SRAM-based unique chip identifier techniques

Integrated circuit (IC) identification using unclonable digital fingerprints facilitates the authentication of ICs, device tracking, and cryptographic functions. In this paper, we present two hardware methods exploiting the inherent process-induced mismatch of SRAM cells. The proposed circuits improve upon those previously published by reducing the number of bits that vary from trial to trial, and can be used at times other than just IC power-up. The proposed circuits and methods are compared with the previous power-up approach using the experimental results from a 90-nm test chip. The required SRAM array periphery circuit changes allow the use of standard foundry SRAM cells and do not impact the memory access time.