(PHP Extension) Verify an RSA Signature Against the Signed Hash

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Demonstrates how to validate an RSA Signature against the hash that was signed.

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

$bd = new CkBinData();

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

$sha256_base64 = $bd->getHash('sha256','base64');
print 'sha256 hash in base64 format: ' . $sha256_base64 . "\n";

$base64_rsa_sig = 'AwF2BbOvL6jA5DwmMAc9n6J2Cc8PI6Rj5W079+aKJcIEtPWRzHor0Bvc3aftGM3Jbgj6SXlIC3M3RYS7UZOnfiHKFNZgbxaNT5WwsWooK42ZkC8DBZl0p7OunBUKd5SciUo+TKilioeUkriN3L1Zl9hwi3HVDVqgVo3XXskwIftSqLSFlepTLTmOWj9Y93dp8J4D9RyLtNgFQBc0WB22tyJTsuY56mLcWe1AMF3LizB9OrbwjynF2u16xWlrJdugccz795fJBUV9aQSD+8S3KeqwQhoi8RK1uhD68aGCyaSpBq0NZ8COAkn7MXaF4POxrAAt8udfHM+PRfSOptcH/w==';

// 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 against the signature.
$rsa->put_EncodingMode('base64');
$success = $rsa->VerifyHashENC($sha256_base64,'sha256',$base64_rsa_sig);

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


?>