rsip_sha256_kat Directory Reference

Directory dependency graph for rsip_sha256_kat:

Directories
	src

Detailed Description

On-silicon FIPS 180-4 known-answer test for ra8_rsip_sha256. ra8_rot re-computes an image digest through this function, so its correctness is security-critical; the app hashes three published NIST vectors on the real M85 – the empty string, "abc", and a two-block message – and checks the digests.

The RSIP-E50D is not register-mapped

This was the first app ever to drive the RSIP hardware on a board, and what it found is the durable fact worth keeping. HUM Ch 52 "Renesas Secure IP (RSIP-E50D)" is a six-page feature overview (p 3302-3307) with no register interface at all; Renesas drives the engine through FSP's opaque procedural "primitive" command sequences. The register map that had been written into ra8_rsip.c was invented, and on silicon it behaved accordingly: the BIST self-test never passed, the hash returned k_ra8_err_hw_timeout with an all-zero digest because the HASH_STATUS poll never saw its bit assert, and a J-Link read of the RSIP window at 0x403B0000 found every register reading zero with none of the driver's writes sticking.

Nothing on the host could have caught it: the host tests all run RA8_OFF_TARGET, which takes the software fallback.

So ra8_rsip_sha256 computes the digest with the in-tree software SHA-256 (RA8_RSIP_SOFTWARE_BACKEND, enabled unconditionally). The invented hardware sequence is retained but never compiled, behind RA8_RSIP_HASH_HARDWARE, as a starting point for a future FSP-derived port. ra8_rot's on-silicon image digest works because of the software path, not despite it.