PHP implementation of PASERK (Platform Agnostic SERialized Keys), a PASETO extension.

v2.1.0 2022-10-11 07:29 UTC

This package is auto-updated.

Last update: 2022-11-11 07:52:18 UTC


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Platform Agnostic SERialized Keys. Requires PHP 7.1 or newer.

PASERK Specification

The PASERK Specification can be found in this repository.


composer require paragonie/paserk

PASERK Library Versions

  • PASERK PHP Version 2
    • Requires PHP 8.1+
    • PASETO versions: v3, v4
      • This means only the corresponding k3 and k4 modes are implemented.
  • PASERK PHP Version 1
    • Requires PHP 7.1+
    • PASETO versions: v1, v2, v3, v4
      • This provides a stable reference implementation for the PASERK specification.


See this directory for the documentation.

Example: Public-key Encryption


use ParagonIE\Paseto\Builder;
use ParagonIE\Paseto\Keys\SymmetricKey;
use ParagonIE\Paseto\Protocol\Version4;
use ParagonIE\Paserk\Operations\Key\SealingPublicKey;
use ParagonIE\Paserk\Types\Seal;

$version = new Version4();

// First, you need a sealing keypair.

// $sealingSecret = ParagonIE\Paserk\Operations\Key\SealingSecretKey::generate();
// $sealingPublic = $sealingSecret->getPublicKey();
// var_dump($sealingSecret->encode(), $sealingPublic->encode());

$sealingPublic = SealingPublicKey::fromEncodedString(
$sealer = new Seal($sealingPublic);

// Generate a random one-time key, which will be encrypted with the public key:
$key = SymmetricKey::generate($version);

// Seal means "public key encryption":
$paserk = $sealer->encode($key);

// Now let's associate this PASERK with a PASETO that uses the local key:
$paseto = Builder::getLocal($key, $version)
    ->with('test', 'readme')
        (new DateTime('NOW'))
            ->add(new DateInterval('P01D'))
    ->withFooterArray(['kid' => $sealer->id($key)])

var_dump($paserk, $paseto);


use ParagonIE\Paseto\Protocol\Version4;
use ParagonIE\Paserk\Operations\Key\SealingSecretKey;
use ParagonIE\Paserk\Types\Lid;
use ParagonIE\Paserk\Types\Seal;
use ParagonIE\Paseto\Parser as PasetoParser;
use ParagonIE\Paseto\ProtocolCollection;

$version = new Version4();

// From previous example:
$paserk = "k4.seal.F2qE4x0JfqT7JYhOB7S12SikvLaRuEpxRkgxxHfh4hVpE1JfwIDnreuhs9v5gjoBl3WTVjdIz6NkwQdqRoS2EDc3yGvdf_Da4K1xUSJ8IVTn4HQeol5ruYwjQlA_Ph4N";
$paseto = "v4.local.hYG-BfpTTM3bb-xZ-q5-w77XGayS4WA8kA5R5ZL85u3nzgrWba5NdqgIouFn71CJyGAff1eloirzz3sWRdVXnDeSIYxXDIerNkbLI5ALn24JehhSLKrv8R2-yhfo_XZF9XEASXtwrOyMNjeEAan5kqO6Dg.eyJraWQiOiJrNC5saWQueDAycGJDRmhxU1Q4endnbEJyR3VqWE9LYU5kRkJjY1dsTFFRN0pzcGlZM18ifQ";

// Keys for unsealing:
$sealingSecret = SealingSecretKey::fromEncodedString(
$sealingPublic = $sealingSecret->getPublicKey();

// Unwrap the sytmmetric key for `v4.local.` tokens.
$sealer = new Seal($sealingPublic, $sealingSecret);
$unwrapped = $sealer->decode($paserk);

// Parse the PASETO
$parsed = PasetoParser::getLocal($unwrapped, ProtocolCollection::v4())

// Get the claims from the parsed and validated token:
array(2) {
  string(6) "readme"
  string(25) "2038-01-19T03:14:08+00:00"

// Observe the Key ID is the same as the value stored in the footer.
var_dump(Lid::encode($version, $paserk));
string(51) "k4.lid.x02pbCFhqST8zwglBrGujXOKaNdFBccWlLQQ7JspiY3_"
string(51) "k4.lid.x02pbCFhqST8zwglBrGujXOKaNdFBccWlLQQ7JspiY3_"

PASERK Feature Coverage