scrypt-async

Fast "async" scrypt implementation in JavaScript.

Works in browsers without throwing "kill slow script" warnings due to configurable interruptStep, which yields from calculation. Compatible even with old versions of IE. Also works with Node.js (but you should really use the C implementation for that).

Installation

You can install it via a package manager:

NPM:

$ npm install scrypt-async

Yarn:

$ yarn add scrypt-async

or download source code.

To improve performance with small interruptStep values, use setImmediate shim, such as https://github.com/YuzuJS/setImmediate.

Usage

Modern API

scrypt(password, salt, options, callback)

Derives a key from password and salt and calls callback with derived key as the only argument.

If interruptStep is set, calculations are interrupted with setImmediate (or zero setTimeout) at the given interruptSteps to avoid freezing the browser. If it's not set or set to zero, the callback is called immediately after the calculation, avoiding setImmediate.

Arguments:

• password — password (string or Array of bytes or Uint8Array)
• salt — salt (string or Array of bytes or Uint8Array)
• options — object with key derivation options
• callback — callback function receiving result (function (Array|Uint8Array|string))

Options:

• N — CPU/memory cost parameter (must be power of two; alternatively, you can specify logN where N = 2^logN).
• r — block size parameter
• p — parallelization parameter (default is 1)
• dkLen — derived key length (default is 32)
• interruptStep — (optional) the amount of loop cycles to execute before the next setImmediate/setTimeout (defaults to 0)
• encoding — (optional) result encoding 'base64' or 'hex' (result will be a string), 'binary' (result will be a Uint8Array) or undefined (result will be an Array of bytes).

Example:

scrypt('mypassword', 'saltysalt', {
    N: 16384,
    r: 8,
    p: 1,
    dkLen: 16,
    encoding: 'hex'
}, function(derivedKey) {
    console.log(derivedKey); // "5012b74fca8ec8a4a0a62ffdeeee959d"
});

Legacy API (deprecated)

scrypt(password, salt, logN, r, dkLen, [interruptStep], callback, [encoding])

Legacy API doesn't support parallelization parameter greater than 1.

Arguments:

• password — password (string or Array of bytes or Uint8Array)
• salt — salt (string or Array of bytes or Uint8Array)
• logN — CPU/memory cost parameter (1 to 31)
• r — block size parameter
• dkLen — length of derived key
• interruptStep — (optional) the amount of loop cycles to execute before the next setImmediate/setTimeout (defaults to 1000)
• callback — callback function receiving result (function (Array|Uint8Array|string))
• encoding — (optional) result encoding ('base64', 'hex', 'binary' or undefined).

When encoding is not set, the result is an Array of bytes.

License

BSD-like, see LICENSE file or MIT license at your choice.