The Tor Browser: mobile/android/base/background/fxa/FxAccount10AuthDelegate.java@fc2d59ddac77 (annotated)

mobile/android/base/background/fxa/FxAccount10AuthDelegate.java@fc2d59ddac77 (annotated)

mobile/android/base/background/fxa/FxAccount10AuthDelegate.java

Wed, 31 Dec 2014 07:22:50 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 07:22:50 +0100
branch: TOR_BUG_3246
changeset 4: fc2d59ddac77
permissions: -rw-r--r--

Correct previous dual key logic pending first delivery installment.

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 package org.mozilla.gecko.background.fxa;
 import java.io.UnsupportedEncodingException;
 import java.math.BigInteger;
 import java.security.NoSuchAlgorithmException;
 import org.json.simple.JSONObject;
 import org.mozilla.gecko.sync.ExtendedJSONObject;
 import org.mozilla.gecko.sync.Utils;
 import org.mozilla.gecko.sync.net.SRPConstants;
 public class FxAccount10AuthDelegate implements FxAccountClient10.AuthDelegate {
   // Fixed by protocol.
   protected final BigInteger N;
   protected final BigInteger g;
   protected final int modNLengthBytes;
   // Configured at construction time.
   protected final String email;
   protected final byte[] stretchedPWBytes;
   // Encapsulate state.
   protected static class AuthState {
     protected String srpToken;
     protected String mainSalt;
     protected String srpSalt;
     protected BigInteger x;
     protected BigInteger A;
     protected byte[] Kbytes;
     protected byte[] Mbytes;
   }
   // State should be written exactly once.
   protected AuthState internalAuthState = null;
   public FxAccount10AuthDelegate(String email, byte[] stretchedPWBytes) {
     this.email = email;
     this.stretchedPWBytes = stretchedPWBytes;
     this.N = SRPConstants._2048.N;
     this.g = SRPConstants._2048.g;
     this.modNLengthBytes = SRPConstants._2048.byteLength;
   }
   protected BigInteger generateSecretValue() {
     return Utils.generateBigIntegerLessThan(N);
   }
   public static class FxAccountClientMalformedAuthException extends FxAccountClientException {
     private static final long serialVersionUID = 3585262174699395505L;
     public FxAccountClientMalformedAuthException(String detailMessage) {
       super(detailMessage);
     }
   }
   @SuppressWarnings("unchecked")
   @Override
   public JSONObject getAuthStartBody() throws FxAccountClientException {
     try {
       final JSONObject body = new JSONObject();
       body.put("email", FxAccountUtils.bytes(email));
       return body;
     } catch (UnsupportedEncodingException e) {
       throw new FxAccountClientException(e);
     }
   }
   @Override
   public void onAuthStartResponse(final ExtendedJSONObject body) throws FxAccountClientException {
     if (this.internalAuthState != null) {
       throw new FxAccountClientException("auth must not be written before calling onAuthStartResponse");
     }
     String srpToken = null;
     String srpSalt = null;
     String srpB = null;
     String mainSalt = null;
     try {
       srpToken = body.getString("srpToken");
       if (srpToken == null) {
         throw new FxAccountClientMalformedAuthException("srpToken must be a non-null object");
       }
       ExtendedJSONObject srp = body.getObject("srp");
       if (srp == null) {
         throw new FxAccountClientMalformedAuthException("srp must be a non-null object");
       }
       srpSalt = srp.getString("salt");
       if (srpSalt == null) {
         throw new FxAccountClientMalformedAuthException("srp.salt must not be null");
       }
       srpB = srp.getString("B");
       if (srpB == null) {
         throw new FxAccountClientMalformedAuthException("srp.B must not be null");
       }
       ExtendedJSONObject passwordStretching = body.getObject("passwordStretching");
       if (passwordStretching == null) {
         throw new FxAccountClientMalformedAuthException("passwordStretching must be a non-null object");
       }
       mainSalt = passwordStretching.getString("salt");
       if (mainSalt == null) {
         throw new FxAccountClientMalformedAuthException("srp.passwordStretching.salt must not be null");
       }
       throwIfParametersAreBad(passwordStretching);
       this.internalAuthState = authStateFromParameters(srpToken, mainSalt, srpSalt, srpB, generateSecretValue());
     } catch (FxAccountClientException e) {
       throw e;
     } catch (Exception e) {
       throw new FxAccountClientException(e);
     }
   }
   /**
    * Expect object like:
    * "passwordStretching": {
    *   "type": "PBKDF2/scrypt/PBKDF2/v1",
    *   "PBKDF2_rounds_1": 20000,
    *   "scrypt_N": 65536,
    *   "scrypt_r": 8,
    *   "scrypt_p": 1,
    *   "PBKDF2_rounds_2": 20000,
    *   "salt": "996bc6b1aa63cd69856a2ec81cbf19d5c8a604713362df9ee15c2bf07128efab"
    * }
    * @param params to verify.
    * @throws FxAccountClientMalformedAuthException
    */
   protected void throwIfParametersAreBad(ExtendedJSONObject params) throws FxAccountClientMalformedAuthException {
     if (params == null ||
         params.size() != 7 ||
         params.getString("salt") == null ||
         !("PBKDF2/scrypt/PBKDF2/v1".equals(params.getString("type"))) ||
 != params.getLong("PBKDF2_rounds_1") ||
 != params.getLong("scrypt_N") ||
 != params.getLong("scrypt_r") ||
 != params.getLong("scrypt_p") ||
 != params.getLong("PBKDF2_rounds_2")) {
       throw new FxAccountClientMalformedAuthException("malformed passwordStretching parameters: '" + params.toJSONString() + "'.");
     }
   }
   /**
    * All state is written in this method.
    */
   protected AuthState authStateFromParameters(String srpToken, String mainSalt, String srpSalt, String srpB, BigInteger a) throws NoSuchAlgorithmException, UnsupportedEncodingException {
     AuthState authState = new AuthState();
     authState.srpToken = srpToken;
     authState.mainSalt = mainSalt;
     authState.srpSalt = srpSalt;
     authState.x = FxAccountUtils.srpVerifierLowercaseX(email.getBytes("UTF-8"), this.stretchedPWBytes, Utils.hex2Byte(srpSalt, FxAccountUtils.SALT_LENGTH_BYTES));
     authState.A = g.modPow(a, N);
     String srpA = FxAccountUtils.hexModN(authState.A, N);
     BigInteger B = new BigInteger(srpB, 16);
     byte[] srpABytes = Utils.hex2Byte(srpA, modNLengthBytes);
     byte[] srpBBytes = Utils.hex2Byte(srpB, modNLengthBytes);
     // u = H(pad(A) | pad(B))
     byte[] uBytes = Utils.sha256(Utils.concatAll(
         srpABytes,
         srpBBytes));
     BigInteger u = new BigInteger(Utils.byte2Hex(uBytes, FxAccountUtils.HASH_LENGTH_HEX), 16);
     // S = (B - k*g^x)^(a  u*x) % N
     // k = H(pad(N) | pad(g))
     int byteLength = (N.bitLength() + 7) / 8;
     byte[] kBytes = Utils.sha256(Utils.concatAll(
         Utils.hex2Byte(N.toString(16), byteLength),
         Utils.hex2Byte(g.toString(16), byteLength)));
     BigInteger k = new BigInteger(Utils.byte2Hex(kBytes, FxAccountUtils.HASH_LENGTH_HEX), 16);
     BigInteger base = B.subtract(k.multiply(g.modPow(authState.x, N)).mod(N)).mod(N);
     BigInteger pow = a.add(u.multiply(authState.x));
     BigInteger S = base.modPow(pow, N);
     String srpS = FxAccountUtils.hexModN(S, N);
     byte[] sBytes = Utils.hex2Byte(srpS, modNLengthBytes);
     // M = H(pad(A) | pad(B) | pad(S))
     authState.Mbytes = Utils.sha256(Utils.concatAll(
         srpABytes,
         srpBBytes,
         sBytes));
     // K = H(pad(S))
     authState.Kbytes = Utils.sha256(sBytes);
     return authState;
   }
   @SuppressWarnings("unchecked")
   @Override
   public JSONObject getAuthFinishBody() throws FxAccountClientException {
     if (internalAuthState == null) {
       throw new FxAccountClientException("auth must be successfully written before calling getAuthFinishBody.");
     }
     JSONObject body = new JSONObject();
     body.put("srpToken", internalAuthState.srpToken);
     body.put("A", FxAccountUtils.hexModN(internalAuthState.A, N));
     body.put("M", Utils.byte2Hex(internalAuthState.Mbytes, FxAccountUtils.HASH_LENGTH_HEX));
     return body;
   }
   @Override
   public byte[] getSharedBytes() throws FxAccountClientException {
     if (internalAuthState == null) {
       throw new FxAccountClientException("auth must be successfully finished before calling getSharedBytes.");
     }
     return internalAuthState.Kbytes;
   }
 }

The Tor Browser / annotate

mobile/android/base/background/fxa/FxAccount10AuthDelegate.java@fc2d59ddac77 (annotated)

mobile/android/base/background/fxa/FxAccount10AuthDelegate.java