(Unicode C) Validate a Google ID Token

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

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#include <C_CkHttpW.h>
#include <C_CkJsonObjectW.h>
#include <C_CkStringBuilderW.h>
#include <C_CkRsaW.h>
#include <C_CkPublicKeyW.h>

void ChilkatSample(void)
    {
    HCkHttpW http;
    const wchar_t *jwkStr;
    HCkJsonObjectW json;
    BOOL success;
    HCkJsonObjectW jsonToken;
    HCkStringBuilderW sbIdToken;
    const wchar_t *sig_b64Url;
    const wchar_t *headerPlusPayload;
    HCkRsaW rsa;
    int numKeys;
    int i;
    HCkJsonObjectW jsonKey;
    HCkPublicKeyW pubKey;
    BOOL bVerified;

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

    http = CkHttpW_Create();

    // First get the public key we'll be needing..
    jwkStr = CkHttpW_quickGetStr(http,L"https://www.googleapis.com/oauth2/v3/certs");
    if (CkHttpW_getLastMethodSuccess(http) == FALSE) {
        wprintf(L"%s\n",CkHttpW_lastErrorText(http));
        CkHttpW_Dispose(http);
        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 = CkJsonObjectW_Create();
    success = CkJsonObjectW_Load(json,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 = CkJsonObjectW_Create();
    success = CkJsonObjectW_LoadFile(jsonToken,L"qa_data/tokens/google_sample_id_token.json");
    if (success == FALSE) {
        wprintf(L"Failed to load the JSON file...\n");
        CkHttpW_Dispose(http);
        CkJsonObjectW_Dispose(json);
        CkJsonObjectW_Dispose(jsonToken);
        return;
    }

    // Get the id_token;
    sbIdToken = CkStringBuilderW_Create();
    success = CkStringBuilderW_Append(sbIdToken,CkJsonObjectW_stringOf(jsonToken,L"id_token"));

    // Get the signature in base64url format.
    // The header + payload remains in sbIdToken.
    sig_b64Url = CkStringBuilderW_getAfterFinal(sbIdToken,L".",TRUE);
    headerPlusPayload = CkStringBuilderW_getAsString(sbIdToken);

    wprintf(L"%s\n",sig_b64Url);
    wprintf(L"%s\n",headerPlusPayload);

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

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

    rsa = CkRsaW_Create();
    CkRsaW_putEncodingMode(rsa,L"base64url");

    numKeys = CkJsonObjectW_SizeOfArray(json,L"keys");
    i = 0;
    while (i < numKeys) {
        CkJsonObjectW_putI(json,i);
        jsonKey = CkJsonObjectW_ObjectOf(json,L"keys[i]");
        pubKey = CkPublicKeyW_Create();
        success = CkPublicKeyW_LoadFromString(pubKey,CkJsonObjectW_emit(jsonKey));
        if (success == FALSE) {
            wprintf(L"%s\n",CkPublicKeyW_lastErrorText(pubKey));
            CkHttpW_Dispose(http);
            CkJsonObjectW_Dispose(json);
            CkJsonObjectW_Dispose(jsonToken);
            CkStringBuilderW_Dispose(sbIdToken);
            CkRsaW_Dispose(rsa);
            CkPublicKeyW_Dispose(pubKey);
            return;
        }

        wprintf(L"%d\n",i);
        wprintf(L"%s\n",CkPublicKeyW_getPem(pubKey,TRUE));
        CkJsonObjectW_Dispose(jsonKey);

        success = CkRsaW_ImportPublicKeyObj(rsa,pubKey);

        bVerified = CkRsaW_VerifyStringENC(rsa,headerPlusPayload,L"sha256",sig_b64Url);
        wprintf(L"bVerified = %d\n",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


    CkHttpW_Dispose(http);
    CkJsonObjectW_Dispose(json);
    CkJsonObjectW_Dispose(jsonToken);
    CkStringBuilderW_Dispose(sbIdToken);
    CkRsaW_Dispose(rsa);
    CkPublicKeyW_Dispose(pubKey);

    }