An efficient implementation of PBKDF2 with RIPEMD-160 on multiple FPGAs

A weakness of many security systems is the strength of the chosen password or key derivation function. We show how FPGA technology can be used to effectively attack cryptographic applications with a password dictionary. We have implemented two independent PBKDF2 cores each using four HMAC cores with pipelines calculating a RIPEMD-160 hash to derive encryption keys together with one resource optimized AES-256 XTS core for direct decryption on a Xilinx Spartan6-LX150 FPGA. Our design targets TRUECRYPT containers, but may be applied to similar encryption tools with little adaption. In order to save resources and maximize speed, we have further optimized the RIPEMD-160 hash function for this purpose. Our design executed on the multi-FPGA system RIVYERA S6-LX150 containing 128 S6-LX150 FPGAs, finally reaches a peak performance of about 245,000 passwords per second.