SHA-256 implementation to compliment a portable byte-oriented AES-256 implementation in C at http://www.literatecode.com/aes256

There is also a newer version in the mark2 directory. This version is cleaner and closer to a reference implementation. It no longer has built-in support features for endianness, but you may easily adapt the code to different endianness shall you need that.

Unlike the previous implementation, the Mark 2 one is formally verifiable with CBMC