Universal Module for RSA Cryptography (RSA-OAEP and RSASSA-PSS/PKCS1-V1_5) in JavaScript

WARNING: At this time this solution should be considered suitable for research and experimentation, further code and security review is needed before utilization in a production application.

Introduction and Overview

This library is designed to 'universally' provide an RSA cryptographic functions, i.e., it works both on most modern browsers and on Node.js just by importing from NPM/source code. The original specification is given in RFC5869 (https://tools.ietf.org/html/rfc5869). Note that in the design principle, the library fully utilizes native APIs like WebCrypto API to accelerate its operation if available. This library provides APIs to employ RSA-OAEP, RSA-PSS/RSASSA-PKCS1-v1_5 and their key generation, i.e., sign, verify, encrypt and decrypt.

Installation

At your project directory, do either one of the following.

• From npm/yarn:

  $ npm install --save js-crypto-rsa // npm
  $ yarn add js-crypto-rsa // yarn

• From GitHub:

  $ git clone https://github.com/junkurihara/jscu.git
  $ cd js-crypto-utils/packages/js-crypto-rsa
  & yarn build

Then you should import the package as follows.

import rsa from 'js-crypto-rsa'; // for npm
import rsa from 'path/to/js-crypto-rsa/dist/index.js'; // for github

The bundled file is also given as js-crypto-rsa/dist/jscrsa.bundle.js for a use case where the module is imported as a window.jscrsa object via script tags.

Usage

This library always uses JWK-formatted keys (RFC7517) to do any operations. If you utilize keys of other format, like PEM, please use js-crypto-key-utils to convert them to JWK.

Key generation

rsa.generateKey(2048).then( (key) => {
  // now you get the JWK public and private keys
  const publicKey = key.publicKey;
  const privateKey = key.privateKey;
})

Sign and verify

const publicJwk = {kty: 'RSA', n: '...', e: '...'}; // public key
const privateJwk = {kty: 'RSA', n: '...', e: '...', p: '...', q: '...', dp: '...', dq: '...', qi: '...'}; // paired private key
const msg = ...; // Uint8Array

// sign
rsa.sign(
  msg,
  privateJwk,
  'SHA-256',
  { // optional
    name: 'RSA-PSS', // default. 'RSASSA-PKCS1-v1_5' is also available.
    saltLength: 64
  }
  ).then( (signature) => {
  // now you get the signature in Uint8Array
  return rsa.verify(
    msg,
    sign,
    publicJwk,
    'SHA-256',
      { // optional
        name: 'RSA-PSS', // default. 'RSASSA-PKCS1-v1_5' is also available.
        saltLength: 64 // default is the same as hash length
      }
    );
}).then( (valid) => {
  // now you get the result of verification in boolean
});

Encrypt and decrypt

const publicJwk = {kty: 'RSA', n: '...', e: '...'}; // public key
const privateJwk = {ktyp: 'RSA', n: 'P-256', e: '...', p: '...', q: '...', dp: '...', dq: '...', qi: '...'}; // paired private key
const msg = ...; // Uint8Array

// sign
rsa.encrypt(
  msg,
  publicJwk,
  'SHA-256', // optional, for OAEP. default is 'SHA-256'
  ).then( (encrypted) => {
  // now you get an encrypted message in Uint8Array
    return rsa.decrypt(
      encrypted,
      privateJwk,
      'SHA-256', // optional, for OAEP. default is 'SHA-256'
    );
}).then( (decrypted) => {
  // now you get the decrypted message
});

Note

This library has the following limitations at this point.

• Node.js must be >= v10.12.0 to generate RSA keys.

• Some functions does not work in legacy browsers like older MS Edge. In particular, MS Edge is incompatible with RSA-OAEP and more and more. This library heavily relies on the native (but standardized) implementation of RSA cryptographic modules in browsers and Node.js and it does not employ pure-JS RSA implementations for compatibility yet. Currently, we strongly recommend you to use this library in more modern environments, and, honestly, you should discard the MS Edge ASAP. IE is completely out of our scope.

License

Licensed under the MIT license, see LICENSE file.