RunFein: a rapid prototyping framework for Feistel and SPN-based block ciphers

Block ciphers are the most prominent symmetric-key cryptography kernels, serving as fundamental building blocks to many other cryptographic functions. This work presents RunFein, a tool for rapid prototyping of a major class of block ciphers, namely product ciphers (including Feistel network and Substitution permutation network-based block ciphers). RunFein accepts the algorithmic configuration of an existing/new block cipher from the user through a GUI to generate a customized software implementation. The user may choose from various micro-architectural templates (unrolled, pipelined, sub-pipelined) to generate an HDL description of the cipher. Various modes of operation and the NIST test suite may also be included. This high-level design approach eliminates the laborious and repetitive development efforts for VLSI realizations of block ciphers. It allows a quick design exploration, consequently enabling fast benchmarking in terms of critical resource estimation of various versions/configurations of a cipher that varies in terms of security, complexity and performance. Using RunFein, we have successfully implemented some well-known product ciphers and benchmarked their performance without significant degradation against their published hand-crafted implementations in literature.