PHP ActiveX Requires Chilkat v11.0.0+
Generate a CSR with keyUsage, extKeyUsage, and other Extensions

Demonstrates how to generate a CSR containing a 1.2.840.113549.1.9.14 extensionRequest with the following extensions:
1.3.6.1.4.1.311.20.2 enrollCerttypeExtension
2.5.29.15 keyUsage
2.5.29.37 extKeyUsage
2.5.29.14 subjectKeyIdentifier
Chilkat PHP ActiveX Downloads

PHP ActiveX
<?php

$success = 0;

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

//  This example will generate a secp256r1 ECDSA key for the CSR.
$ecc = new COM("Chilkat.Ecc");
$prng = new COM("Chilkat.Prng");
$privKey = new COM("Chilkat.PrivateKey");
$success = $ecc->GenKey('secp256r1',$prng,$privKey);
if ($success == 0) {
    print 'Failed to generate a new ECDSA private key.' . "\n";
    exit;
}

$csr = new COM("Chilkat.Csr");

//  Add common CSR fields:
$csr->CommonName = 'mysubdomain.mydomain.com';
$csr->Country = 'GB';
$csr->State = 'Yorks';
$csr->Locality = 'York';
$csr->Company = 'Internet Widgits Pty Ltd';
$csr->EmailAddress = 'support@mydomain.com';

//  Add the following 1.2.840.113549.1.9.14 extensionRequest
//  Note: The easiest way to know the content and format of the XML to be added is to examine
//  a pre-existing CSR with the same desired extensionRequest.  You can use Chilkat to
//  get the extensionRequest from an existing CSR. 

//  Here is a sample extension request:

//  <?xml version="1.0" encoding="utf-8"?>
//  <set>
//      <sequence>
//          <sequence>
//              <oid>1.3.6.1.4.1.311.20.2</oid>
//              <asnOctets>
//                  <universal tag="30" constructed="0">AEUAbgBkAEUAbgB0AGkAdAB5AEMAbABpAGUAbgB0AEEAdQB0AGgAQwBlAHIAdABpAGYAaQBjAGEAdABl
//  AF8AQwBTAFIAUABhAHMAcwB0AGgAcgBvAHUAZwBoAC8AVgAx</universal>
//              </asnOctets>
//          </sequence>
//          <sequence>
//              <oid>2.5.29.15</oid>
//              <bool>1</bool>
//              <asnOctets>
//                  <bits n="3">A0</bits>
//              </asnOctets>
//          </sequence>
//          <sequence>
//              <oid>2.5.29.37</oid>
//              <asnOctets>
//                  <sequence>
//                      <oid>1.3.6.1.5.5.7.3.3</oid>
//                  </sequence>
//              </asnOctets>
//          </sequence>
//          <sequence>
//              <oid>2.5.29.14</oid>
//              <asnOctets>
//                  <octets>MCzBMQAViXBz8IDt8LsgmJxJ4Xg=</octets>
//              </asnOctets>
//          </sequence>
//      </sequence>
//  </set>

//  Use this online tool to generate code from sample XML: 
//  Generate Code to Create XML

//  A few notes:
//  The string "AEUAbgBkAEUAbgB0AGkAdAB5AEMAbABpAGUAbgB0AEEAdQB0AGgAQwBlAHIAdABpAGYAaQBjAGEAdABlAF8AQwBTAFIAUABhAHMAcwB0AGgAcgBvAHUAZwBoAC8AVgAx"
//  is the base64 encoding of the utf-16be byte representation of the string "EndEntityClientAuthCertificate_CSRPassthrough/V1"

$s = 'EndEntityClientAuthCertificate_CSRPassthrough/V1';
$bdTemp = new COM("Chilkat.BinData");
$bdTemp->AppendString($s,'utf-16be');
$s_base64_utf16be = $bdTemp->getEncoded('base64');
//  The string should be "AEUA....."
print $s_base64_utf16be . "\n";

//  Here's the code to generate the above extension request.

$xml = new COM("Chilkat.Xml");
$xml->Tag = 'set';
$xml->UpdateChildContent('sequence|sequence|oid','1.3.6.1.4.1.311.20.2');
$xml->UpdateAttrAt('sequence|sequence|asnOctets|universal',1,'tag','30');
$xml->UpdateAttrAt('sequence|sequence|asnOctets|universal',1,'constructed','0');
$xml->UpdateChildContent('sequence|sequence|asnOctets|universal',$s_base64_utf16be);
$xml->UpdateChildContent('sequence|sequence[1]|oid','2.5.29.15');
$xml->UpdateChildContent('sequence|sequence[1]|bool','1');
$xml->UpdateAttrAt('sequence|sequence[1]|asnOctets|bits',1,'n','3');
//  A0 is hex for decimal 160.
$xml->UpdateChildContent('sequence|sequence[1]|asnOctets|bits','A0');
$xml->UpdateChildContent('sequence|sequence[2]|oid','2.5.29.37');
$xml->UpdateChildContent('sequence|sequence[2]|asnOctets|sequence|oid','1.3.6.1.5.5.7.3.3');

//  This is the subjectKeyIdentifier extension.
//  The string "MCzBMQAViXBz8IDt8LsgmJxJ4Xg=" is base64 that decodes to 20 bytes, which is a SHA1 hash.
//  This is simply a hash of the DER of the public key.

$pubKey = new COM("Chilkat.PublicKey");
$privKey->ToPublicKey($pubKey);
$bdPubKeyDer = new COM("Chilkat.BinData");
$bdPubKeyDer->AppendEncoded($pubKey->getEncoded(1,'base64'),'base64');
$ski = $bdPubKeyDer->getHash('sha1','base64');

$xml->UpdateChildContent('sequence|sequence[3]|oid','2.5.29.14');
$xml->UpdateChildContent('sequence|sequence[3]|asnOctets|octets',$ski);

//  Add the extension request to the CSR
$csr->SetExtensionRequest($xml);

//  Generate the CSR with the extension request
$csrPem = $csr->genCsrPem($privKey);
if ($csr->LastMethodSuccess == 0) {
    print $csr->LastErrorText . "\n";
    exit;
}

print $csrPem . "\n";

?>