(PHP Extension) Verify the RSA Signature of a SHA256 Hash

See more RSA Examples

Demonstrates how to verify an RSA signature of a SHA256 hash.

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.

// Let's say you have a file containing the 32-bytes of a SHA256 hash,
// and a file that is an RSA signature of those 32 bytes.
// Here's how you verify using the RSA public key found in a PEM.

$pubKey = new CkPublicKey();
$success = $pubKey->LoadFromFile('rsaPubKey.pem');
if ($success == false) {
    print $pubKey->lastErrorText() . "\n";
    exit;
}

$rsa = new CkRsa();

// Get the public key.
$success = $rsa->ImportPublicKeyObj($pubKey);
if ($success == false) {
    print $rsa->lastErrorText() . "\n";
    exit;
}

// Get the 32-byte SHA256 hash.
$bdHash = new CkBinData();
$success = $bdHash->LoadFile('myHash.sha256');
if ($success == false) {
    print 'Failed to load SHA256 hash.' . "\n";
    exit;
}

// Get the RSA signature to be validated.
$bdSig = new CkBinData();
$success = $bdSig->LoadFile('mySig.sig');
if ($success == false) {
    print 'Failed to load RSA signature.' . "\n";
    exit;
}

// Verify the signature against the SHA256 hash.
$enc = 'base64';
$rsa->put_EncodingMode($enc);
$success = $rsa->VerifyHashENC($bdHash->getEncoded($enc),'sha256',$bdSig->getEncoded($enc));
if ($success == false) {
    print $rsa->lastErrorText() . "\n";
    exit;
}

print 'Signature validated.' . "\n";

?>