mirror of https://github.com/gchq/CyberChef.git
145 lines
3.7 KiB
JavaScript
145 lines
3.7 KiB
JavaScript
/**
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* @author joostrijneveld [joost@joostrijneveld.nl]
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* @copyright Crown Copyright 2024
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* @license Apache-2.0
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*/
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import Utils from "../Utils.mjs";
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/**
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* Computes the Salsa20 permute function
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*
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* @param {byteArray} x
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* @param {integer} rounds
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*/
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function salsa20Permute(x, rounds) {
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/**
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* Macro to compute a 32-bit rotate-left operation
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*
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* @param {integer} x
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* @param {integer} n
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* @returns {integer}
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*/
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function ROL32(x, n) {
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return ((x << n) & 0xFFFFFFFF) | (x >>> (32 - n));
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}
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/**
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* Macro to compute a single Salsa20 quarterround operation
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*
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* @param {integer} x
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* @param {integer} a
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* @param {integer} b
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* @param {integer} c
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* @param {integer} d
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* @returns {integer}
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*/
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function quarterround(x, a, b, c, d) {
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x[b] ^= ROL32((x[a] + x[d]) & 0xFFFFFFFF, 7);
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x[c] ^= ROL32((x[b] + x[a]) & 0xFFFFFFFF, 9);
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x[d] ^= ROL32((x[c] + x[b]) & 0xFFFFFFFF, 13);
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x[a] ^= ROL32((x[d] + x[c]) & 0xFFFFFFFF, 18);
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}
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for (let i = 0; i < rounds / 2; i++) {
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quarterround(x, 0, 4, 8, 12);
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quarterround(x, 5, 9, 13, 1);
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quarterround(x, 10, 14, 2, 6);
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quarterround(x, 15, 3, 7, 11);
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quarterround(x, 0, 1, 2, 3);
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quarterround(x, 5, 6, 7, 4);
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quarterround(x, 10, 11, 8, 9);
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quarterround(x, 15, 12, 13, 14);
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}
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}
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/**
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* Computes the Salsa20 block function
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*
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* @param {byteArray} key
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* @param {byteArray} nonce
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* @param {byteArray} counter
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* @param {integer} rounds
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* @returns {byteArray}
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*/
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export function salsa20Block(key, nonce, counter, rounds) {
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const tau = "expand 16-byte k";
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const sigma = "expand 32-byte k";
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let state, c;
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if (key.length === 16) {
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c = Utils.strToByteArray(tau);
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key = key.concat(key);
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} else {
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c = Utils.strToByteArray(sigma);
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}
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state = c.slice(0, 4);
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state = state.concat(key.slice(0, 16));
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state = state.concat(c.slice(4, 8));
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state = state.concat(nonce);
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state = state.concat(counter);
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state = state.concat(c.slice(8, 12));
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state = state.concat(key.slice(16, 32));
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state = state.concat(c.slice(12, 16));
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const x = Array();
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for (let i = 0; i < 64; i += 4) {
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x.push(Utils.byteArrayToInt(state.slice(i, i + 4), "little"));
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}
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const a = [...x];
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salsa20Permute(x, rounds);
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for (let i = 0; i < 16; i++) {
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x[i] = (x[i] + a[i]) & 0xFFFFFFFF;
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}
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let output = Array();
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for (let i = 0; i < 16; i++) {
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output = output.concat(Utils.intToByteArray(x[i], 4, "little"));
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}
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return output;
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}
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/**
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* Computes the hSalsa20 function
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*
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* @param {byteArray} key
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* @param {byteArray} nonce
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* @param {integer} rounds
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* @returns {byteArray}
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*/
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export function hsalsa20(key, nonce, rounds) {
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const tau = "expand 16-byte k";
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const sigma = "expand 32-byte k";
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let state, c;
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if (key.length === 16) {
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c = Utils.strToByteArray(tau);
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key = key.concat(key);
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} else {
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c = Utils.strToByteArray(sigma);
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}
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state = c.slice(0, 4);
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state = state.concat(key.slice(0, 16));
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state = state.concat(c.slice(4, 8));
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state = state.concat(nonce);
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state = state.concat(c.slice(8, 12));
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state = state.concat(key.slice(16, 32));
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state = state.concat(c.slice(12, 16));
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const x = Array();
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for (let i = 0; i < 64; i += 4) {
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x.push(Utils.byteArrayToInt(state.slice(i, i + 4), "little"));
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}
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salsa20Permute(x, rounds);
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let output = Array();
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const idx = [0, 5, 10, 15, 6, 7, 8, 9];
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for (let i = 0; i < 8; i++) {
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output = output.concat(Utils.intToByteArray(x[idx[i]], 4, "little"));
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}
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return output;
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}
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