feat(stdlib): Crypto.* — SHA-256 + HMAC-SHA256, constant-time verify (#19)
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The security-sensitive counterpart to the fast, non-cryptographic Hash.*
library: standard, test-vector-backed hashing for signed saves and message
integrity, kept in its own namespace so nobody reaches for the wrong tool.

  Crypto.sha256(s)                SHA-256 -> 64-char lowercase hex
  Crypto.hmac_sha256(key, msg)    HMAC-SHA256 -> 64-char hex
  Crypto.verify_hmac(key, msg, mac)  recompute + constant-time compare -> bool
  Crypto.hex(s)                   lowercase hex of a string's bytes
  Crypto.ct_equal(a, b)           constant-time string equality

The primitives are implemented from scratch in plain integer LLVM IR
(FIPS 180-4 / RFC 2104): no libc crypto, no data-dependent branches in the
compression rounds, so a given input hashes to the same 32 bytes on every
platform and run. Digests are returned as hex strings, not raw bytes, because
a `str` is null-terminated and a raw digest can contain a NUL. MAC checks use
a non-short-circuiting compare so timing does not leak how much of a forged tag
was correct.

Emitted on demand via g_uses_cryptort, mirroring the emit_hash prelude gate.
Scoped to the deterministic, known-answer-testable core; OS-backed
random_bytes (the one piece that can't be validated by test vectors) is left
for a follow-up.

Tested against published SHA-256 vectors (empty/"abc"/fox + 55/56/64-byte
multi-block padding) and HMAC-SHA256 vectors; wired into the self-host suite as
`crypto`. Docs: a new Crypto section with honest "what this protects / does
not" guidance, one page per method, all fences checked and in the inventory.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
Orkun ÇAKILKAYA 2026-08-30 13:37:02 +03:00
parent 1858ab65ad
commit 9ae69e64b4
15 changed files with 11536 additions and 10437 deletions

View file

@ -409,5 +409,12 @@
"clock-set",
"clock-advance",
"clock-reset"
],
"crypto": [
"crypto-sha256",
"crypto-hmac_sha256",
"crypto-verify_hmac",
"crypto-hex",
"crypto-ct_equal"
]
}

View file

@ -28,6 +28,7 @@ function selfhost_frags() -> []pointer {
push(f, "selfhost/emit_vector.ludic")
push(f, "selfhost/emit_text.ludic")
push(f, "selfhost/emit_hash.ludic")
push(f, "selfhost/emit_crypto.ludic")
push(f, "selfhost/emit_list.ludic")
push(f, "selfhost/emit_ease.ludic")
push(f, "selfhost/emit_collide.ludic")

View file

@ -52,6 +52,7 @@ function cmd_selfhost_test() -> int {
sh_case("datetime2", "2026-08-30 07:05:09 30/08/26 0 -1 3600 5400 30 0")
sh_case("textsplit", "1 1 1 3 1 1 1 1 1 1 1")
sh_case("hash", "-2128831035 -468965076 114400290 114400290 0 -873187034 1095738169 0 1364076727 -2114883783 -845898438 -845898438 -78065325 -78057399 -3750763034362895579 -5808556873153909620 -4100651535478758590 -4100651535478758590 0 -5451962507482445012 7256831767414464289")
sh_case("crypto", "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad d7a8fbb307d7809469ca9abcb0082e4f8d5651e46d3cdb762d02d0bf37c9e592 9f4390f8d30c2dd92ec9f095b65e2b9ae9b0a925a5258e241c9f1e910f734318 b35439a4ac6f0948b6d6f9e3c6af0f5f590ce20f1bde7090ef7970686ec6738a ffe054fe7ae0cb6dc65c3af9b61d5209f439851db43d0ba5997337df154668eb f7bc83f430538424b13298e6aa6fb143ef4d59a14946175997479dbc2d1a3cd8 5bdcc146bf60754e6a042426089575c75a003f089d2739839dec58b964ec3843 1 0 0 1 0 0 616263")
sh_case("long", "1000000000000 1000000000001 1000000000005 3000000000000 1 1 1 -1000000000000 1000000 13")
sh_case("color", "16744512 1090486336 1090486336 8355711 8355711 8355711")