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* GHash from AES-GCM and its little-endian "mirror image" Polyval from AES-SIV.
*
* Implemented in terms of GHash with conversion function for keys
* GCM GHASH from
* [NIST SP800-38d](https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38d.pdf),
* SIV from
* [RFC 8452](https://datatracker.ietf.org/doc/html/rfc8452).
*
* GHASH modulo: x^128 + x^7 + x^2 + x + 1
* POLYVAL modulo: x^128 + x^127 + x^126 + x^121 + 1
*
* @module
*/
// prettier-ignore
import { abytes, aexists, aoutput, clean, copyBytes, createView, Hash, toBytes, u32, } from "./utils.js";
const BLOCK_SIZE = 16;
// TODO: rewrite
// temporary padding buffer
const ZEROS16 = /* @__PURE__ */ new Uint8Array(16);
const ZEROS32 = u32(ZEROS16);
const POLY = 0xe1; // v = 2*v % POLY
// v = 2*v % POLY
// NOTE: because x + x = 0 (add/sub is same), mul2(x) != x+x
// We can multiply any number using montgomery ladder and this function (works as double, add is simple xor)
const mul2 = (s0, s1, s2, s3) => {
const hiBit = s3 & 1;
return {
s3: (s2 << 31) | (s3 >>> 1),
s2: (s1 << 31) | (s2 >>> 1),
s1: (s0 << 31) | (s1 >>> 1),
s0: (s0 >>> 1) ^ ((POLY << 24) & -(hiBit & 1)), // reduce % poly
};
};
const swapLE = (n) => (((n >>> 0) & 0xff) << 24) |
(((n >>> 8) & 0xff) << 16) |
(((n >>> 16) & 0xff) << 8) |
((n >>> 24) & 0xff) |
0;
/**
* `mulX_POLYVAL(ByteReverse(H))` from spec
* @param k mutated in place
*/
export function _toGHASHKey(k) {
k.reverse();
const hiBit = k[15] & 1;
// k >>= 1
let carry = 0;
for (let i = 0; i < k.length; i++) {
const t = k[i];
k[i] = (t >>> 1) | carry;
carry = (t & 1) << 7;
}
k[0] ^= -hiBit & 0xe1; // if (hiBit) n ^= 0xe1000000000000000000000000000000;
return k;
}
const estimateWindow = (bytes) => {
if (bytes > 64 * 1024)
return 8;
if (bytes > 1024)
return 4;
return 2;
};
class GHASH {
// We select bits per window adaptively based on expectedLength
constructor(key, expectedLength) {
this.blockLen = BLOCK_SIZE;
this.outputLen = BLOCK_SIZE;
this.s0 = 0;
this.s1 = 0;
this.s2 = 0;
this.s3 = 0;
this.finished = false;
key = toBytes(key);
abytes(key, 16);
const kView = createView(key);
let k0 = kView.getUint32(0, false);
let k1 = kView.getUint32(4, false);
let k2 = kView.getUint32(8, false);
let k3 = kView.getUint32(12, false);
// generate table of doubled keys (half of montgomery ladder)
const doubles = [];
for (let i = 0; i < 128; i++) {
doubles.push({ s0: swapLE(k0), s1: swapLE(k1), s2: swapLE(k2), s3: swapLE(k3) });
({ s0: k0, s1: k1, s2: k2, s3: k3 } = mul2(k0, k1, k2, k3));
}
const W = estimateWindow(expectedLength || 1024);
if (![1, 2, 4, 8].includes(W))
throw new Error('ghash: invalid window size, expected 2, 4 or 8');
this.W = W;
const bits = 128; // always 128 bits;
const windows = bits / W;
const windowSize = (this.windowSize = 2 ** W);
const items = [];
// Create precompute table for window of W bits
for (let w = 0; w < windows; w++) {
// truth table: 00, 01, 10, 11
for (let byte = 0; byte < windowSize; byte++) {
// prettier-ignore
let s0 = 0, s1 = 0, s2 = 0, s3 = 0;
for (let j = 0; j < W; j++) {
const bit = (byte >>> (W - j - 1)) & 1;
if (!bit)
continue;
const { s0: d0, s1: d1, s2: d2, s3: d3 } = doubles[W * w + j];
(s0 ^= d0), (s1 ^= d1), (s2 ^= d2), (s3 ^= d3);
}
items.push({ s0, s1, s2, s3 });
}
}
this.t = items;
}
_updateBlock(s0, s1, s2, s3) {
(s0 ^= this.s0), (s1 ^= this.s1), (s2 ^= this.s2), (s3 ^= this.s3);
const { W, t, windowSize } = this;
// prettier-ignore
let o0 = 0, o1 = 0, o2 = 0, o3 = 0;
const mask = (1 << W) - 1; // 2**W will kill performance.
let w = 0;
for (const num of [s0, s1, s2, s3]) {
for (let bytePos = 0; bytePos < 4; bytePos++) {
const byte = (num >>> (8 * bytePos)) & 0xff;
for (let bitPos = 8 / W - 1; bitPos >= 0; bitPos--) {
const bit = (byte >>> (W * bitPos)) & mask;
const { s0: e0, s1: e1, s2: e2, s3: e3 } = t[w * windowSize + bit];
(o0 ^= e0), (o1 ^= e1), (o2 ^= e2), (o3 ^= e3);
w += 1;
}
}
}
this.s0 = o0;
this.s1 = o1;
this.s2 = o2;
this.s3 = o3;
}
update(data) {
aexists(this);
data = toBytes(data);
abytes(data);
const b32 = u32(data);
const blocks = Math.floor(data.length / BLOCK_SIZE);
const left = data.length % BLOCK_SIZE;
for (let i = 0; i < blocks; i++) {
this._updateBlock(b32[i * 4 + 0], b32[i * 4 + 1], b32[i * 4 + 2], b32[i * 4 + 3]);
}
if (left) {
ZEROS16.set(data.subarray(blocks * BLOCK_SIZE));
this._updateBlock(ZEROS32[0], ZEROS32[1], ZEROS32[2], ZEROS32[3]);
clean(ZEROS32); // clean tmp buffer
}
return this;
}
destroy() {
const { t } = this;
// clean precompute table
for (const elm of t) {
(elm.s0 = 0), (elm.s1 = 0), (elm.s2 = 0), (elm.s3 = 0);
}
}
digestInto(out) {
aexists(this);
aoutput(out, this);
this.finished = true;
const { s0, s1, s2, s3 } = this;
const o32 = u32(out);
o32[0] = s0;
o32[1] = s1;
o32[2] = s2;
o32[3] = s3;
return out;
}
digest() {
const res = new Uint8Array(BLOCK_SIZE);
this.digestInto(res);
this.destroy();
return res;
}
}
class Polyval extends GHASH {
constructor(key, expectedLength) {
key = toBytes(key);
abytes(key);
const ghKey = _toGHASHKey(copyBytes(key));
super(ghKey, expectedLength);
clean(ghKey);
}
update(data) {
data = toBytes(data);
aexists(this);
const b32 = u32(data);
const left = data.length % BLOCK_SIZE;
const blocks = Math.floor(data.length / BLOCK_SIZE);
for (let i = 0; i < blocks; i++) {
this._updateBlock(swapLE(b32[i * 4 + 3]), swapLE(b32[i * 4 + 2]), swapLE(b32[i * 4 + 1]), swapLE(b32[i * 4 + 0]));
}
if (left) {
ZEROS16.set(data.subarray(blocks * BLOCK_SIZE));
this._updateBlock(swapLE(ZEROS32[3]), swapLE(ZEROS32[2]), swapLE(ZEROS32[1]), swapLE(ZEROS32[0]));
clean(ZEROS32);
}
return this;
}
digestInto(out) {
aexists(this);
aoutput(out, this);
this.finished = true;
// tmp ugly hack
const { s0, s1, s2, s3 } = this;
const o32 = u32(out);
o32[0] = s0;
o32[1] = s1;
o32[2] = s2;
o32[3] = s3;
return out.reverse();
}
}
function wrapConstructorWithKey(hashCons) {
const hashC = (msg, key) => hashCons(key, msg.length).update(toBytes(msg)).digest();
const tmp = hashCons(new Uint8Array(16), 0);
hashC.outputLen = tmp.outputLen;
hashC.blockLen = tmp.blockLen;
hashC.create = (key, expectedLength) => hashCons(key, expectedLength);
return hashC;
}
/** GHash MAC for AES-GCM. */
export const ghash = wrapConstructorWithKey((key, expectedLength) => new GHASH(key, expectedLength));
/** Polyval MAC for AES-SIV. */
export const polyval = wrapConstructorWithKey((key, expectedLength) => new Polyval(key, expectedLength));
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