Power signature obfuscation by applying variable delay to signal propagation in data processing operation

摘要

A data processing apparatus is configured to perform a data processing operation on one or more data value(s) in response to a data processing instruction. The apparatus comprises a delay unit (30, 40, fig. 1A) situated on a path within the apparatus, wherein the delay unit is configured to apply a delay to propagation of a signal A, B, on the path and propagation of the signal forms part of the operation. The apparatus is configured to determine a result of the operation at a predetermined time point, wherein the predetermined time point follows initiation of the operation by a predetermined time interval. The delay unit is configured such that the time for the operation to be performed plus the delay is less than the predetermined time interval. The delay unit is configured such that the delay applied is changed for a subsequent performance of the operation on the data value(s) in response to the instruction. The signal path may be a data, control or clock path. There may be further delay units. In a typical application, the invention is used to resist power analysis attacks, e.g. differential or simple power analysis, by obfuscating the power signature of the apparatus.