We have used the Ilia Levin implementation of sha256 to create our own HMAC-SHA256 algorithm used for computing the DetNetAuth header.
This repo contains under hmac-sha256 directory an implementation of the HMAC SHA-256 secure hash algorithm defined in FIPS 198-1
This implementation supports clang (recommended).
Other compilers may also work with some minor code tweaking.
cd hmac-sha256
Use make or sh hmac-sha256.c -c -o hmac-sha256.o to compile into an object file
that you may link with your project later.
Use make basic_test or sh hmac-sha256.c -DSHA256_SELF_TEST__ to compile an
executable binary that will perform a basic test for HMAC-256.
HMAC("abc", "123") = 8f16771f9f8851b26f4d46fa17de93e2711c7e51337cb8a608af81e1c1b6ae
Use make performance_test or sh hmac-sha256.c -DSHA256_PERF_TEST__ to compile an
executable binary that can be used to benchmark our HMAC implementation for different
input sizes (packet vs headers only)