162 lines
6.5 KiB
Plaintext
162 lines
6.5 KiB
Plaintext
"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.eskdf = exports.deriveMainSeed = exports.pbkdf2 = exports.scrypt = void 0;
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const _assert_js_1 = require("./_assert.js");
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const hkdf_js_1 = require("./hkdf.js");
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const sha256_js_1 = require("./sha256.js");
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const pbkdf2_js_1 = require("./pbkdf2.js");
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const scrypt_js_1 = require("./scrypt.js");
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const utils_js_1 = require("./utils.js");
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// A tiny KDF for various applications like AES key-gen.
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// Uses HKDF in a non-standard way, so it's not "KDF-secure", only "PRF-secure".
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// Which is good enough: assume sha2-256 retained preimage resistance.
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const SCRYPT_FACTOR = 2 ** 19;
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const PBKDF2_FACTOR = 2 ** 17;
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// Scrypt KDF
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function scrypt(password, salt) {
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return (0, scrypt_js_1.scrypt)(password, salt, { N: SCRYPT_FACTOR, r: 8, p: 1, dkLen: 32 });
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}
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exports.scrypt = scrypt;
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// PBKDF2-HMAC-SHA256
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function pbkdf2(password, salt) {
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return (0, pbkdf2_js_1.pbkdf2)(sha256_js_1.sha256, password, salt, { c: PBKDF2_FACTOR, dkLen: 32 });
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}
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exports.pbkdf2 = pbkdf2;
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// Combines two 32-byte byte arrays
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function xor32(a, b) {
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(0, _assert_js_1.bytes)(a, 32);
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(0, _assert_js_1.bytes)(b, 32);
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const arr = new Uint8Array(32);
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for (let i = 0; i < 32; i++) {
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arr[i] = a[i] ^ b[i];
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}
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return arr;
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}
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function strHasLength(str, min, max) {
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return typeof str === 'string' && str.length >= min && str.length <= max;
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}
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/**
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* Derives main seed. Takes a lot of time. Prefer `eskdf` method instead.
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*/
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function deriveMainSeed(username, password) {
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if (!strHasLength(username, 8, 255))
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throw new Error('invalid username');
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if (!strHasLength(password, 8, 255))
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throw new Error('invalid password');
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const scr = scrypt(password + '\u{1}', username + '\u{1}');
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const pbk = pbkdf2(password + '\u{2}', username + '\u{2}');
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const res = xor32(scr, pbk);
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scr.fill(0);
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pbk.fill(0);
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return res;
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}
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exports.deriveMainSeed = deriveMainSeed;
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/**
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* Converts protocol & accountId pair to HKDF salt & info params.
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*/
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function getSaltInfo(protocol, accountId = 0) {
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// Note that length here also repeats two lines below
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// We do an additional length check here to reduce the scope of DoS attacks
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if (!(strHasLength(protocol, 3, 15) && /^[a-z0-9]{3,15}$/.test(protocol))) {
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throw new Error('invalid protocol');
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}
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// Allow string account ids for some protocols
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const allowsStr = /^password\d{0,3}|ssh|tor|file$/.test(protocol);
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let salt; // Extract salt. Default is undefined.
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if (typeof accountId === 'string') {
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if (!allowsStr)
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throw new Error('accountId must be a number');
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if (!strHasLength(accountId, 1, 255))
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throw new Error('accountId must be valid string');
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salt = (0, utils_js_1.toBytes)(accountId);
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}
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else if (Number.isSafeInteger(accountId)) {
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if (accountId < 0 || accountId > 2 ** 32 - 1)
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throw new Error('invalid accountId');
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// Convert to Big Endian Uint32
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salt = new Uint8Array(4);
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(0, utils_js_1.createView)(salt).setUint32(0, accountId, false);
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}
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else {
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throw new Error(`accountId must be a number${allowsStr ? ' or string' : ''}`);
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}
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const info = (0, utils_js_1.toBytes)(protocol);
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return { salt, info };
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}
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function countBytes(num) {
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if (typeof num !== 'bigint' || num <= BigInt(128))
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throw new Error('invalid number');
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return Math.ceil(num.toString(2).length / 8);
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}
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/**
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* Parses keyLength and modulus options to extract length of result key.
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* If modulus is used, adds 64 bits to it as per FIPS 186 B.4.1 to combat modulo bias.
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*/
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function getKeyLength(options) {
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if (!options || typeof options !== 'object')
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return 32;
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const hasLen = 'keyLength' in options;
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const hasMod = 'modulus' in options;
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if (hasLen && hasMod)
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throw new Error('cannot combine keyLength and modulus options');
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if (!hasLen && !hasMod)
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throw new Error('must have either keyLength or modulus option');
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// FIPS 186 B.4.1 requires at least 64 more bits
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const l = hasMod ? countBytes(options.modulus) + 8 : options.keyLength;
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if (!(typeof l === 'number' && l >= 16 && l <= 8192))
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throw new Error('invalid keyLength');
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return l;
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}
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/**
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* Converts key to bigint and divides it by modulus. Big Endian.
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* Implements FIPS 186 B.4.1, which removes 0 and modulo bias from output.
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*/
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function modReduceKey(key, modulus) {
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const _1 = BigInt(1);
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const num = BigInt('0x' + (0, utils_js_1.bytesToHex)(key)); // check for ui8a, then bytesToNumber()
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const res = (num % (modulus - _1)) + _1; // Remove 0 from output
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if (res < _1)
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throw new Error('expected positive number'); // Guard against bad values
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const len = key.length - 8; // FIPS requires 64 more bits = 8 bytes
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const hex = res.toString(16).padStart(len * 2, '0'); // numberToHex()
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const bytes = (0, utils_js_1.hexToBytes)(hex);
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if (bytes.length !== len)
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throw new Error('invalid length of result key');
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return bytes;
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}
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/**
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* ESKDF
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* @param username - username, email, or identifier, min: 8 characters, should have enough entropy
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* @param password - password, min: 8 characters, should have enough entropy
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* @example
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* const kdf = await eskdf('example-university', 'beginning-new-example');
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* const key = kdf.deriveChildKey('aes', 0);
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* console.log(kdf.fingerprint);
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* kdf.expire();
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*/
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async function eskdf(username, password) {
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// We are using closure + object instead of class because
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// we want to make `seed` non-accessible for any external function.
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let seed = deriveMainSeed(username, password);
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function deriveCK(protocol, accountId = 0, options) {
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(0, _assert_js_1.bytes)(seed, 32);
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const { salt, info } = getSaltInfo(protocol, accountId); // validate protocol & accountId
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const keyLength = getKeyLength(options); // validate options
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const key = (0, hkdf_js_1.hkdf)(sha256_js_1.sha256, seed, salt, info, keyLength);
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// Modulus has already been validated
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return options && 'modulus' in options ? modReduceKey(key, options.modulus) : key;
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}
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function expire() {
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if (seed)
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seed.fill(1);
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seed = undefined;
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}
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// prettier-ignore
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const fingerprint = Array.from(deriveCK('fingerprint', 0))
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.slice(0, 6)
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.map((char) => char.toString(16).padStart(2, '0').toUpperCase())
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.join(':');
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return Object.freeze({ deriveChildKey: deriveCK, expire, fingerprint });
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}
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exports.eskdf = eskdf;
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//# sourceMappingURL=eskdf.js.map |