MD5 Crypt is a cryptographic algorithm used commonly in UNIX system for authentication. Thanks to the additional randomization of the salt and complexity of the scheme, it makes the traditional password cracking techniques invalid on common computing systems so that the security of the system is guaranteed. As a result of the thriving of petaflops heterogeneous supercomputer system in recent decades, the security of MD5 Crypt is facing a threat of brute-force attack again. However, the complexity of heterogeneous programming and the sophistication of large-scale parallelism still hamper the password recovering. In this paper, we implemented brute-force attack of MD5 Crypt on Tianhe-1A，the world’s fastest supercomputer， by organizing the assignment between CPU and GPU reasonably and making several optimizations according to MD5 Crypt for GPU. Based on the experimental results, our algorithm achieves a great scalability. It checked more than 1.8 billion passwords in a second on the full system. Thus it issues a new challenge to the security of MD5 crypt for authentication.
Developing adaptive multi-device applications with the Heterogeneous Programming Library
