670 lines
26 KiB
JavaScript
670 lines
26 KiB
JavaScript
// prettier-ignore
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import { wrapCipher, createView, setBigUint64, equalBytes, u32, u8, } from './utils.js';
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import { ghash, polyval } from './_polyval.js';
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import { bytes as abytes } from './_assert.js';
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/*
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AES (Advanced Encryption Standard) aka Rijndael block cipher.
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Data is split into 128-bit blocks. Encrypted in 10/12/14 rounds (128/192/256 bits). In every round:
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1. **S-box**, table substitution
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2. **Shift rows**, cyclic shift left of all rows of data array
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3. **Mix columns**, multiplying every column by fixed polynomial
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4. **Add round key**, round_key xor i-th column of array
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Resources:
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- FIPS-197 https://csrc.nist.gov/files/pubs/fips/197/final/docs/fips-197.pdf
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- Original proposal: https://csrc.nist.gov/csrc/media/projects/cryptographic-standards-and-guidelines/documents/aes-development/rijndael-ammended.pdf
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*/
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const BLOCK_SIZE = 16;
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const BLOCK_SIZE32 = 4;
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const EMPTY_BLOCK = new Uint8Array(BLOCK_SIZE);
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const POLY = 0x11b; // 1 + x + x**3 + x**4 + x**8
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// TODO: remove multiplication, binary ops only
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function mul2(n) {
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return (n << 1) ^ (POLY & -(n >> 7));
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}
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function mul(a, b) {
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let res = 0;
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for (; b > 0; b >>= 1) {
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// Montgomery ladder
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res ^= a & -(b & 1); // if (b&1) res ^=a (but const-time).
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a = mul2(a); // a = 2*a
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}
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return res;
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}
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// AES S-box is generated using finite field inversion,
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// an affine transform, and xor of a constant 0x63.
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const sbox = /* @__PURE__ */ (() => {
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let t = new Uint8Array(256);
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for (let i = 0, x = 1; i < 256; i++, x ^= mul2(x))
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t[i] = x;
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const box = new Uint8Array(256);
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box[0] = 0x63; // first elm
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for (let i = 0; i < 255; i++) {
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let x = t[255 - i];
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x |= x << 8;
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box[t[i]] = (x ^ (x >> 4) ^ (x >> 5) ^ (x >> 6) ^ (x >> 7) ^ 0x63) & 0xff;
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}
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return box;
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})();
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// Inverted S-box
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const invSbox = /* @__PURE__ */ sbox.map((_, j) => sbox.indexOf(j));
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// Rotate u32 by 8
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const rotr32_8 = (n) => (n << 24) | (n >>> 8);
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const rotl32_8 = (n) => (n << 8) | (n >>> 24);
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// T-table is optimization suggested in 5.2 of original proposal (missed from FIPS-197). Changes:
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// - LE instead of BE
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// - bigger tables: T0 and T1 are merged into T01 table and T2 & T3 into T23;
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// so index is u16, instead of u8. This speeds up things, unexpectedly
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function genTtable(sbox, fn) {
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if (sbox.length !== 256)
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throw new Error('Wrong sbox length');
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const T0 = new Uint32Array(256).map((_, j) => fn(sbox[j]));
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const T1 = T0.map(rotl32_8);
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const T2 = T1.map(rotl32_8);
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const T3 = T2.map(rotl32_8);
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const T01 = new Uint32Array(256 * 256);
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const T23 = new Uint32Array(256 * 256);
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const sbox2 = new Uint16Array(256 * 256);
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for (let i = 0; i < 256; i++) {
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for (let j = 0; j < 256; j++) {
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const idx = i * 256 + j;
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T01[idx] = T0[i] ^ T1[j];
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T23[idx] = T2[i] ^ T3[j];
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sbox2[idx] = (sbox[i] << 8) | sbox[j];
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}
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}
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return { sbox, sbox2, T0, T1, T2, T3, T01, T23 };
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}
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const tableEncoding = /* @__PURE__ */ genTtable(sbox, (s) => (mul(s, 3) << 24) | (s << 16) | (s << 8) | mul(s, 2));
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const tableDecoding = /* @__PURE__ */ genTtable(invSbox, (s) => (mul(s, 11) << 24) | (mul(s, 13) << 16) | (mul(s, 9) << 8) | mul(s, 14));
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const xPowers = /* @__PURE__ */ (() => {
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const p = new Uint8Array(16);
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for (let i = 0, x = 1; i < 16; i++, x = mul2(x))
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p[i] = x;
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return p;
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})();
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export function expandKeyLE(key) {
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abytes(key);
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const len = key.length;
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if (![16, 24, 32].includes(len))
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throw new Error(`aes: wrong key size: should be 16, 24 or 32, got: ${len}`);
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const { sbox2 } = tableEncoding;
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const k32 = u32(key);
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const Nk = k32.length;
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const subByte = (n) => applySbox(sbox2, n, n, n, n);
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const xk = new Uint32Array(len + 28); // expanded key
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xk.set(k32);
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// 4.3.1 Key expansion
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for (let i = Nk; i < xk.length; i++) {
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let t = xk[i - 1];
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if (i % Nk === 0)
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t = subByte(rotr32_8(t)) ^ xPowers[i / Nk - 1];
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else if (Nk > 6 && i % Nk === 4)
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t = subByte(t);
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xk[i] = xk[i - Nk] ^ t;
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}
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return xk;
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}
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export function expandKeyDecLE(key) {
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const encKey = expandKeyLE(key);
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const xk = encKey.slice();
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const Nk = encKey.length;
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const { sbox2 } = tableEncoding;
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const { T0, T1, T2, T3 } = tableDecoding;
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// Inverse key by chunks of 4 (rounds)
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for (let i = 0; i < Nk; i += 4) {
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for (let j = 0; j < 4; j++)
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xk[i + j] = encKey[Nk - i - 4 + j];
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}
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encKey.fill(0);
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// apply InvMixColumn except first & last round
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for (let i = 4; i < Nk - 4; i++) {
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const x = xk[i];
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const w = applySbox(sbox2, x, x, x, x);
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xk[i] = T0[w & 0xff] ^ T1[(w >>> 8) & 0xff] ^ T2[(w >>> 16) & 0xff] ^ T3[w >>> 24];
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}
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return xk;
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}
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// Apply tables
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function apply0123(T01, T23, s0, s1, s2, s3) {
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return (T01[((s0 << 8) & 0xff00) | ((s1 >>> 8) & 0xff)] ^
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T23[((s2 >>> 8) & 0xff00) | ((s3 >>> 24) & 0xff)]);
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}
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function applySbox(sbox2, s0, s1, s2, s3) {
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return (sbox2[(s0 & 0xff) | (s1 & 0xff00)] |
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(sbox2[((s2 >>> 16) & 0xff) | ((s3 >>> 16) & 0xff00)] << 16));
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}
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function encrypt(xk, s0, s1, s2, s3) {
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const { sbox2, T01, T23 } = tableEncoding;
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let k = 0;
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(s0 ^= xk[k++]), (s1 ^= xk[k++]), (s2 ^= xk[k++]), (s3 ^= xk[k++]);
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const rounds = xk.length / 4 - 2;
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for (let i = 0; i < rounds; i++) {
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const t0 = xk[k++] ^ apply0123(T01, T23, s0, s1, s2, s3);
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const t1 = xk[k++] ^ apply0123(T01, T23, s1, s2, s3, s0);
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const t2 = xk[k++] ^ apply0123(T01, T23, s2, s3, s0, s1);
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const t3 = xk[k++] ^ apply0123(T01, T23, s3, s0, s1, s2);
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(s0 = t0), (s1 = t1), (s2 = t2), (s3 = t3);
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}
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// last round (without mixcolumns, so using SBOX2 table)
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const t0 = xk[k++] ^ applySbox(sbox2, s0, s1, s2, s3);
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const t1 = xk[k++] ^ applySbox(sbox2, s1, s2, s3, s0);
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const t2 = xk[k++] ^ applySbox(sbox2, s2, s3, s0, s1);
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const t3 = xk[k++] ^ applySbox(sbox2, s3, s0, s1, s2);
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return { s0: t0, s1: t1, s2: t2, s3: t3 };
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}
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function decrypt(xk, s0, s1, s2, s3) {
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const { sbox2, T01, T23 } = tableDecoding;
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let k = 0;
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(s0 ^= xk[k++]), (s1 ^= xk[k++]), (s2 ^= xk[k++]), (s3 ^= xk[k++]);
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const rounds = xk.length / 4 - 2;
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for (let i = 0; i < rounds; i++) {
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const t0 = xk[k++] ^ apply0123(T01, T23, s0, s3, s2, s1);
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const t1 = xk[k++] ^ apply0123(T01, T23, s1, s0, s3, s2);
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const t2 = xk[k++] ^ apply0123(T01, T23, s2, s1, s0, s3);
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const t3 = xk[k++] ^ apply0123(T01, T23, s3, s2, s1, s0);
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(s0 = t0), (s1 = t1), (s2 = t2), (s3 = t3);
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}
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// Last round
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const t0 = xk[k++] ^ applySbox(sbox2, s0, s3, s2, s1);
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const t1 = xk[k++] ^ applySbox(sbox2, s1, s0, s3, s2);
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const t2 = xk[k++] ^ applySbox(sbox2, s2, s1, s0, s3);
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const t3 = xk[k++] ^ applySbox(sbox2, s3, s2, s1, s0);
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return { s0: t0, s1: t1, s2: t2, s3: t3 };
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}
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function getDst(len, dst) {
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if (!dst)
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return new Uint8Array(len);
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abytes(dst);
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if (dst.length < len)
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throw new Error(`aes: wrong destination length, expected at least ${len}, got: ${dst.length}`);
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return dst;
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}
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// TODO: investigate merging with ctr32
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function ctrCounter(xk, nonce, src, dst) {
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abytes(nonce, BLOCK_SIZE);
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abytes(src);
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const srcLen = src.length;
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dst = getDst(srcLen, dst);
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const ctr = nonce;
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const c32 = u32(ctr);
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// Fill block (empty, ctr=0)
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let { s0, s1, s2, s3 } = encrypt(xk, c32[0], c32[1], c32[2], c32[3]);
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const src32 = u32(src);
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const dst32 = u32(dst);
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// process blocks
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for (let i = 0; i + 4 <= src32.length; i += 4) {
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dst32[i + 0] = src32[i + 0] ^ s0;
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dst32[i + 1] = src32[i + 1] ^ s1;
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dst32[i + 2] = src32[i + 2] ^ s2;
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dst32[i + 3] = src32[i + 3] ^ s3;
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// Full 128 bit counter with wrap around
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let carry = 1;
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for (let i = ctr.length - 1; i >= 0; i--) {
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carry = (carry + (ctr[i] & 0xff)) | 0;
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ctr[i] = carry & 0xff;
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carry >>>= 8;
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}
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({ s0, s1, s2, s3 } = encrypt(xk, c32[0], c32[1], c32[2], c32[3]));
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}
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// leftovers (less than block)
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// It's possible to handle > u32 fast, but is it worth it?
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const start = BLOCK_SIZE * Math.floor(src32.length / BLOCK_SIZE32);
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if (start < srcLen) {
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const b32 = new Uint32Array([s0, s1, s2, s3]);
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const buf = u8(b32);
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for (let i = start, pos = 0; i < srcLen; i++, pos++)
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dst[i] = src[i] ^ buf[pos];
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}
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return dst;
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}
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// AES CTR with overflowing 32 bit counter
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// It's possible to do 32le significantly simpler (and probably faster) by using u32.
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// But, we need both, and perf bottleneck is in ghash anyway.
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function ctr32(xk, isLE, nonce, src, dst) {
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abytes(nonce, BLOCK_SIZE);
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abytes(src);
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dst = getDst(src.length, dst);
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const ctr = nonce; // write new value to nonce, so it can be re-used
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const c32 = u32(ctr);
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const view = createView(ctr);
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const src32 = u32(src);
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const dst32 = u32(dst);
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const ctrPos = isLE ? 0 : 12;
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const srcLen = src.length;
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// Fill block (empty, ctr=0)
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let ctrNum = view.getUint32(ctrPos, isLE); // read current counter value
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let { s0, s1, s2, s3 } = encrypt(xk, c32[0], c32[1], c32[2], c32[3]);
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// process blocks
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for (let i = 0; i + 4 <= src32.length; i += 4) {
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dst32[i + 0] = src32[i + 0] ^ s0;
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dst32[i + 1] = src32[i + 1] ^ s1;
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dst32[i + 2] = src32[i + 2] ^ s2;
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dst32[i + 3] = src32[i + 3] ^ s3;
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ctrNum = (ctrNum + 1) >>> 0; // u32 wrap
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view.setUint32(ctrPos, ctrNum, isLE);
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({ s0, s1, s2, s3 } = encrypt(xk, c32[0], c32[1], c32[2], c32[3]));
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}
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// leftovers (less than a block)
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const start = BLOCK_SIZE * Math.floor(src32.length / BLOCK_SIZE32);
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if (start < srcLen) {
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const b32 = new Uint32Array([s0, s1, s2, s3]);
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const buf = u8(b32);
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for (let i = start, pos = 0; i < srcLen; i++, pos++)
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dst[i] = src[i] ^ buf[pos];
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}
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return dst;
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}
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/**
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* CTR: counter mode. Creates stream cipher.
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* Requires good IV. Parallelizable. OK, but no MAC.
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*/
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export const ctr = wrapCipher({ blockSize: 16, nonceLength: 16 }, function ctr(key, nonce) {
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abytes(key);
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abytes(nonce, BLOCK_SIZE);
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function processCtr(buf, dst) {
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const xk = expandKeyLE(key);
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const n = nonce.slice();
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const out = ctrCounter(xk, n, buf, dst);
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xk.fill(0);
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n.fill(0);
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return out;
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}
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return {
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encrypt: (plaintext, dst) => processCtr(plaintext, dst),
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decrypt: (ciphertext, dst) => processCtr(ciphertext, dst),
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};
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});
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function validateBlockDecrypt(data) {
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abytes(data);
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if (data.length % BLOCK_SIZE !== 0) {
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throw new Error(`aes/(cbc-ecb).decrypt ciphertext should consist of blocks with size ${BLOCK_SIZE}`);
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}
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}
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function validateBlockEncrypt(plaintext, pcks5, dst) {
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let outLen = plaintext.length;
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const remaining = outLen % BLOCK_SIZE;
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if (!pcks5 && remaining !== 0)
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throw new Error('aec/(cbc-ecb): unpadded plaintext with disabled padding');
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const b = u32(plaintext);
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if (pcks5) {
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let left = BLOCK_SIZE - remaining;
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if (!left)
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left = BLOCK_SIZE; // if no bytes left, create empty padding block
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outLen = outLen + left;
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}
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const out = getDst(outLen, dst);
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const o = u32(out);
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return { b, o, out };
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}
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function validatePCKS(data, pcks5) {
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if (!pcks5)
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return data;
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const len = data.length;
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if (!len)
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throw new Error(`aes/pcks5: empty ciphertext not allowed`);
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const lastByte = data[len - 1];
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if (lastByte <= 0 || lastByte > 16)
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throw new Error(`aes/pcks5: wrong padding byte: ${lastByte}`);
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const out = data.subarray(0, -lastByte);
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for (let i = 0; i < lastByte; i++)
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if (data[len - i - 1] !== lastByte)
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throw new Error(`aes/pcks5: wrong padding`);
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return out;
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}
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function padPCKS(left) {
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const tmp = new Uint8Array(16);
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const tmp32 = u32(tmp);
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tmp.set(left);
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const paddingByte = BLOCK_SIZE - left.length;
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for (let i = BLOCK_SIZE - paddingByte; i < BLOCK_SIZE; i++)
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tmp[i] = paddingByte;
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return tmp32;
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}
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/**
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* ECB: Electronic CodeBook. Simple deterministic replacement.
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* Dangerous: always map x to y. See [AES Penguin](https://words.filippo.io/the-ecb-penguin/).
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*/
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export const ecb = wrapCipher({ blockSize: 16 }, function ecb(key, opts = {}) {
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abytes(key);
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const pcks5 = !opts.disablePadding;
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return {
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encrypt: (plaintext, dst) => {
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abytes(plaintext);
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const { b, o, out: _out } = validateBlockEncrypt(plaintext, pcks5, dst);
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const xk = expandKeyLE(key);
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let i = 0;
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for (; i + 4 <= b.length;) {
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const { s0, s1, s2, s3 } = encrypt(xk, b[i + 0], b[i + 1], b[i + 2], b[i + 3]);
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(o[i++] = s0), (o[i++] = s1), (o[i++] = s2), (o[i++] = s3);
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}
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if (pcks5) {
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const tmp32 = padPCKS(plaintext.subarray(i * 4));
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const { s0, s1, s2, s3 } = encrypt(xk, tmp32[0], tmp32[1], tmp32[2], tmp32[3]);
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(o[i++] = s0), (o[i++] = s1), (o[i++] = s2), (o[i++] = s3);
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}
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xk.fill(0);
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return _out;
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},
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decrypt: (ciphertext, dst) => {
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validateBlockDecrypt(ciphertext);
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const xk = expandKeyDecLE(key);
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const out = getDst(ciphertext.length, dst);
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const b = u32(ciphertext);
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const o = u32(out);
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for (let i = 0; i + 4 <= b.length;) {
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const { s0, s1, s2, s3 } = decrypt(xk, b[i + 0], b[i + 1], b[i + 2], b[i + 3]);
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(o[i++] = s0), (o[i++] = s1), (o[i++] = s2), (o[i++] = s3);
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}
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xk.fill(0);
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return validatePCKS(out, pcks5);
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},
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};
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});
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/**
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* CBC: Cipher-Block-Chaining. Key is previous round’s block.
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* Fragile: needs proper padding. Unauthenticated: needs MAC.
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*/
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export const cbc = wrapCipher({ blockSize: 16, nonceLength: 16 }, function cbc(key, iv, opts = {}) {
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abytes(key);
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abytes(iv, 16);
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const pcks5 = !opts.disablePadding;
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return {
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encrypt: (plaintext, dst) => {
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const xk = expandKeyLE(key);
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const { b, o, out: _out } = validateBlockEncrypt(plaintext, pcks5, dst);
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const n32 = u32(iv);
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// prettier-ignore
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let s0 = n32[0], s1 = n32[1], s2 = n32[2], s3 = n32[3];
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let i = 0;
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for (; i + 4 <= b.length;) {
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||
(s0 ^= b[i + 0]), (s1 ^= b[i + 1]), (s2 ^= b[i + 2]), (s3 ^= b[i + 3]);
|
||
({ s0, s1, s2, s3 } = encrypt(xk, s0, s1, s2, s3));
|
||
(o[i++] = s0), (o[i++] = s1), (o[i++] = s2), (o[i++] = s3);
|
||
}
|
||
if (pcks5) {
|
||
const tmp32 = padPCKS(plaintext.subarray(i * 4));
|
||
(s0 ^= tmp32[0]), (s1 ^= tmp32[1]), (s2 ^= tmp32[2]), (s3 ^= tmp32[3]);
|
||
({ s0, s1, s2, s3 } = encrypt(xk, s0, s1, s2, s3));
|
||
(o[i++] = s0), (o[i++] = s1), (o[i++] = s2), (o[i++] = s3);
|
||
}
|
||
xk.fill(0);
|
||
return _out;
|
||
},
|
||
decrypt: (ciphertext, dst) => {
|
||
validateBlockDecrypt(ciphertext);
|
||
const xk = expandKeyDecLE(key);
|
||
const n32 = u32(iv);
|
||
const out = getDst(ciphertext.length, dst);
|
||
const b = u32(ciphertext);
|
||
const o = u32(out);
|
||
// prettier-ignore
|
||
let s0 = n32[0], s1 = n32[1], s2 = n32[2], s3 = n32[3];
|
||
for (let i = 0; i + 4 <= b.length;) {
|
||
// prettier-ignore
|
||
const ps0 = s0, ps1 = s1, ps2 = s2, ps3 = s3;
|
||
(s0 = b[i + 0]), (s1 = b[i + 1]), (s2 = b[i + 2]), (s3 = b[i + 3]);
|
||
const { s0: o0, s1: o1, s2: o2, s3: o3 } = decrypt(xk, s0, s1, s2, s3);
|
||
(o[i++] = o0 ^ ps0), (o[i++] = o1 ^ ps1), (o[i++] = o2 ^ ps2), (o[i++] = o3 ^ ps3);
|
||
}
|
||
xk.fill(0);
|
||
return validatePCKS(out, pcks5);
|
||
},
|
||
};
|
||
});
|
||
/**
|
||
* CFB: Cipher Feedback Mode. The input for the block cipher is the previous cipher output.
|
||
* Unauthenticated: needs MAC.
|
||
*/
|
||
export const cfb = wrapCipher({ blockSize: 16, nonceLength: 16 }, function cfb(key, iv) {
|
||
abytes(key);
|
||
abytes(iv, 16);
|
||
function processCfb(src, isEncrypt, dst) {
|
||
const xk = expandKeyLE(key);
|
||
const srcLen = src.length;
|
||
dst = getDst(srcLen, dst);
|
||
const src32 = u32(src);
|
||
const dst32 = u32(dst);
|
||
const next32 = isEncrypt ? dst32 : src32;
|
||
const n32 = u32(iv);
|
||
// prettier-ignore
|
||
let s0 = n32[0], s1 = n32[1], s2 = n32[2], s3 = n32[3];
|
||
for (let i = 0; i + 4 <= src32.length;) {
|
||
const { s0: e0, s1: e1, s2: e2, s3: e3 } = encrypt(xk, s0, s1, s2, s3);
|
||
dst32[i + 0] = src32[i + 0] ^ e0;
|
||
dst32[i + 1] = src32[i + 1] ^ e1;
|
||
dst32[i + 2] = src32[i + 2] ^ e2;
|
||
dst32[i + 3] = src32[i + 3] ^ e3;
|
||
(s0 = next32[i++]), (s1 = next32[i++]), (s2 = next32[i++]), (s3 = next32[i++]);
|
||
}
|
||
// leftovers (less than block)
|
||
const start = BLOCK_SIZE * Math.floor(src32.length / BLOCK_SIZE32);
|
||
if (start < srcLen) {
|
||
({ s0, s1, s2, s3 } = encrypt(xk, s0, s1, s2, s3));
|
||
const buf = u8(new Uint32Array([s0, s1, s2, s3]));
|
||
for (let i = start, pos = 0; i < srcLen; i++, pos++)
|
||
dst[i] = src[i] ^ buf[pos];
|
||
buf.fill(0);
|
||
}
|
||
xk.fill(0);
|
||
return dst;
|
||
}
|
||
return {
|
||
encrypt: (plaintext, dst) => processCfb(plaintext, true, dst),
|
||
decrypt: (ciphertext, dst) => processCfb(ciphertext, false, dst),
|
||
};
|
||
});
|
||
// TODO: merge with chacha, however gcm has bitLen while chacha has byteLen
|
||
function computeTag(fn, isLE, key, data, AAD) {
|
||
const h = fn.create(key, data.length + (AAD?.length || 0));
|
||
if (AAD)
|
||
h.update(AAD);
|
||
h.update(data);
|
||
const num = new Uint8Array(16);
|
||
const view = createView(num);
|
||
if (AAD)
|
||
setBigUint64(view, 0, BigInt(AAD.length * 8), isLE);
|
||
setBigUint64(view, 8, BigInt(data.length * 8), isLE);
|
||
h.update(num);
|
||
return h.digest();
|
||
}
|
||
/**
|
||
* GCM: Galois/Counter Mode.
|
||
* Good, modern version of CTR, parallel, with MAC.
|
||
* Be careful: MACs can be forged.
|
||
*/
|
||
export const gcm = wrapCipher({ blockSize: 16, nonceLength: 12, tagLength: 16 }, function gcm(key, nonce, AAD) {
|
||
abytes(nonce);
|
||
// Nonce can be pretty much anything (even 1 byte). But smaller nonces less secure.
|
||
if (nonce.length === 0)
|
||
throw new Error('aes/gcm: empty nonce');
|
||
const tagLength = 16;
|
||
function _computeTag(authKey, tagMask, data) {
|
||
const tag = computeTag(ghash, false, authKey, data, AAD);
|
||
for (let i = 0; i < tagMask.length; i++)
|
||
tag[i] ^= tagMask[i];
|
||
return tag;
|
||
}
|
||
function deriveKeys() {
|
||
const xk = expandKeyLE(key);
|
||
const authKey = EMPTY_BLOCK.slice();
|
||
const counter = EMPTY_BLOCK.slice();
|
||
ctr32(xk, false, counter, counter, authKey);
|
||
if (nonce.length === 12) {
|
||
counter.set(nonce);
|
||
}
|
||
else {
|
||
// Spec (NIST 800-38d) supports variable size nonce.
|
||
// Not supported for now, but can be useful.
|
||
const nonceLen = EMPTY_BLOCK.slice();
|
||
const view = createView(nonceLen);
|
||
setBigUint64(view, 8, BigInt(nonce.length * 8), false);
|
||
// ghash(nonce || u64be(0) || u64be(nonceLen*8))
|
||
ghash.create(authKey).update(nonce).update(nonceLen).digestInto(counter);
|
||
}
|
||
const tagMask = ctr32(xk, false, counter, EMPTY_BLOCK);
|
||
return { xk, authKey, counter, tagMask };
|
||
}
|
||
return {
|
||
encrypt: (plaintext) => {
|
||
abytes(plaintext);
|
||
const { xk, authKey, counter, tagMask } = deriveKeys();
|
||
const out = new Uint8Array(plaintext.length + tagLength);
|
||
ctr32(xk, false, counter, plaintext, out);
|
||
const tag = _computeTag(authKey, tagMask, out.subarray(0, out.length - tagLength));
|
||
out.set(tag, plaintext.length);
|
||
xk.fill(0);
|
||
return out;
|
||
},
|
||
decrypt: (ciphertext) => {
|
||
abytes(ciphertext);
|
||
if (ciphertext.length < tagLength)
|
||
throw new Error(`aes/gcm: ciphertext less than tagLen (${tagLength})`);
|
||
const { xk, authKey, counter, tagMask } = deriveKeys();
|
||
const data = ciphertext.subarray(0, -tagLength);
|
||
const passedTag = ciphertext.subarray(-tagLength);
|
||
const tag = _computeTag(authKey, tagMask, data);
|
||
if (!equalBytes(tag, passedTag))
|
||
throw new Error('aes/gcm: invalid ghash tag');
|
||
const out = ctr32(xk, false, counter, data);
|
||
authKey.fill(0);
|
||
tagMask.fill(0);
|
||
xk.fill(0);
|
||
return out;
|
||
},
|
||
};
|
||
});
|
||
const limit = (name, min, max) => (value) => {
|
||
if (!Number.isSafeInteger(value) || min > value || value > max)
|
||
throw new Error(`${name}: invalid value=${value}, must be [${min}..${max}]`);
|
||
};
|
||
/**
|
||
* AES-GCM-SIV: classic AES-GCM with nonce-misuse resistance.
|
||
* Guarantees that, when a nonce is repeated, the only security loss is that identical
|
||
* plaintexts will produce identical ciphertexts.
|
||
* RFC 8452, https://datatracker.ietf.org/doc/html/rfc8452
|
||
*/
|
||
export const siv = wrapCipher({ blockSize: 16, nonceLength: 12, tagLength: 16 }, function siv(key, nonce, AAD) {
|
||
const tagLength = 16;
|
||
// From RFC 8452: Section 6
|
||
const AAD_LIMIT = limit('AAD', 0, 2 ** 36);
|
||
const PLAIN_LIMIT = limit('plaintext', 0, 2 ** 36);
|
||
const NONCE_LIMIT = limit('nonce', 12, 12);
|
||
const CIPHER_LIMIT = limit('ciphertext', 16, 2 ** 36 + 16);
|
||
abytes(nonce);
|
||
NONCE_LIMIT(nonce.length);
|
||
if (AAD) {
|
||
abytes(AAD);
|
||
AAD_LIMIT(AAD.length);
|
||
}
|
||
function deriveKeys() {
|
||
const len = key.length;
|
||
if (len !== 16 && len !== 24 && len !== 32)
|
||
throw new Error(`key length must be 16, 24 or 32 bytes, got: ${len} bytes`);
|
||
const xk = expandKeyLE(key);
|
||
const encKey = new Uint8Array(len);
|
||
const authKey = new Uint8Array(16);
|
||
const n32 = u32(nonce);
|
||
// prettier-ignore
|
||
let s0 = 0, s1 = n32[0], s2 = n32[1], s3 = n32[2];
|
||
let counter = 0;
|
||
for (const derivedKey of [authKey, encKey].map(u32)) {
|
||
const d32 = u32(derivedKey);
|
||
for (let i = 0; i < d32.length; i += 2) {
|
||
// aes(u32le(0) || nonce)[:8] || aes(u32le(1) || nonce)[:8] ...
|
||
const { s0: o0, s1: o1 } = encrypt(xk, s0, s1, s2, s3);
|
||
d32[i + 0] = o0;
|
||
d32[i + 1] = o1;
|
||
s0 = ++counter; // increment counter inside state
|
||
}
|
||
}
|
||
xk.fill(0);
|
||
return { authKey, encKey: expandKeyLE(encKey) };
|
||
}
|
||
function _computeTag(encKey, authKey, data) {
|
||
const tag = computeTag(polyval, true, authKey, data, AAD);
|
||
// Compute the expected tag by XORing S_s and the nonce, clearing the
|
||
// most significant bit of the last byte and encrypting with the
|
||
// message-encryption key.
|
||
for (let i = 0; i < 12; i++)
|
||
tag[i] ^= nonce[i];
|
||
tag[15] &= 0x7f; // Clear the highest bit
|
||
// encrypt tag as block
|
||
const t32 = u32(tag);
|
||
// prettier-ignore
|
||
let s0 = t32[0], s1 = t32[1], s2 = t32[2], s3 = t32[3];
|
||
({ s0, s1, s2, s3 } = encrypt(encKey, s0, s1, s2, s3));
|
||
(t32[0] = s0), (t32[1] = s1), (t32[2] = s2), (t32[3] = s3);
|
||
return tag;
|
||
}
|
||
// actual decrypt/encrypt of message.
|
||
function processSiv(encKey, tag, input) {
|
||
let block = tag.slice();
|
||
block[15] |= 0x80; // Force highest bit
|
||
return ctr32(encKey, true, block, input);
|
||
}
|
||
return {
|
||
encrypt: (plaintext) => {
|
||
abytes(plaintext);
|
||
PLAIN_LIMIT(plaintext.length);
|
||
const { encKey, authKey } = deriveKeys();
|
||
const tag = _computeTag(encKey, authKey, plaintext);
|
||
const out = new Uint8Array(plaintext.length + tagLength);
|
||
out.set(tag, plaintext.length);
|
||
out.set(processSiv(encKey, tag, plaintext));
|
||
encKey.fill(0);
|
||
authKey.fill(0);
|
||
return out;
|
||
},
|
||
decrypt: (ciphertext) => {
|
||
abytes(ciphertext);
|
||
CIPHER_LIMIT(ciphertext.length);
|
||
const tag = ciphertext.subarray(-tagLength);
|
||
const { encKey, authKey } = deriveKeys();
|
||
const plaintext = processSiv(encKey, tag, ciphertext.subarray(0, -tagLength));
|
||
const expectedTag = _computeTag(encKey, authKey, plaintext);
|
||
encKey.fill(0);
|
||
authKey.fill(0);
|
||
if (!equalBytes(tag, expectedTag))
|
||
throw new Error('invalid polyval tag');
|
||
return plaintext;
|
||
},
|
||
};
|
||
});
|
||
function isBytes32(a) {
|
||
return (a != null &&
|
||
typeof a === 'object' &&
|
||
(a instanceof Uint32Array || a.constructor.name === 'Uint32Array'));
|
||
}
|
||
function encryptBlock(xk, block) {
|
||
abytes(block, 16);
|
||
if (!isBytes32(xk))
|
||
throw new Error('_encryptBlock accepts result of expandKeyLE');
|
||
const b32 = u32(block);
|
||
let { s0, s1, s2, s3 } = encrypt(xk, b32[0], b32[1], b32[2], b32[3]);
|
||
(b32[0] = s0), (b32[1] = s1), (b32[2] = s2), (b32[3] = s3);
|
||
return block;
|
||
}
|
||
function decryptBlock(xk, block) {
|
||
abytes(block, 16);
|
||
if (!isBytes32(xk))
|
||
throw new Error('_decryptBlock accepts result of expandKeyLE');
|
||
const b32 = u32(block);
|
||
let { s0, s1, s2, s3 } = decrypt(xk, b32[0], b32[1], b32[2], b32[3]);
|
||
(b32[0] = s0), (b32[1] = s1), (b32[2] = s2), (b32[3] = s3);
|
||
return block;
|
||
}
|
||
// Highly unsafe private functions for implementing new modes or ciphers based on AES
|
||
// Can change at any time, no API guarantees
|
||
export const unsafe = {
|
||
expandKeyLE,
|
||
expandKeyDecLE,
|
||
encrypt,
|
||
decrypt,
|
||
encryptBlock,
|
||
decryptBlock,
|
||
ctrCounter,
|
||
ctr32,
|
||
};
|
||
//# sourceMappingURL=aes.js.map
|