Google OAuth2 JWT token verification exception

Question

I'm facing OAuth2 JWT token verification exception last hour (so no one can access my application):

java.security.SignatureException: Signature length not correct: got 256 but was expecting 128. I'm using google-http-client 1.20.0 and Java 1.7.0. Same configuration worked so far - any ideas?

Stacktrace

java.security.SignatureException: Signature length not correct: got 256 but was expecting 128
    at sun.security.rsa.RSASignature.engineVerify(Unknown Source) ~[na:1.7.0_45]
    at java.security.Signature$Delegate.engineVerify(Unknown Source) ~[na:1.7.0_45]
    at java.security.Signature.verify(Unknown Source) ~[na:1.7.0_45]
    at com.google.api.client.util.SecurityUtils.verify(SecurityUtils.java:164) ~[google-http-client-1.20.0.jar:1.20.0]

Answer 1

Same problem here, I added the source code of GoogleIdTokenVerifier to my project and changed the method:

 public boolean verify(GoogleIdToken googleIdToken) throws GeneralSecurityException, IOException {
    // check the payload
    if (!super.verify(googleIdToken)) {
      return false;
    }
    // verify signature
    for (PublicKey publicKey : publicKeys.getPublicKeys()) {
      try {
        if (googleIdToken.verifySignature(publicKey)) {
            return true;
          }
    } catch (Exception e) {
        System.err.println("Verify Token:" + e);
    }
    }
    return false;
  }

just handle the exception, the second certificate works fine.

Edit: you can subclass as Erik-z suggested if you want to make it more clean:

Edit 2: I can't make it work using the code below, I will stick to the ugly hack above.

package com.my.project.package;

import java.io.IOException;
import java.security.GeneralSecurityException;
import java.security.PublicKey;

import com.google.api.client.auth.openidconnect.IdTokenVerifier;
import com.google.api.client.googleapis.auth.oauth2.GoogleIdToken;
import com.google.api.client.googleapis.auth.oauth2.GoogleIdTokenVerifier;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.JsonFactory;

// Remember to remove this class later by making it deprecated
@Deprecated
public class GoogleIdTokenVerifier2 extends GoogleIdTokenVerifier {

    // Add constructors as needed
    public GoogleIdTokenVerifier2(HttpTransport transport, JsonFactory jsonFactory) {
        super(transport, jsonFactory);
    }

    @Override
    public boolean verify(GoogleIdToken googleIdToken) throws GeneralSecurityException, IOException {
        // check the payload
        if (!((IdTokenVerifier)this).verify(googleIdToken)) {
            return false;
        }
        // verify signature
        for (PublicKey publicKey : getPublicKeysManager().getPublicKeys()) {
            try {
                if (googleIdToken.verifySignature(publicKey)) {
                    return true;
                }
            } catch (Exception e) {
                System.err.println("Verify Token:" + e);
            }
        }
        return false;
    }
}

Answer 2

Don't think it's the final solution but a temporary work-around which definitely works is to change the audience of the verifier to the tokenId.

GoogleIdTokenVerifier verifier = new GoogleIdTokenVerifier.Builder(transport, jsonFactory).setAudience(Arrays.asList(clientId)).build();

to

GoogleIdTokenVerifier verifier = new GoogleIdTokenVerifier.Builder(transport, jsonFactory)
                    .setAudience(Arrays.asList(tokenResponse.getIdToken())).build();