perf: remove asn1.js and use node-forge (#166)

* perf: remove asn1.js from rsa

* fix: tweaks

* fix: it works, but I do not know 100% why

* chore: remove asn1.js

* fix: ensure jwk params encoded as uint

* fix: util tests

* fix: zero pad base64urlToBuffer

* fix: more zero pad

* test: add round trip test

* test: base64url to Buffer with padding

package.json

@@ -38,7 +38,6 @@
   "license": "MIT",
   "dependencies": {
     "asmcrypto.js": "^2.3.2",
-    "asn1.js": "^5.2.0",
     "bn.js": "^5.0.0",
     "browserify-aes": "^1.2.0",
     "bs58": "^4.0.1",

src/keys/ecdh-browser.js

@@ -1,9 +1,9 @@
 'use strict'
 
 const errcode = require('err-code')
+const { Buffer } = require('buffer')
 const webcrypto = require('../webcrypto')
-const BN = require('asn1.js').bignum
-const { toBase64, toBn } = require('../util')
+const { bufferToBase64url, base64urlToBuffer } = require('../util')
 const validateCurveType = require('./validate-curve-type')
 
 const bits = {
@@ -89,8 +89,8 @@ function marshalPublicKey (jwk) {
 
   return Buffer.concat([
     Buffer.from([4]), // uncompressed point
-    toBn(jwk.x).toArrayLike(Buffer, 'be', byteLen),
-    toBn(jwk.y).toArrayLike(Buffer, 'be', byteLen)
+    base64urlToBuffer(jwk.x, byteLen),
+    base64urlToBuffer(jwk.y, byteLen)
   ], 1 + byteLen * 2)
 }
 
@@ -101,20 +101,17 @@ function unmarshalPublicKey (curve, key) {
   if (!key.slice(0, 1).equals(Buffer.from([4]))) {
     throw errcode(new Error('Cannot unmarshal public key - invalid key format'), 'ERR_INVALID_KEY_FORMAT')
   }
-  const x = new BN(key.slice(1, byteLen + 1))
-  const y = new BN(key.slice(1 + byteLen))
 
   return {
     kty: 'EC',
     crv: curve,
-    x: toBase64(x, byteLen),
-    y: toBase64(y, byteLen),
+    x: bufferToBase64url(key.slice(1, byteLen + 1), byteLen),
+    y: bufferToBase64url(key.slice(1 + byteLen), byteLen),
     ext: true
   }
 }
 
-function unmarshalPrivateKey (curve, key) {
-  const result = unmarshalPublicKey(curve, key.public)
-  result.d = toBase64(new BN(key.private))
-  return result
-}
+const unmarshalPrivateKey = (curve, key) => ({
+  ...unmarshalPublicKey(curve, key.public),
+  d: bufferToBase64url(key.private)
+})

src/keys/jwk2pem.js

@@ -1,17 +1,8 @@
 'use strict'
 
 require('node-forge/lib/rsa')
-require('node-forge/lib/util')
-require('node-forge/lib/jsbn')
 const forge = require('node-forge/lib/forge')
-
-function base64urlToBigInteger (str) {
-  var bytes = forge.util.decode64(
-    (str + '==='.slice((str.length + 3) % 4))
-      .replace(/-/g, '+')
-      .replace(/_/g, '/'))
-  return new forge.jsbn.BigInteger(forge.util.bytesToHex(bytes), 16)
-}
+const { base64urlToBigInteger } = require('../util')
 
 function convert (key, types) {
   return types.map(t => base64urlToBigInteger(key[t]))

src/keys/rsa-utils.js

@@ -1,68 +1,27 @@
 'use strict'
 
-const asn1 = require('asn1.js')
-
-const util = require('./../util')
-const toBase64 = util.toBase64
-const toBn = util.toBn
-
-const RSAPrivateKey = asn1.define('RSAPrivateKey', function () {
-  this.seq().obj(
-    this.key('version').int(),
-    this.key('modulus').int(),
-    this.key('publicExponent').int(),
-    this.key('privateExponent').int(),
-    this.key('prime1').int(),
-    this.key('prime2').int(),
-    this.key('exponent1').int(),
-    this.key('exponent2').int(),
-    this.key('coefficient').int()
-  )
-})
-
-const AlgorithmIdentifier = asn1.define('AlgorithmIdentifier', function () {
-  this.seq().obj(
-    this.key('algorithm').objid({
-      '1.2.840.113549.1.1.1': 'rsa'
-    }),
-    this.key('none').optional().null_(),
-    this.key('curve').optional().objid(),
-    this.key('params').optional().seq().obj(
-      this.key('p').int(),
-      this.key('q').int(),
-      this.key('g').int()
-    )
-  )
-})
-
-const PublicKey = asn1.define('RSAPublicKey', function () {
-  this.seq().obj(
-    this.key('algorithm').use(AlgorithmIdentifier),
-    this.key('subjectPublicKey').bitstr()
-  )
-})
-
-const RSAPublicKey = asn1.define('RSAPublicKey', function () {
-  this.seq().obj(
-    this.key('modulus').int(),
-    this.key('publicExponent').int()
-  )
-})
+const { Buffer } = require('buffer')
+require('node-forge/lib/asn1')
+require('node-forge/lib/rsa')
+const forge = require('node-forge/lib/forge')
+const { bigIntegerToUintBase64url, base64urlToBigInteger } = require('./../util')
 
 // Convert a PKCS#1 in ASN1 DER format to a JWK key
 exports.pkcs1ToJwk = function (bytes) {
-  const asn1 = RSAPrivateKey.decode(bytes, 'der')
+  const asn1 = forge.asn1.fromDer(bytes.toString('binary'))
+  const privateKey = forge.pki.privateKeyFromAsn1(asn1)
 
+  // https://tools.ietf.org/html/rfc7518#section-6.3.1
   return {
     kty: 'RSA',
-    n: toBase64(asn1.modulus),
-    e: toBase64(asn1.publicExponent),
-    d: toBase64(asn1.privateExponent),
-    p: toBase64(asn1.prime1),
-    q: toBase64(asn1.prime2),
-    dp: toBase64(asn1.exponent1),
-    dq: toBase64(asn1.exponent2),
-    qi: toBase64(asn1.coefficient),
+    n: bigIntegerToUintBase64url(privateKey.n),
+    e: bigIntegerToUintBase64url(privateKey.e),
+    d: bigIntegerToUintBase64url(privateKey.d),
+    p: bigIntegerToUintBase64url(privateKey.p),
+    q: bigIntegerToUintBase64url(privateKey.q),
+    dp: bigIntegerToUintBase64url(privateKey.dP),
+    dq: bigIntegerToUintBase64url(privateKey.dQ),
+    qi: bigIntegerToUintBase64url(privateKey.qInv),
     alg: 'RS256',
     kid: '2011-04-29'
   }
@@ -70,28 +29,29 @@ exports.pkcs1ToJwk = function (bytes) {
 
 // Convert a JWK key into PKCS#1 in ASN1 DER format
 exports.jwkToPkcs1 = function (jwk) {
-  return RSAPrivateKey.encode({
-    version: 0,
-    modulus: toBn(jwk.n),
-    publicExponent: toBn(jwk.e),
-    privateExponent: toBn(jwk.d),
-    prime1: toBn(jwk.p),
-    prime2: toBn(jwk.q),
-    exponent1: toBn(jwk.dp),
-    exponent2: toBn(jwk.dq),
-    coefficient: toBn(jwk.qi)
-  }, 'der')
+  const asn1 = forge.pki.privateKeyToAsn1({
+    n: base64urlToBigInteger(jwk.n),
+    e: base64urlToBigInteger(jwk.e),
+    d: base64urlToBigInteger(jwk.d),
+    p: base64urlToBigInteger(jwk.p),
+    q: base64urlToBigInteger(jwk.q),
+    dP: base64urlToBigInteger(jwk.dp),
+    dQ: base64urlToBigInteger(jwk.dq),
+    qInv: base64urlToBigInteger(jwk.qi)
+  })
+
+  return Buffer.from(forge.asn1.toDer(asn1).getBytes(), 'binary')
 }
 
 // Convert a PKCIX in ASN1 DER format to a JWK key
 exports.pkixToJwk = function (bytes) {
-  const ndata = PublicKey.decode(bytes, 'der')
-  const asn1 = RSAPublicKey.decode(ndata.subjectPublicKey.data, 'der')
+  const asn1 = forge.asn1.fromDer(bytes.toString('binary'))
+  const publicKey = forge.pki.publicKeyFromAsn1(asn1)
 
   return {
     kty: 'RSA',
-    n: toBase64(asn1.modulus),
-    e: toBase64(asn1.publicExponent),
+    n: bigIntegerToUintBase64url(publicKey.n),
+    e: bigIntegerToUintBase64url(publicKey.e),
     alg: 'RS256',
     kid: '2011-04-29'
   }
@@ -99,16 +59,10 @@ exports.pkixToJwk = function (bytes) {
 
 // Convert a JWK key to PKCIX in ASN1 DER format
 exports.jwkToPkix = function (jwk) {
-  return PublicKey.encode({
-    algorithm: {
-      algorithm: 'rsa',
-      none: null
-    },
-    subjectPublicKey: {
-      data: RSAPublicKey.encode({
-        modulus: toBn(jwk.n),
-        publicExponent: toBn(jwk.e)
-      }, 'der')
-    }
-  }, 'der')
+  const asn1 = forge.pki.publicKeyToAsn1({
+    n: base64urlToBigInteger(jwk.n),
+    e: base64urlToBigInteger(jwk.e)
+  })
+
+  return Buffer.from(forge.asn1.toDer(asn1).getBytes(), 'binary')
 }

src/util.js

@@ -1,20 +1,55 @@
 'use strict'
 
-const BN = require('asn1.js').bignum
+const { Buffer } = require('buffer')
+require('node-forge/lib/util')
+require('node-forge/lib/jsbn')
+const forge = require('node-forge/lib/forge')
 
-// Convert a BN.js instance to a base64 encoded string without padding
+exports.bigIntegerToUintBase64url = (num, len) => {
+  // Call `.abs()` to convert to unsigned
+  let buf = Buffer.from(num.abs().toByteArray()) // toByteArray converts to big endian
+
+  // toByteArray() gives us back a signed array, which will include a leading 0
+  // byte if the most significant bit of the number is 1:
+  // https://docs.microsoft.com/en-us/windows/win32/seccertenroll/about-integer
+  // Our number will always be positive so we should remove the leading padding.
+  buf = buf[0] === 0 ? buf.slice(1) : buf
+
+  if (len != null) {
+    if (buf.length > len) throw new Error('byte array longer than desired length')
+    buf = Buffer.concat([Buffer.alloc(len - buf.length), buf])
+  }
+
+  return exports.bufferToBase64url(buf)
+}
+
+// Convert a Buffer to a base64 encoded string without padding
 // Adapted from https://tools.ietf.org/html/draft-ietf-jose-json-web-signature-41#appendix-C
-exports.toBase64 = function toBase64 (bn, len) {
-  // if len is defined then the bytes are leading-0 padded to the length
-  const s = bn.toArrayLike(Buffer, 'be', len).toString('base64')
-
-  return s
-    .replace(/(=*)$/, '') // Remove any trailing '='s
+exports.bufferToBase64url = buf => {
+  return buf
+    .toString('base64')
+    .split('=')[0] // Remove any trailing '='s
     .replace(/\+/g, '-') // 62nd char of encoding
     .replace(/\//g, '_') // 63rd char of encoding
 }
 
-// Convert a base64 encoded string to a BN.js instance
-exports.toBn = function toBn (str) {
-  return new BN(Buffer.from(str, 'base64'))
+// Convert a base64url encoded string to a BigInteger
+exports.base64urlToBigInteger = str => {
+  const buf = exports.base64urlToBuffer(str)
+  return new forge.jsbn.BigInteger(buf.toString('hex'), 16)
+}
+
+exports.base64urlToBuffer = (str, len) => {
+  str = (str + '==='.slice((str.length + 3) % 4))
+    .replace(/-/g, '+')
+    .replace(/_/g, '/')
+
+  let buf = Buffer.from(str, 'base64')
+
+  if (len != null) {
+    if (buf.length > len) throw new Error('byte array longer than desired length')
+    buf = Buffer.concat([Buffer.alloc(len - buf.length), buf])
+  }
+
+  return buf
 }

test/util.spec.js

@@ -6,26 +6,33 @@ const chai = require('chai')
 const dirtyChai = require('dirty-chai')
 const expect = chai.expect
 chai.use(dirtyChai)
-
+require('node-forge/lib/jsbn')
+const forge = require('node-forge/lib/forge')
 const util = require('../src/util')
-const BN = require('bn.js')
 
 describe('Util', () => {
   let bn
 
-  before((done) => {
-    bn = new BN('dead', 16)
-    done()
+  before(() => {
+    bn = new forge.jsbn.BigInteger('dead', 16)
   })
 
-  it('toBase64', (done) => {
-    expect(util.toBase64(bn)).to.eql('3q0')
-    done()
+  it('should convert BigInteger to a uint base64url encoded string', () => {
+    expect(util.bigIntegerToUintBase64url(bn)).to.eql('3q0')
   })
 
-  it('toBase64 zero padding', (done) => {
-    const bnpad = new BN('ff', 16)
-    expect(util.toBase64(bnpad, 2)).to.eql('AP8')
-    done()
+  it('should convert BigInteger to a uint base64url encoded string with padding', () => {
+    const bnpad = new forge.jsbn.BigInteger('ff', 16)
+    expect(util.bigIntegerToUintBase64url(bnpad, 2)).to.eql('AP8')
+  })
+
+  it('should convert base64url encoded string to BigInteger', () => {
+    const num = util.base64urlToBigInteger('3q0')
+    expect(num.equals(bn)).to.be.true()
+  })
+
+  it('should convert base64url encoded string to Buffer with padding', () => {
+    const buf = util.base64urlToBuffer('AP8', 2)
+    expect(Buffer.from([0, 255])).to.eql(buf)
   })
 })