"bcrypt-nodejs": "0.0.3",
"body-parser": "^1.15.1",
"cors": "^2.7.1",
"express": "~4.1.1",
"firebase": "^3.0.3",
"mongoose": "^4.4.19",
"oauth2orize": "^1.3.0",
"passport": "^0.3.2",
"passport-jwt": "^2.0.0",
"passport-local": "^1.0.0"
"jsonwebtoken": "^7.0.0"

{
        "error": {
        "errors": [
        {
            "domain": "global",
            "reason": "invalid",
            "message": "INVALID_CUSTOM_TOKEN"
        }
        ],
        "code": 400,
        "message": "INVALID_CUSTOM_TOKEN"
    }
}

var token = jwt.sign(
    {
        iss: jwt_config.client_email,
        sub: jwt_config.client_email,
        aud: 'https://identitytoolkit.googleapis.com/google.identity.identitytoolkit.v1.IdentityToolkit',
        iat: iat,
        exp: exp,
        uid: user._id,
        claims: {
            username: user.username,
            user_id: user._id,
            roles: user.role
        }
    },
    jwt_config.private_key,
    {
        algorithm: 'RS256'
    }
);
res.json({success: true, token: token});

var jwt_config = require('../config/Firebase-68824d8xxxxx.json');

firebase.initializeApp(config);
$.ajax({
    type: 'post',
    dataType: 'json',
    url: 'http://ec2-52...compute.amazonaws.com:3000/api/authenticate',
    data: $('#loginForm').serialize(),
    complete: function(result) {
        result = result.responseJSON;
        // console.log(JSON.stringify(result, null, 4));
        var success = result.success;
        if (success) {
            var data = result.token;

            firebase.auth().signInWithCustomToken(data).catch(function(error) {
                // Handle Errors here.
                var errorCode = error.code;
                var data = error.message;
                // ...
            });

        } else {
            var data = result.message;
        }
        $('#token').html(data);
    }
});