Patent ID: 8582765
Filing Date: 2013-11-12
Classification: H04L

Abstract:
1. A method of ciphering or deciphering, by an integrated circuit, of data with a key by using at least one variable stored in a storage element and updated by successive operations, wherein: the at least one variable loaded with the data is masked by at least one first random mask applied before use of the key; the at least one masked variable is unmasked by at least one second mask applied after use of the key; the at least one first random mask is generated by at least one hardware processor using a first plurality of random quantities, the first plurality of random quantities comprising portions of the at least one first mask that are successively applied, in a first order, to the at least one variable for masking the at least one variable; the at least one second mask comprises a second plurality of random quantities comprising portions of the at least one second mask that are successively applied, in a second order that is different from the first random order, to the at least one masked variable for unmasking the at least one masked variable; the first plurality of portions random quantities of the at least one first random mask, when combined, represent the at least one second mask; and the second plurality of random quantities of the at least one second mask, when combined, represent the at least one first random mask.