Approxhash: delay, power and area optimized approximate hash functions for cryptography applications.

Rapid evolution of E-world demands delay, power and area optimized digital circuits/systems while still meeting the security requirements of the cryptography applications. Cryptographic hash functions (which are considered the workhorse of security layers) provide compressive and non-invertible outputs. This signifies that approximate implementation of cryptographic hash functions can provide improvements in delay, power and area without considerable change in security level. In this paper, we first examine likelihood of infusing approximation in cryptographic hash functions and then propose a methodology to evaluate the effects of approximation. Further, we demonstrate four approximate pipelined implementations of Secure Hash Algorithm I (SHA-1). Our simulation results show that the proposed approximate pipelined SHA-is provide significant improvements in delay, power and area with negligible change in security level.