(PHP Extension) RSA Sign with PKCS8 Encrypted Key

Demonstrates how to load a private key from an encrypted PKCS8 file and create an RSA digital signature (and then verify it).

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->LoadPkcs8EncryptedFile('raul_privateKey.key','a0123456789');

// 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;
}

// This example will sign a string, and receive the signature
// in a hex-encoded string.  Therefore, set the encoding mode
// to "hex":
$rsa->put_EncodingMode('hex');

$strData = 'This is the string to be signed.';

// Sign the string using the sha-1 hash algorithm.
// Other valid choices are "md2" and "md5".
$hexSig = $rsa->signStringENC($strData,'sha-1');

print $hexSig . "\n";

// Now verify with the public key.
// This example shows how to use the public key from 
// a digital certificate (.cer file)
$cert = new CkCert();
$success = $cert->LoadFromFile('raul_publicKey.cer');
if ($success != true) {
    print $cert->lastErrorText() . "\n";
    exit;
}

// pubKey is a CkPublicKey
$pubKey = $cert->ExportPublicKey();

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

$rsa2 = new CkRsa();
$success = $rsa2->ImportPublicKey($pubKeyXml);
if ($success != true) {
    print $rsa2->lastErrorText() . "\n";
    exit;
}

// Verify the signature against the original data:
$rsa2->put_EncodingMode('hex');
$success = $rsa2->VerifyStringENC($strData,'sha-1',$hexSig);
if ($success != true) {
    print $rsa2->lastErrorText() . "\n";
    exit;
}

print 'Signature verified!' . "\n";

// Verify with incorrect data:
$success = $rsa2->VerifyStringENC('something else','sha-1',$hexSig);
if ($success != true) {
    print 'Signature not verified! (which was expected in this case)' . "\n";
}
else {
    print 'Hmmm... that's not right...' . "\n";
}


?>