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)