PHP Extension

Generate a CSR with keyUsage, extKeyUsage, and other Extensions

See more CSR Examples

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

PHP Extension

<?php

include("chilkat.php");

$success = false;

// 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 CkEcc();
$prng = new CkPrng();
$privKey = new CkPrivateKey();
$success = $ecc->GenKey('secp256r1',$prng,$privKey);
if ($success == false) {
    print 'Failed to generate a new ECDSA private key.' . "\n";
    exit;
}

$csr = new CkCsr();

// Add common CSR fields:
$csr->put_CommonName('mysubdomain.mydomain.com');
$csr->put_Country('GB');
$csr->put_State('Yorks');
$csr->put_Locality('York');
$csr->put_Company('Internet Widgits Pty Ltd');
$csr->put_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 CkBinData();
$bdTemp->AppendString($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 CkXml();
$xml->put_Tag('set');
$xml->UpdateChildContent('sequence|sequence|oid','1.3.6.1.4.1.311.20.2');
$xml->UpdateAttrAt('sequence|sequence|asnOctets|universal',true,'tag','30');
$xml->UpdateAttrAt('sequence|sequence|asnOctets|universal',true,'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',true,'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 CkPublicKey();
$privKey->ToPublicKey($pubKey);
$bdPubKeyDer = new CkBinData();
$bdPubKeyDer->AppendEncoded($pubKey->getEncoded(true,'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->get_LastMethodSuccess() == false) {
    print $csr->lastErrorText() . "\n";
    exit;
}

print $csrPem . "\n";

?>