agentfootprint/dist/lib/sha256.js

The explainable agent framework — backtrack a wrong answer to the exact context that caused it (evidence, not guesses). Built on footprintjs.

"use strict";
/**
 * sha256Hex — FIPS 180-4 SHA-256 over a JS string, with no platform edge.
 *
 * Role:  Fold. A leaf function. It reads nothing, writes nothing and emits
 *        nothing; the receipt calls it to fingerprint content it must not
 *        keep.
 * Reads: its argument.
 * Emits: N/A.
 *
 * WHY NOT `rag/hash.ts` · `sha256`. That one reaches `node:crypto` through
 * `lazyRequire`, which is right where it lives: indexing a corpus is a Node
 * job that runs once, off any hot path. This one is called on EVERY LLM call,
 * including from an agent running in a browser through the `browser*`
 * providers — a `node:crypto` edge there would throw at request assembly and
 * take the run with it. `crypto.subtle.digest` is the browser answer and it is
 * asynchronous, which request assembly is not.
 *
 * So the algorithm is here, in about seventy lines, and
 * `test/time-travel/receipt-conformance.test.ts` checks it against
 * `node:crypto` on every input the suite hashes. A vendored primitive that is
 * never compared against the reference is a second truth waiting to happen.
 */
Object.defineProperty(exports, "__esModule", { value: true });
exports.sha256Hex = void 0;
/** Round constants — the first 32 bits of the fractional parts of the cube
 *  roots of the first 64 primes (FIPS 180-4 §4.2.2). */
const K = new Uint32Array([
    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
    0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
    0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
    0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
    0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
    0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
    0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
    0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2,
]);
function rotr(x, n) {
    return ((x >>> n) | (x << (32 - n))) >>> 0;
}
/** Hex SHA-256 of a string's UTF-8 bytes. 64 lowercase hex characters. */
function sha256Hex(input) {
    const message = new TextEncoder().encode(input);
    const bitLength = message.length * 8;
    // One 0x80 byte, then zeroes, then the 64-bit big-endian length: pad to the
    // next whole 64-byte block that leaves room for all nine of those bytes.
    const padded = ((message.length + 9 + 63) >> 6) << 6;
    const buffer = new Uint8Array(padded);
    buffer.set(message);
    buffer[message.length] = 0x80;
    const view = new DataView(buffer.buffer);
    view.setUint32(padded - 8, Math.floor(bitLength / 0x100000000));
    view.setUint32(padded - 4, bitLength >>> 0);
    const h = new Uint32Array([
        0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19,
    ]);
    const w = new Uint32Array(64);
    for (let offset = 0; offset < padded; offset += 64) {
        for (let i = 0; i < 16; i++)
            w[i] = view.getUint32(offset + i * 4);
        for (let i = 16; i < 64; i++) {
            const a = w[i - 15];
            const b = w[i - 2];
            const s0 = (rotr(a, 7) ^ rotr(a, 18) ^ (a >>> 3)) >>> 0;
            const s1 = (rotr(b, 17) ^ rotr(b, 19) ^ (b >>> 10)) >>> 0;
            w[i] = (w[i - 16] + s0 + w[i - 7] + s1) >>> 0;
        }
        let a = h[0];
        let b = h[1];
        let c = h[2];
        let d = h[3];
        let e = h[4];
        let f = h[5];
        let g = h[6];
        let hh = h[7];
        for (let i = 0; i < 64; i++) {
            const s1 = (rotr(e, 6) ^ rotr(e, 11) ^ rotr(e, 25)) >>> 0;
            const ch = ((e & f) ^ (~e & g)) >>> 0;
            const t1 = (hh + s1 + ch + K[i] + w[i]) >>> 0;
            const s0 = (rotr(a, 2) ^ rotr(a, 13) ^ rotr(a, 22)) >>> 0;
            const maj = ((a & b) ^ (a & c) ^ (b & c)) >>> 0;
            const t2 = (s0 + maj) >>> 0;
            hh = g;
            g = f;
            f = e;
            e = (d + t1) >>> 0;
            d = c;
            c = b;
            b = a;
            a = (t1 + t2) >>> 0;
        }
        h[0] = (h[0] + a) >>> 0;
        h[1] = (h[1] + b) >>> 0;
        h[2] = (h[2] + c) >>> 0;
        h[3] = (h[3] + d) >>> 0;
        h[4] = (h[4] + e) >>> 0;
        h[5] = (h[5] + f) >>> 0;
        h[6] = (h[6] + g) >>> 0;
        h[7] = (h[7] + hh) >>> 0;
    }
    let out = '';
    for (const word of h)
        out += word.toString(16).padStart(8, '0');
    return out;
}
exports.sha256Hex = sha256Hex;
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