(PHP Extension) Create JWS Using Private Key on a Smart Card

See more JSON Web Signatures (JWS) Examples

Creates and validates a JSON Web Signature (JWS) using the private key associated with a certificate on a smart card.

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

<?php

include("chilkat_9_5_0.php");
// This requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// Load the certificate from a smart card.
$cert = new CkCert();
$success = $cert->LoadFromSmartcard('');
if ($success == false) {
    print $cert->lastErrorText() . "\n";
    exit;
}

// Note: Chilkat provides many different ways to load a certificate from a smartcard or USB token,
// such as selecting a certificate if the card contains multiple certificates with private keys,
// or working with lower-level PKCS11 or ScMinidriver API's (both of which Chilkat provides).

// If the associated private key was present on the smartcard, then you can simply
// get it from the Chilkat cert object:
// privKey is a CkPrivateKey
$privKey = $cert->ExportPrivateKey();
if ($cert->get_LastMethodSuccess() == false) {
    print $cert->lastErrorText() . "\n";
    exit;
}

// You can check the key type to make sure it's RSA.
// This will output "rsa" if the key is RSA.
print 'Key type = ' . $privKey->keyType() . "\n";

// Create the JWS Protected Header
$jwsProtHdr = new CkJsonObject();
$jwsProtHdr->AppendString('alg','RS256');

$jws = new CkJws();

// Set the protected header:
$signatureIndex = 0;
$jws->SetProtectedHeader($signatureIndex,$jwsProtHdr);

// Set the RSA key:
$jws->SetPrivateKey($signatureIndex,$privKey);

// Set the payload.
$bIncludeBom = false;
$payloadStr = 'In our village, folks say God crumbles up the old moon into stars.';
$jws->SetPayload($payloadStr,'utf-8',$bIncludeBom);

// Create the JWS
// By default, the compact serialization is used.
$jwsCompact = $jws->createJws();
if ($jws->get_LastMethodSuccess() != true) {
    print $jws->lastErrorText() . "\n";

    exit;
}

print 'JWS: ' . $jwsCompact . "\n";

// sample output:
// JWS: eyJhbGciOiJQUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.TRWhwRo5dMv9-8OzrInfJTwmUGYgjLfHk8lqF072ND-FmLWEBnUTOpY8oJXp8FdWw2SalbdOeNlrtlJjwk4XK8Ql2iJ_2qMCtxsvLPhKBOqFoAF4aBvTOEDVJDxf0DaBSiydEEtfTVV2iwBcjWabu5J2XieR5y7QZQtuHsn7T3qKBvCcCejN3Y2oqAT3qMHvu1fTms1r_91wBn_K7Wjd9UkZ1n02qQcUHJznR_OF2BgN7_KWIDAF9ZS9keoju2NPpPelO4yxa2XUPnehY3G7dHKoCxUEQR4d2Xc5voqDASTVCDqQS4PVOZdvT3Ein6-SanAlCwbWBbkvT8g6-5PImQ

// Now load the JWS, validate, and recover the original text.
$jws2 = new CkJws();

// Load the JWS.
$success = $jws2->LoadJws($jwsCompact);

// rsaPubKey is a CkPublicKey
$rsaPubKey = $privKey->GetPublicKey();

// Set the RSA public key used for validation.
$signatureIndex = 0;
$jws2->SetPublicKey($signatureIndex,$rsaPubKey);

// Validate the 1st (and only) signature at index 0..
$v = $jws2->Validate($signatureIndex);
if ($v < 0) {
    // Perhaps Chilkat was not unlocked or the trial expired..
    print 'Method call failed for some other reason.' . "\n";
    print $jws2->lastErrorText() . "\n";
    exit;
}

if ($v == 0) {
    print 'Invalid signature.  The RSA key was incorrect, the JWS was invalid, or both.' . "\n";
    exit;
}

// If we get here, the signature was validated..
print 'Signature validated.' . "\n";

// Recover the original content:
print $jws2->getPayload('utf-8') . "\n";

// Examine the protected header:
// joseHeader is a CkJsonObject
$joseHeader = $jws2->GetProtectedHeader($signatureIndex);
if ($jws2->get_LastMethodSuccess() != true) {
    print 'No protected header found at the given index.' . "\n";
    exit;
}

$joseHeader->put_EmitCompact(false);

print 'Protected (JOSE) header:' . "\n";
print $joseHeader->emit() . "\n";

// Output:

// 	Signature validated.
// 	In our village, folks say God crumbles up the old moon into stars.
// 	Protected (JOSE) header:
// 	{ 
// 	  "alg": "RS256"
// 	}

?>