Encryption of pseudorandom number generator logic circuits

Abstract

The paper presents obfuscation methods for logic circuits of pseudorandom number generators (PRNG) on shift registers with linear and nonlinear feedback, which are based on the PRNG additional logic elements for protection against reverse engineering. The encryption of the PRNG logic circuit changes its design in the way that the device works correctly only if the signals at the additional key inputs of the PRNG take correct values. Even with a small bit capacity of PRNG, a huge number of PRNG implementations with a different number of states and different properties can be provided. The concept of (М + 1)-sequence generator is introduced. The possibility of transforming generators of (M – 1)-sequence and (M – 3)-sequence into generators of (M + 1)-sequence is demonstrated.