This paper presents a Performance Analysis of CUDA and OpenCL. Three different cryptographic algorithms, i.e. DES, MD5, and SHA-1 have been selected as the benchmarks for extensive analysis of the performance gaps between the two.Our results show that, on the average scenario, CUDA performs 27% better than OpenCL while in the best case scenario it takes over OpenCL by 30%. As far as the optimal number of threads per block goes, 256 threads per block is the most performant choice,proving that the CUDA architecture is able to deal with an increased pressure on the register file without problems as CUDA scores 4.5 times over OpenCL in terms of stability
