(PHP Extension) Get Google API Access Token using JSON Private Key using NIST Time Server Date/Time

Demonstrates how to get a Google API access token using a JSON service account private key, using the NIST time server date/time rather than the local system date/time.

Chilkat PHP Downloads PHP Extension for Windows, Linux, MacOS, Alpine Linux, Solaris

<?php

include("chilkat_9_5_0.php");
// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// First, let's get the current date/time from time-c.nist.gov
$socket = new CkSocket();

// Connect to an NIST time server and read the current date/time
$maxWaitMs = 8000;
$useTls = false;
$success = $socket->Connect('time-c.nist.gov',37,$useTls,$maxWaitMs);
if ($success != true) {
    print $socket->lastErrorText() . "\n";
    exit;
}

// The time server will send a big-endian 32-bit integer representing
// the number of seconds since since 00:00 (midnight) 1 January 1900 GMT.
// The ReceiveInt32 method will receive a 4-byte integer, but returns
// true or false to indicate success.  If successful, the integer
// is obtained via the ReceivedInt property.
$bigEndian = true;
$success = $socket->ReceiveInt32($bigEndian);
if ($success != true) {
    print $socket->lastErrorText() . "\n";
    exit;
}

$dt = new CkDateTime();
$dt->SetFromNtpTime($socket->get_ReceivedInt());

// Show the current local date/time
$bLocalTime = true;
print 'Current local date/time: ' . $dt->getAsRfc822($bLocalTime) . "\n";

$maxWaitMs = 10;
$socket->Close($maxWaitMs);

// ------------------------------------------------------------------------
// OK, we have the current date/time.  We'll use it to set the IAT property
// in the code below.

// First load the JSON key into a string.
$fac = new CkFileAccess();
$jsonKey = $fac->readEntireTextFile('qa_data/googleApi/ChilkatTest-ab2ecd52ef98.json','utf-8');
if ($fac->get_LastMethodSuccess() != true) {
    print $fac->lastErrorText() . "\n";
    exit;
}

// A JSON private key should look like this:

// 	{
// 	  "type": "service_account",
// 	  "project_id": "chilkattest-1350",
// 	  "private_key_id": "fa2e36ee26986eab628b59868af8bec1d1c64c38",
// 	  "private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvgIjFa...28N64N2n1E4FYzBZjSdy\n-----END PRIVATE KEY-----\n",
// 	  "client_email": "598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a@developer.gserviceaccount.com",
// 	  "client_id": "598922945226-00rb0ppfg0snd9jo7bhvd4v17jtj2d3a.apps.googleusercontent.com",
// 	  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
// 	  "token_uri": "https://accounts.google.com/o/oauth2/token",
// 	  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
// 	  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a%40developer.gserviceaccount.com"
// 	}

$gAuth = new CkAuthGoogle();
$gAuth->put_JsonKey($jsonKey);

// Choose a scope.
$gAuth->put_Scope('https://www.googleapis.com/auth/cloud-platform');

// Request an access token that is valid for this many seconds.
$gAuth->put_ExpireNumSeconds(3600);

// If the application is requesting delegated access:
// The email address of the user for which the application is requesting delegated access,
// then set the email address here. (Otherwise leave it empty.)
$gAuth->put_SubEmailAddress('');

// ------------------------------------------------------------------------
// Set the IAT using the date/time from the NIST time server.
$unixTime = $dt->GetAsUnixTime(false);
print 'unixTime = ' . $unixTime . "\n";
$gAuth->put_Iat($unixTime);

// Connect to www.googleapis.com using TLS (TLS 1.2 is the default.)
// The Chilkat socket object is used so that the connection can be established
// through proxies or an SSH tunnel if desired.
$tlsSock = new CkSocket();
$success = $tlsSock->Connect('www.googleapis.com',443,true,5000);
if ($success != true) {
    print $tlsSock->lastErrorText() . "\n";
    exit;
}

// Send the request to obtain the access token.
$success = $gAuth->ObtainAccessToken($tlsSock);
if ($success != true) {
    print $gAuth->lastErrorText() . "\n";
    exit;
}

// Examine the access token:
print 'Access Token: ' . $gAuth->accessToken() . "\n";

?>