(Go) Validate a Google ID Token

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

Chilkat Go Downloads Go Package for Windows, MacOS, Linux, Alpine Linux, Solaris

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    http := chilkat.NewHttp()

    // First get the public key we'll be needing..
    jwkStr := http.QuickGetStr("https://www.googleapis.com/oauth2/v3/certs")
    if http.LastMethodSuccess() == false {
        fmt.Println(http.LastErrorText())
        http.DisposeHttp()
        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"
    // 	}
    //       ]
    //     }

    json := chilkat.NewJsonObject()
    success := 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"
    // }

    jsonToken := chilkat.NewJsonObject()
    success = jsonToken.LoadFile("qa_data/tokens/google_sample_id_token.json")
    if success == false {
        fmt.Println("Failed to load the JSON file...")
        http.DisposeHttp()
        json.DisposeJsonObject()
        jsonToken.DisposeJsonObject()
        return
    }

    // Get the id_token;
    sbIdToken := chilkat.NewStringBuilder()
    success = sbIdToken.Append(*jsonToken.StringOf("id_token"))

    // Get the signature in base64url format.
    // The header + payload remains in sbIdToken.
    sig_b64Url := sbIdToken.GetAfterFinal(".",true)
    headerPlusPayload := sbIdToken.GetAsString()

    fmt.Println(*sig_b64Url)
    fmt.Println(*headerPlusPayload)

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

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

    rsa := chilkat.NewRsa()
    rsa.SetEncodingMode("base64url")

    numKeys := json.SizeOfArray("keys")
    i := 0
    for i < numKeys {
        json.SetI(i)
        jsonKey := json.ObjectOf("keys[i]")
        pubKey := chilkat.NewPublicKey()
        success = pubKey.LoadFromString(*jsonKey.Emit())
        if success == false {
            fmt.Println(pubKey.LastErrorText())
            http.DisposeHttp()
            json.DisposeJsonObject()
            jsonToken.DisposeJsonObject()
            sbIdToken.DisposeStringBuilder()
            rsa.DisposeRsa()
            pubKey.DisposePublicKey()
            return
        }

        fmt.Println(i)
        fmt.Println(*pubKey.GetPem(true))
        jsonKey.DisposeJsonObject()

        success = rsa.ImportPublicKeyObj(pubKey)

        bVerified := rsa.VerifyStringENC(*headerPlusPayload,"sha256",*sig_b64Url)
        fmt.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

    http.DisposeHttp()
    json.DisposeJsonObject()
    jsonToken.DisposeJsonObject()
    sbIdToken.DisposeStringBuilder()
    rsa.DisposeRsa()
    pubKey.DisposePublicKey()