sha2

SHA-256 for ris with the processor's SHA instructions: RustCrypto sha2 0.10.9's x86_64 backend, ported. On an x86_64 processor with SHA-NI it hashes about 2 GB/s on one core, as OpenSSL does; elsewhere it uses the software rounds.

require github.com/domify/sha2 v0.1.0 as sha2

import sha2/sha2/sha256::{Sha256}

Sha256.hexdigest("abc") # => "ba7816bf..."

digest = Sha256.new
digest.update(part) # a Str or a String, as often as the data arrives
digest.hexfinal     # or `final`: the 32 bytes, or `hexfinal(w)` onto a
                    # Str::Builder

Sha256 is a struct: a digest is a value on the stack, and hashing allocates nothing. It is copied when passed, so update answers Nil rather than a copy to chain on: keep a digest in a variable or a field.

The digests are FIPS 180-4's, the same as std/digest's SHA256.

Speed

A 416,074-byte page, one core of a Ryzen 7 PRO 6850U, --release:

	Per page
std/digest SHA256	1.12 ms
Sha256 (SHA-NI)	0.21 ms

How it works

• sha2/sha256.ri: the asm block is x86.rs's digest_blocks, one instruction per intrinsic, written by tools/gen_asm.py. cpuid is asked once for SHA-NI, SSSE3 and SSE4.1.
• A Str is read as the tape allows: whole blocks eight bytes a load into a one-block buffer in the digest, hashed from there.
• The module is @[Ffi], as the asm takes pointers; the API has none.

Checks

./check.sh

sha2/sha256_test.ri holds both paths to std/digest's SHA256: every length to 2,100 bytes, whole and in uneven pieces, and 1 MB.