MD5 Crypt is a cryptographic algorithm used commonly in UNIX system for authentication. By using the additional randomization of the salt and complexity of the scheme, it makes the traditional password cracking techniques invalid on common computing systems and the security of the system is guaranteed. Benefited from the thriving of petaflops heterogeneous supercomputer system recently, such as Tianhe1A, the security of MD5 Crypt is facing a threat of Brute Force Attack again. Many works have been done on the GPUaccelerated platform to improve the performance of MD5 Crypt. However, little increase has been achieved by using the constant memory of CUDA architecture. This paper explores this problem and archived 44.6% improvement by allocating constant memory to the padding array. And this paper presents a high scalable implementation of Brute Force Attack Algorithm of MD5 Crypt on Tianhe-1A, which is the fastest heterogeneous supercomputer of the world. The experimental results have shown that 326 thousands MD5 hashes could be checked per second on one single computing node and outperform 5.7X than the CPU version. On multi -nodes, the implementation also shows a great scalability. Consequently, it issued a new challenge to the security of MD5 crypt for authentication.
