey according to the first rotation index; performing an iteration of block cipher operations on the memory buffer corresponding to the cipher state matrix; rotating the columns of the cipher state matrix in the corresponding memory buffer according to a second rotation index and an inverse of the first rotation index using a rotation to an intermediate rotation index; rotating the columns of the iteration specific cipher subkey to the second rotation index without reversing the first rotation of the subkey; and generating an output cipher block from the cipher state matrix.