Yescrypt WebAssembly Module

Yescrypt / Scrypt WebAssembly Module for Browsers / Node.js

Prerequisites

• Node.js LTS or Browser where WebAssembly is enabled

Install

$ yarn add yescrypt-wasm

or on html header / body

<script src="https://cdn.jsdelivr.net/npm/yescrypt-wasm/lib/yescrypt.umd.min.js"></script>

WASM file is fully embedded on script so that you need to load nothing (and should work with any bundlers without hassle)

Build WASM (optional)

Requires latest Emscripten WASM compiler

$ yarn && yarn build:wasm

Will update .wasm and bundled files

Build library (optional)

Rebuild node.js and web umd bundle files

$ yarn && yarn build

Example Code

import { Yescrypt, bytesToHex } from './lib/index.js';

const getRandomHex = () => Buffer.from(crypto.getRandomValues(new Uint8Array(32)));

async function test() {
    const yescrypt = await Yescrypt.init();

    const passwd = Buffer.from("7000000001e980924e4e1109230383e66d62945ff8e749903bea4336755c00000000000051928aff1b4d72416173a8c3948159a09a73ac3bb556aa6bfbcad1a85da7f4c1d13350531e24031b939b9e2b", "hex");

    console.log(bytesToHex(yescrypt.yescrypt_kdf(passwd, getRandomHex())))
}

test();

Also refer example.html for example of using it on browser.

API

All four methods take the password and salt as Uint8Array/Buffer and honor the explicit byte length (binary-safe — a password containing or sized past a NUL byte is hashed correctly):

yescrypt.scrypt_kdf  (passwd, salt, N?, r?, p?, t?, flags?, g?, dklen?): Uint8Array
yescrypt.yescrypt_kdf(passwd, salt, N?, r?, p?, t?, flags?, g?, dklen?): Uint8Array
yescrypt.scrypt_hash (passwd, salt, N?, r?, p?, t?, flags?, g?): string  // "$y$..." crypt(3) form
yescrypt.yescrypt_hash(passwd, salt, N?, r?, p?, t?, flags?, g?): string

These map directly onto the C yescrypt_params_t (yescrypt-c/yescrypt.h):

| param | meaning | default (scrypt_* / yescrypt_*) | |---------|-------------------------------------------|-------------------------------------| | N | cost (power of two) | 4096 | | r | block size | 32 | | p | parallelism | 1 | | t | extra time without extra memory | 0 | | flags | mode/flavor (see YESCRYPT_* constants) | 0 / YESCRYPT_DEFAULTS | | g | hash-upgrade count | 0 | | dklen | output length in bytes (*_kdf only) | 64 |

Flag constants are exported (YESCRYPT_WORM, YESCRYPT_RW, YESCRYPT_DEFAULTS, the YESCRYPT_ROUNDS_* / GATHER_* / SIMPLE_* / SBOX_* family) and may be OR'ed together to match any C-side configuration. ROM (NROM / shared) is not yet exposed.

Invalid parameters throw a RangeError (N must be a power of two > 1, r * p < 2^30), and a genuine hashing failure throws an Error rather than returning a zeroed/empty result. The WASM module is built with ALLOW_MEMORY_GROWTH, so larger N/r no longer abort the whole instance — they either succeed or surface an out-of-memory Error.

import { Yescrypt, YESCRYPT_DEFAULTS, YESCRYPT_WORM } from './lib/index.js';

const y = await Yescrypt.init();
const passwd = Buffer.from('a'.repeat(20));            // 20-byte password works correctly
const salt = Buffer.from(crypto.getRandomValues(new Uint8Array(16)));

// crypt(3)-style encoded hash for /etc/shadow (yescrypt defaults):
console.log(y.yescrypt_hash(passwd, salt));

// raw 32-byte KDF output with custom flags:
console.log(y.yescrypt_kdf(passwd, salt, 4096, 32, 1, 0, YESCRYPT_DEFAULTS, 0, 32));

References

Yescrypt

scrypt-js

scrypt-wasm