Java Requires Chilkat v11.0.0+

Validate a Google ID Token

See more OAuth2 Examples

Demonstrates how to verify the signature of a Google id token. Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Http;
import com.chilkatsoft.chilkat2.JsonObject;
import com.chilkatsoft.chilkat2.PublicKey;
import com.chilkatsoft.chilkat2.Rsa;
import com.chilkatsoft.chilkat2.StringBuilder;

public class ChilkatExample {

    public static void main(String[] args) {
        // This example requires the Chilkat API to have been previously unlocked.
        // See Global Unlock Sample for sample code.

        Http http = new Http();

        // First get the public key we'll be needing..
        String jwkStr;
        try {
            jwkStr = http.quickGetStr("https://www.googleapis.com/oauth2/v3/certs");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // We have the following:

        //     {
        //       "keys": [
        //     {
        //       "kid": "e8732db06287515556213b80acbcfd08cfb302a9",
        //       "n": "4RIrO30287Wsq3gqXCMkUYMVAeI3H8...w2mbMNEBQ",
        //       "kty": "RSA",
        //       "e": "AQAB",
        //       "alg": "RS256",
        //       "use": "sig"
        //     },
        //     {
        //       "kid": "8462a71da4f6d611fc0fecf0fc4ba9c37d65e6cd",
        //       "e": "AQAB",
        //       "n": "xT_ngLZNmT5GBtJZeTB...Ft4gK0eoFi0d3l8bcw",
        //       "alg": "RS256",
        //       "use": "sig",
        //       "kty": "RSA"
        //     }
        //       ]
        //     }

        JsonObject json = new JsonObject();
        json.load(jwkStr);

        // -------------------------------------------------

        // Load the following..

        //  {
        //   "access_token": "ya29.a0...0f",
        //   "expires_in": 3599,
        //   "scope": "openid https://www.googleapis.com/auth/userinfo.email",
        //   "token_type": "Bearer",
        //   "id_token": "eyJhb...o5nQ"
        // }

        JsonObject jsonToken = new JsonObject();
        try {
            jsonToken.loadFile("qa_data/tokens/google_sample_id_token.json");
        } catch (ChilkatException e) {
            System.out.println("Failed to load the JSON file...");
            return;
        }

        // Get the id_token;
        StringBuilder sbIdToken = new StringBuilder();
        sbIdToken.append(jsonToken.stringOf("id_token"));

        // Get the signature in base64url format.
        // The header + payload remains in sbIdToken.
        String sig_b64Url = sbIdToken.getAfterFinal(".", true);
        String headerPlusPayload = sbIdToken.getAsString();

        System.out.println(sig_b64Url);
        System.out.println(headerPlusPayload);

        // ---------------------------------------------

        // Try validating with each cert's public key.
        // Hopefully one will be the key that verifies.

        Rsa rsa = new Rsa();
        rsa.setEncodingMode("base64url");

        JsonObject jsonKey = new JsonObject();
        PublicKey pubKey = new PublicKey();

        int numKeys = json.sizeOfArray("keys");
        int i = 0;
        while (i < numKeys) {
            json.setI(i);

            json.objectOf2("keys[i]", jsonKey);

            try {
                pubKey.loadFromString(jsonKey.emit());
            } catch (ChilkatException e) {
                System.out.println(e.getLastErrorText());
                return;
            }

            System.out.println(i);
            System.out.println(pubKey.getPem(true));

            rsa.usePublicKey(pubKey);

            boolean bVerified;
            try {
                rsa.verifyStringENC(headerPlusPayload, "sha256", sig_b64Url);
                bVerified = true;
            } catch (ChilkatException e) {
                bVerified = false;
            }
            System.out.println("bVerified = " + bVerified);

            i = i + 1;
        }

        // The output is:

        // 0
        // -----BEGIN RSA PUBLIC KEY-----
        // MIIBCgKCAQEA4RIrO30287Wsq3gqXCMkUYMVAeI3H8LVE6IXR1krdFeGnZLiGUPw
        // cbkeVpXf3lmJdsStOg+jijces2DZCfPyIBiQuLYfxxmAZE6ErJ0QJFg1stwli2Pz
        // 9ncYhFoqi8pXr7kEzEJBTzX4thuw56ydbGsshSEznPXoerCJOc7UI2+n0wFCWQ4Y
        // LHbh/PrWt4vdadyUUUW/QpQHXQLdD8q/Qwqdj0O9zlJE7R6Elw2E9EqnHyIGu1hm
        // LxhqrTru1M18SUhONYbVskV/BCEdVKs//X96849HorWQDCAgVMWfGsdMVq55FAdJ
        // 680N5UmQDRynIZ4+PeNGN4S9iw2mbMNEBQIDAQAB
        // -----END RSA PUBLIC KEY-----
        //
        // bVerified = True
        // 1
        // -----BEGIN RSA PUBLIC KEY-----
        // MIIBCgKCAQEAxT/ngLZNmT5GBdkLtJZjNeTB+8B5yWgrq/e5eMZ1hrZhcmLK+dSn
        // IkpOPV8/OekV67EnQ7I4II2rcNJnHGrGKZziXO3XN2gtUHE+mBJC99oULSbX/QwB
        // Kz7gC/IBPq9EuxTt6Oq6fPkVQ9DbRIgWJSEGBF/KRaNl3kyAlIZfpY7XgHyJTTv8
        // E7yAcYKPR+36gzdl+ps0sDLKzUuAtZNq8llK0u80z6AtAUIYwWdkEhM9upy6keKI
        // TasIxcsO7M6kZPINUSbh6t5VAm8FuqRmxpgg+9c9/GQSGd89InVypoVzWLQ+wOGg
        // 5G4H6JqIgtj0TRFt4gK0eoFi2U0d3l8bcwIDAQAB
        // -----END RSA PUBLIC KEY-----
        //
        // bVerified = False
    }
}