sha-256 computed entirely by the typescript type checker. zero runtime.
import type { SHA256 } from "./sha256"; type Hash = SHA256<"Input string">; // ^? "da408360ba4fd661aaaacb205dd680fc71280558627f45f99dd2b5f578cbb506"
the type-level program faithfully implements fips 180-4: bits live in 32-tuples of 0 | 1, a ripple-carry adder does mod-2³² addition, the message schedule and 64-round compression run as tail-recursive conditional types. running tsc --noEmit is the hash.
install
use it
drop sha256.ts into your project and import SHA256<S>. that's the whole api.
import type { SHA256 } from "./sha256"; type A = SHA256<"">; // "e3b0c442..." type B = SHA256<"abc">; // "ba7816bf..."
input is a printable-ascii string literal. output is a 64-char lowercase hex string literal. unsupported characters resolve to never.
run the tests
the test vectors are compile-time Assert<Equals<...>> declarations. if tsc exits clean, they passed.
NODE_OPTIONS="--max-old-space-size=12288" pnpm exec tsc --noEmit
the big heap reservation is required — the checker allocates a lot of intermediate tuple types.
limits
- printable ascii + a few control chars. non-ascii →
never. - single 512-bit block (≤ 55 bytes) is what i actually tested. longer inputs are implemented but will probably exhaust the type checker.
- expect ~20s per hash on a modern laptop.