Refactor RSA verification: Replace jsrsasign with crypto-js

package.json

@@ -48,7 +48,8 @@
   },
   "dependencies": {
     "base-64": "^0.1.0",
-    "jsrsasign": "8.0.12",
+    "crypto-js": "^3.1.9-1",
+    "jsbn": "^1.1.0",
     "jwt-decode": "^2.2.0",
     "url": "^0.11.0"
   },

src/jwt/__tests__/base64.spec.js

@@ -0,0 +1,31 @@
+import * as base64 from '../base64';
+
+describe('helpers base64 url', function() {
+  describe('padding', function() {
+    it('does not add to multiple of 4', function() {
+      expect(base64.padding('')).toBe('');
+      expect(base64.padding('abcd')).toBe('abcd');
+    });
+    it('adds to non multiple of 4', function() {
+      expect(base64.padding('a')).toBe('a===');
+      expect(base64.padding('ab')).toBe('ab==');
+      expect(base64.padding('abc')).toBe('abc=');
+      expect(base64.padding('abced')).toBe('abced===');
+    });
+    it('does not change already padded value', function() {
+      const padded = base64.padding('abc');
+      expect(padded).toBe('abc=');
+      const again = base64.padding(padded);
+      expect(again).toBe('abc=');
+    });
+  });
+
+  describe('decoding to hex', function() {
+    it('should convert base64 input into hex output', function() {
+      expect(base64.decodeToHEX('AQAB')).toBe('010001');
+      expect(base64.decodeToHEX('uGbXWiK3dQTyCbX5')).toBe(
+        'b866d75a22b77504f209b5f9',
+      );
+    });
+  });
+});

src/jwt/__tests__/jwks.json

@@ -0,0 +1,12 @@
+{
+  "keys": [
+    {
+      "use": "sig",
+      "alg": "RS256",
+      "kty": "RSA",
+      "e": "AQAB",
+      "kid": "1234",
+      "n": "uGbXWiK3dQTyCbX5xdE4yCuYp0AF2d15Qq1JSXT_lx8CEcXb9RbDddl8jGDv-spi5qPa8qEHiK7FwV2KpRE983wGPnYsAm9BxLFb4YrLYcDFOIGULuk2FtrPS512Qea1bXASuvYXEpQNpGbnTGVsWXI9C-yjHztqyL2h8P6mlThPY9E9ue2fCqdgixfTFIF9Dm4SLHbphUS2iw7w1JgT69s7of9-I9l5lsJ9cozf1rxrXX4V1u_SotUuNB3Fp8oB4C1fLBEhSlMcUJirz1E8AziMCxS-VrRPDM-zfvpIJg3JljAh3PJHDiLu902v9w-Iplu1WyoB2aPfitxEhRN0Yw"
+    }
+  ]
+}

src/jwt/__tests__/jwt.spec.js

@@ -1,7 +1,6 @@
 import verifyToken from '../index';
 import * as signatureVerifier from '../signatureVerifier';
 const jwtDecoder = require('jwt-decode');
-import {KEYUTIL} from 'jsrsasign';
 import * as fs from 'fs';
 import * as path from 'path';
 import fetchMock from 'fetch-mock';
@@ -12,16 +11,6 @@ describe('id token verification tests', () => {
       fetchMock.restore();
     });
 
-    it('uses fixed version of jsrsasign', () => {
-      // jsrsasign has not been updated recently; we want to verify that the dependency is pinned to 8.0.12
-      const packageData = fs.readFileSync(
-        path.resolve(__dirname, '../../../package.json'),
-      );
-      const packageJson = JSON.parse(packageData);
-      const jsrsasignDepVersion = packageJson.dependencies.jsrsasign;
-      expect(jsrsasignDepVersion).toBe('8.0.12');
-    });
-
     it('resolves when no idToken present', async () => {
       await expect(verify(undefined)).resolves.toBeUndefined();
     });
@@ -70,7 +59,7 @@ describe('id token verification tests', () => {
       const testJwt =
         'eyJhbGciOiJSUzI1NiIsImtpZCI6IjEyMzQifQ.eyJpc3MiOiJodHRwczovL3Rva2Vucy10ZXN0LmF1dGgwLmNvbS8iLCJzdWIiOiJhdXRoMHwxMjM0NTY3ODkiLCJhdWQiOlsidG9rZW5zLXRlc3QtMTIzIiwiZXh0ZXJuYWwtdGVzdC0xMjMiXSwiZXhwIjoxNTcwMjAyOTMxLCJpYXQiOjE1NzAwMzAxMzEsIm5vbmNlIjoiYTU5dms1OTIiLCJhenAiOiJ0b2tlbnMtdGVzdC0xMjMiLCJhdXRoX3RpbWUiOjE1NzAxMTY1MzAuNzk2fQ.Xad-J3PtImY3z--Gvj-H61tH18mCGQUUBkcug-CB5ehkjd56PXrA-AJHZK7OLryB_uj6sFKVn-V8Wr6t3KW7_Fd2n-__Ca2h6PtgIrjceZlHAQY4SgAk9tPmeeTOhs6KyXDeW0Ot0j3CP9p7nWxgCGMu_H5J5ZgJSVUVlffVpaIMEGiFZ_r71PLPtuTL3GsDwtICG_5xuqoR2YBLSpNuuc46t15i94E3JC1UXGryRfxVbeHg3x5DF9nf6eVkMHRdi-CdNQn2iD0G9OmxxELh-40pecbyUxLv4NfTHmbxOdvWRK00N8sgkElnPnoWXb5pacxLShFsBTJdXIsyqF_onA';
 
-      const jwks = getJwks();
+      const jwks = getExpectedJwks();
       jwks.keys[0].kid = '4321';
 
       setupFetchMock({jwks});
@@ -86,14 +75,31 @@ describe('id token verification tests', () => {
       );
     });
 
-    it('fails when signature is not verified', async () => {
+    it('fails when public key is invalid and cannot be reconstructed', async () => {
       const testJwt =
         'eyJhbGciOiJSUzI1NiIsImtpZCI6IjEyMzQifQ.eyJpc3MiOiJodHRwczovL3Rva2Vucy10ZXN0LmF1dGgwLmNvbS8iLCJzdWIiOiJhdXRoMHwxMjM0NTY3ODkiLCJhdWQiOlsidG9rZW5zLXRlc3QtMTIzIiwiZXh0ZXJuYWwtdGVzdC0xMjMiXSwiZXhwIjoxNTcwMjAzMjgxLCJpYXQiOjE1NzAwMzA0ODEsIm5vbmNlIjoiYTU5dms1OTIiLCJhenAiOiJ0b2tlbnMtdGVzdC0xMjMiLCJhdXRoX3RpbWUiOjE1NzAxMTY4ODAuNjk0fQ.ZNPsQq_U8NGyi5WFNgvuT0QlxfGFS9w6YIHWiF4dnwz_Zf3mv3gh4wybDR8vaLCE8ONTXvT9V_rW6oqNHSvEwa0nvPy2Vi3gVAvSfusoiYhkuQG_6SuqbeOrNJ1cejGzqw_iv2s6yEyN3B9wp0TCuIKL5jLPttaRi6ouGCbYeReANecaLOVZstrO4GhlY0NwtT4j5Dn1tDYavWxi1DZBisxBvMEFA6N0aQa51gJm6RYtUjBTo50j1xG5b7TIF4edjjT85FYQgrwEzA7Ss3HpnrYXEEvHn4nCsc585T3GKQuF21Nli-qGgQ3MywPOOqqiCSvL254Cp88Gt3xDS1hnqg';
-      const jwks = getJwks();
-      jwks.keys[0].n += 'bad';
+      const jwks = getExpectedJwks();
+      jwks.keys[0].n = 'bad-modulus';
 
       setupFetchMock({jwks});
 
+      const result = verify(testJwt);
+      expect(result).rejects.toHaveProperty(
+        'name',
+        'a0.idtoken.invalid_signature',
+      );
+      expect(result).rejects.toHaveProperty(
+        'message',
+        'Invalid ID token signature',
+      );
+    });
+
+    it('fails when signature is invalid', async () => {
+      const testJwt =
+        'eyJhbGciOiJSUzI1NiIsImtpZCI6IjEyMzQifQ.eyJpc3MiOiJodHRwczovL3Rva2Vucy10ZXN0LmF1dGgwLmNvbS8iLCJzdWIiOiJhdXRoMHwxMjM0NTY3ODkiLCJhdWQiOlsidG9rZW5zLXRlc3QtMTIzIiwiZXh0ZXJuYWwtdGVzdC0xMjMiXSwiZXhwIjoxNTcwMjAzMjgxLCJpYXQiOjE1NzAwMzA0ODEsIm5vbmNlIjoiYTU5dms1OTIiLCJhenAiOiJ0b2tlbnMtdGVzdC0xMjMiLCJhdXRoX3RpbWUiOjE1NzAxMTY4ODAuNjk0fQ.invalid-signature';
+
+      setupFetchMock();
+
       await expect(verify(testJwt)).rejects.toHaveProperty(
         'name',
         'a0.idtoken.invalid_signature',
@@ -114,53 +120,11 @@ describe('id token verification tests', () => {
     it('passes verification with valid token signed with RS256', async () => {
       const testJwt =
         'eyJhbGciOiJSUzI1NiIsImtpZCI6IjEyMzQifQ.eyJpc3MiOiJodHRwczovL3Rva2Vucy10ZXN0LmF1dGgwLmNvbS8iLCJzdWIiOiJhdXRoMHwxMjM0NTY3ODkiLCJhdWQiOlsidG9rZW5zLXRlc3QtMTIzIiwiZXh0ZXJuYWwtdGVzdC0xMjMiXSwiZXhwIjoxNTY3NDg2ODAwLCJpYXQiOjE1NjczMTQwMDAsIm5vbmNlIjoiYTU5dms1OTIiLCJhenAiOiJ0b2tlbnMtdGVzdC0xMjMiLCJhdXRoX3RpbWUiOjE1NjczMTQwMDB9.ObH7oG3NsGaxWnB8rzbLOgAD2I0fr9dyZC81YUrbju3RwC3lRAxqJkbesiSdGKry9OamIhKYwUGpPK0wrBaRJo8UjDjICkhM6lGP23plysemxhDnFK1qjj-NaUaW1yKg14v2lVpQl7glW9LIhFDhpqIf4bILA2wt9-z8Uvi31ETZvGb8PDY2bEvjXR-69-yLuoTNT2skP9loKfz6hHDMQCTWrGA61BMMjkZBLo9UotD9BzN8V7bLrFFT25v6q9N83mWaGLsHntzPIl3EYPOwX0NbE0lXKar59TUqtaTB3uNFHbGjIYi8wuuIp4PV9arpE3YrjWOOmrMurD1KpIyQrQ';
-      const contents = fs.readFileSync(
-        path.resolve(__dirname, './pubkey.pem'),
-        'utf8',
-      );
 
-      const pubKey = KEYUTIL.getKey(contents);
-      const jwkFromKey = KEYUTIL.getJWKFromKey(pubKey);
-
-      jwkFromKey.kid = '1234';
-      jwkFromKey.alg = 'RS256';
-      jwkFromKey.use = 'sig';
-
-      const jwks = {
-        keys: [jwkFromKey],
-      };
-
-      setupFetchMock({jwks});
+      setupFetchMock();
 
       await expect(verify(testJwt)).resolves.toBeUndefined();
     });
-
-    const setupFetchMock = ({
-      domain = BASE_EXPECTATIONS.domain,
-      jwks = getJwks(),
-    } = {}) => {
-      const expectedDiscoveryUri = `https://${domain}/.well-known/openid-configuration`;
-      const expectedJwksUri = `https://${domain}/.well-known/jwks.json`;
-
-      fetchMock.get(expectedDiscoveryUri, {jwks_uri: expectedJwksUri});
-      fetchMock.get(expectedJwksUri, jwks);
-    };
-
-    const getJwks = () => {
-      return {
-        keys: [
-          {
-            kty: 'RSA',
-            n:
-              'st69ml_DI8MhepFSV9o8zjzRFiEst1_1-XJe0ib-g_aMauGTFOqeITdVqWTJMzZsjtwsPFD1CXbmEtI282GBbniJ7XkrZwpjzXangbvJpFE-aBmKeogTq6B94a19H9umCtV7eC55xDmOylXYPFdcVFvolWajdYGywqH8d4Cu_pIB25ELoA78goP4MqweJhnOt4r5jORea2paLXa04ojvglbOGnFec65Y4Hyw2mWGu06f0sxW-LMGzwP_SgbpRDKKnn-W8grguPq63sLexDTBFLyPNCcFQ8wnEQzLCaNNJItu-OFwgwgJhiB3d0et5m3lF2_lEJ2Pwndp0ORlOWcJbQbad',
-            e: 'AQAB',
-            kid: '1234',
-            alg: 'RS256',
-            use: 'sig',
-          },
-        ],
-      };
-    };
   });
 
   describe('token claims verification', () => {
@@ -639,4 +603,21 @@ describe('id token verification tests', () => {
     const options = Object.assign({}, optionsDefaults, optionsOverrides);
     return verifyToken(idToken, options);
   };
+
+  const setupFetchMock = ({
+    domain = BASE_EXPECTATIONS.domain,
+    jwks = getExpectedJwks(),
+  } = {}) => {
+    const expectedDiscoveryUri = `https://${domain}/.well-known/openid-configuration`;
+    const expectedJwksUri = `https://${domain}/.well-known/jwks.json`;
+
+    fetchMock.get(expectedDiscoveryUri, {jwks_uri: expectedJwksUri});
+    fetchMock.get(expectedJwksUri, jwks);
+  };
+
+  const getExpectedJwks = () => {
+    return JSON.parse(
+      fs.readFileSync(path.resolve(__dirname, './jwks.json'), 'utf8'),
+    );
+  };
 });

src/jwt/base64.js

@@ -0,0 +1,32 @@
+/**
+ * Borrowed from IDToken-verifier package
+ * https://github.com/auth0/idtoken-verifier/blob/master/src/helpers/base64.js
+ */
+import base64 from 'base64-js';
+
+export function padding(str) {
+  const paddingLength = 4;
+  const mod = str.length % paddingLength;
+  const pad = paddingLength - mod;
+
+  if (mod === 0) {
+    return str;
+  }
+
+  return str + new Array(1 + pad).join('=');
+}
+
+function byteArrayToHex(raw) {
+  let HEX = '';
+
+  for (let i = 0; i < raw.length; i++) {
+    const _hex = raw[i].toString(16);
+    HEX += _hex.length === 2 ? _hex : '0' + _hex;
+  }
+
+  return HEX;
+}
+
+export function decodeToHEX(str) {
+  return byteArrayToHex(base64.toByteArray(padding(str)));
+}

src/jwt/rsa-verifier.js

@@ -0,0 +1,72 @@
+/*
+Based on the work of Tom Wu
+http://www-cs-students.stanford.edu/~tjw/jsbn/
+http://www-cs-students.stanford.edu/~tjw/jsbn/LICENSE
+*/
+
+import {BigInteger} from 'jsbn';
+import SHA256 from 'crypto-js/sha256';
+
+const digestInfoHead = {
+  sha256: '3031300d060960864801650304020105000420',
+};
+
+const digestAlgs = {
+  sha256: SHA256,
+};
+
+function RSAVerifier(modulus, exp) {
+  this.n = null;
+  this.e = 0;
+
+  if (modulus && modulus.length > 0 && exp && exp.length > 0) {
+    this.n = new BigInteger(modulus, 16);
+    this.e = parseInt(exp, 16);
+  } else {
+    throw new Error('Invalid key data');
+  }
+}
+
+function getAlgorithmFromDigest(hDigestInfo) {
+  for (let algName in digestInfoHead) {
+    const head = digestInfoHead[algName];
+    const len = head.length;
+
+    if (hDigestInfo.substring(0, len) === head) {
+      return {
+        alg: algName,
+        hash: hDigestInfo.substring(len),
+      };
+    }
+  }
+  return [];
+}
+
+RSAVerifier.prototype.verify = function(msg, encodedSignature) {
+  const decodedSignature = encodedSignature.replace(/[^0-9a-f]|[\s\n]]/gi, '');
+
+  const signature = new BigInteger(decodedSignature, 16);
+  if (signature.bitLength() > this.n.bitLength()) {
+    //Signature does not match with the key modulus.
+    return false;
+  }
+
+  const decryptedSignature = signature.modPowInt(this.e, this.n);
+  const digest = decryptedSignature.toString(16).replace(/^1f+00/, '');
+
+  const digestInfo = getAlgorithmFromDigest(digest);
+  if (digestInfo.length === 0) {
+    //Hashing algorithm is not found
+    return false;
+  }
+
+  if (!digestAlgs.hasOwnProperty(digestInfo.alg)) {
+    //Hashing algorithm is not supported
+    return false;
+  }
+
+  const msgHash = digestAlgs[digestInfo.alg](msg).toString();
+  return digestInfo.hash === msgHash;
+};
+
+export default RSAVerifier;

src/jwt/signatureVerifier.js

@@ -1,5 +1,6 @@
 import AuthError from '../auth/authError';
-import {KEYUTIL, KJUR} from 'jsrsasign';
+import RSAVerifier from './rsa-verifier';
+import * as base64 from './base64';
 const jwtDecoder = require('jwt-decode');
 
 const ALLOWED_ALGORITHMS = ['RS256', 'HS256'];
@@ -45,22 +46,28 @@ export const verifySignature = (idToken, options) => {
   }
 
   return getJwk(options.domain, header.kid).then(jwk => {
-    const pubKey = KEYUTIL.getKey(jwk);
-    const signatureValid = KJUR.jws.JWS.verify(idToken, pubKey, ['RS256']);
-
-    if (signatureValid) {
+    const rsaVerifier = rsaVerifierForKey(jwk);
+    const encodedParts = idToken.split('.');
+    const headerAndPayload = encodedParts[0] + '.' + encodedParts[1];
+    const signature = base64.decodeToHEX(encodedParts[2]);
+    if (rsaVerifier.verify(headerAndPayload, signature)) {
       return Promise.resolve(payload);
     }
-
     return Promise.reject(
       idTokenError({
         error: 'invalid_signature',
-        desc: 'Invalid token signature',
+        desc: 'Invalid ID token signature',
       }),
     );
   });
 };
 
+const rsaVerifierForKey = jwk => {
+  const modulus = base64.decodeToHEX(jwk.n);
+  const exponent = base64.decodeToHEX(jwk.e);
+  return new RSAVerifier(modulus, exponent);
+};
+
 const getJwk = (domain, kid) => {
   return getJwksUri(domain)
     .then(uri => fetchJson(uri))

yarn.lock

@@ -1952,6 +1952,11 @@ cross-spawn@^6.0.0:
     shebang-command "^1.2.0"
     which "^1.2.9"
 
+crypto-js@^3.1.9-1:
+  version "3.1.9-1"
+  resolved "https://registry.yarnpkg.com/crypto-js/-/crypto-js-3.1.9-1.tgz#fda19e761fc077e01ffbfdc6e9fdfc59e8806cd8"
+  integrity sha1-/aGedh/Ad+Af+/3G6f38WeiAbNg=
+
 cssom@0.3.x, "cssom@>= 0.3.2 < 0.4.0":
   version "0.3.8"
   resolved "https://registry.yarnpkg.com/cssom/-/cssom-0.3.8.tgz#9f1276f5b2b463f2114d3f2c75250af8c1a36f4a"
@@ -3621,6 +3626,11 @@ js2xmlparser@^4.0.0:
   dependencies:
     xmlcreate "^2.0.0"
 
+jsbn@^1.1.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/jsbn/-/jsbn-1.1.0.tgz#b01307cb29b618a1ed26ec79e911f803c4da0040"
+  integrity sha1-sBMHyym2GKHtJux56RH4A8TaAEA=
+
 jsbn@~0.1.0:
   version "0.1.1"
   resolved "https://registry.yarnpkg.com/jsbn/-/jsbn-0.1.1.tgz#a5e654c2e5a2deb5f201d96cefbca80c0ef2f513"
@@ -3796,11 +3806,6 @@ jsprim@^1.2.2:
     json-schema "0.2.3"
     verror "1.10.0"
 
-jsrsasign@8.0.12:
-  version "8.0.12"
-  resolved "https://registry.yarnpkg.com/jsrsasign/-/jsrsasign-8.0.12.tgz#22abb9656d34a30b9530436720835e89c2e5c316"
-  integrity sha1-Iqu5ZW00owuVMENnIINeicLlwxY=
-
 jwt-decode@^2.2.0:
   version "2.2.0"
   resolved "https://registry.yarnpkg.com/jwt-decode/-/jwt-decode-2.2.0.tgz#7d86bd56679f58ce6a84704a657dd392bba81a79"