(PHP Extension) Trust Specific Root CA Certificates

Demonstrates how to trust specific root CA certificates and none others.

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

<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

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

// This example will trust the Amazon root CA certificates provided at 
// https://www.amazontrust.com/repository/

// I've previously downloaded the root CA certificates to DER format.
// Add each to the Chilkat TrustedRoots singleton object.

$tRoots = new CkTrustedRoots();

$caCert = new CkCert();
$success = $caCert->LoadFromFile('qa_data/certs/aws_root_ca/AmazonRootCA1.cer');
if ($success == false) {
    print $caCert->lastErrorText() . "\n";
    exit;
}

$success = $tRoots->AddCert($caCert);

// Continue with the others.
// For brevity, we're not checking return values for success/failure.
$success = $caCert->LoadFromFile('qa_data/certs/aws_root_ca/AmazonRootCA2.cer');
$success = $tRoots->AddCert($caCert);

$success = $caCert->LoadFromFile('qa_data/certs/aws_root_ca/AmazonRootCA3.cer');
$success = $tRoots->AddCert($caCert);

$success = $caCert->LoadFromFile('qa_data/certs/aws_root_ca/AmazonRootCA4.cer');
$success = $tRoots->AddCert($caCert);

$success = $caCert->LoadFromFile('qa_data/certs/aws_root_ca/SFSRootCAG2.cer');
$success = $tRoots->AddCert($caCert);

// Indicate we don't want to automatically trust the operating system's installed root CA certificates.
// On a Windows operating system, this would be the registry-based CA certificate stores. 
// On a Linux system, this could be /etc/ssl/certs/ca-certificates.crt, if it exists.
$tRoots->put_TrustSystemCaRoots(false);

// Activate the trusted roots object.
// Once activated, all Chilkat objects that use TLS connections (HTTP, REST, Socket, MailMan, IMAP, FTP, etc.)
// will fail the TLS handshake if the server certificate is not verified and rooted with one of our explicitly trusted root certificates.
$success = $tRoots->Activate();

$http = new CkHttp();

// Note: We also need to explicitly indicate that server certificates are to be verified.
$http->put_RequireSslCertVerify(true);

// For example, the following should fail because www.chilkatsoft.com's server certificate is not rooted in one of the explicitly trusted root CA certs.
$success = $http->Download('https://www.chilkatsoft.com/helloWorld.txt','qa_output/helloWorld.txt');
if ($success != true) {
    // The above Download should fail.
    print $http->lastErrorText() . "\n";

    // There should be a message in the LastErrorText indicating that we were "Unable to build certificate chain to root.."
}

// However, we should be able to make TLS connections to good.sca1a.amazontrust.com
$success = $http->Download('https://good.sca1a.amazontrust.com/','qa_output/valid.html');
if ($success != true) {
    print $http->lastErrorText() . "\n";
    exit;
}

// We can still examine the LastErrorText and we'll find this message within:  
// "The public key was successfully validated against the public key of the explicitly trusted root cert."
print $http->lastErrorText() . "\n";

print 'Success!' . "\n";

?>