(PHP Extension) Duplicate openssl dgst -md5 -sign myKey.pem something.txt | openssl enc -base64 -A

Demonstrates how to duplicate the creation of an RSA signature produced by this OpenSSL command:

openssl dgst -md5 -sign myKey.pem something.txt | openssl enc -base64 -A

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.

$pkey = new CkPrivateKey();

// Load the private key from an RSA PEM file:
$success = $pkey->LoadPemFile('myKey.pem');

// Get the private key in XML format:
$pkeyXml = $pkey->getXml();

$rsa = new CkRsa();

// Import the private key into the RSA component:
$success = $rsa->ImportPrivateKey($pkeyXml);
if ($success != true) {
    print $rsa->lastErrorText() . "\n";
    exit;
}

// OpenSSL uses BigEndian byte ordering:
$rsa->put_LittleEndian(false);

// The resulting signature will be a Base64 string:
$rsa->put_EncodingMode('base64');

// For simplicity, we're not loading
// the data to be signed from a file.  We are instead simply
// using a literal string value.  
$strData = 'This is the text to be signed.';

// Hash the input using MD5, and then sign the hash:
// Other valid hash algorithm choices are "md2" and "sha-1".
$base64Sig = $rsa->signStringENC($strData,'md5');

print $base64Sig . "\n";

print 'Success!' . "\n";

?>