(PHP Extension) Verfies an RSA Signature

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Verifies an RSA signature against the original data.

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

<?php

include("chilkat.php");
// Use "chilkat_9_5_0.php" for versions of Chilkat < 10.0.0

// The following data was signed by the following example:
// RSA Sign using a Private Key on a USB Token or Smartcard
$bd = new CkBinData();

for ($i = 0; $i <= 100; $i++) {
    $bd->AppendEncoded('000102030405060708090A0B0C0D0E0F','hex');
}

// Load the signature
$bdSig = new CkBinData();
$success = $bdSig->LoadFile('rsaSignatures/test1.sig');
if ($success == false) {
    print 'Failed to load the RSA signature' . "\n";
    exit;
}

// Get the public key to be used for signature verification.
$pubKey = new CkPublicKey();
$success = $pubKey->LoadFromFile('rsaKeys/chilkat-rsa-2048.pem');
if ($success == false) {
    print $pubKey->lastErrorText() . "\n";
    exit;
}

$rsa = new CkRsa();
$rsa->ImportPublicKeyObj($pubKey);

// Verify the hash of the data against the signature.
// We pass in the original data.  Internally, the hash is generated
// and used to validate the signature.
// Validating the RSA signature means two things:  
// (1) the original data is exactly what was signed, and 
// (2) it was signed by the owner of the RSA private key.
$success = $rsa->VerifyBd($bd,'sha256',$bdSig);

if ($success == false) {
    print $rsa->lastErrorText() . "\n";
    print 'Signature invalid.' . "\n";
}
else {
    print 'Signature valid.' . "\n";
}


?>