File: docs/02-PHP-Library/README.md

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File: docs/02-PHP-Library/README.md
Role: Example script
Content type: text/markdown
Description: Example script
Class: PHP PASeTo
Encrypt and decrypt data with PaSeTO protocol
Author: By
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Date: 9 months ago
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Contents

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How to use the PHP library

The first thing you should know about Paseto is that it tries to accomplish type-safety by wrapping cryptographic keys inside of objects. For example:

<?php
use ParagonIE\Paseto\Keys\{
    AsymmetricSecretKey,
    SymmetricKey    
};

$privateKey = new AsymmetricSecretKey(sodium_crypto_sign_keypair());
$publicKey = $privateKey->getPublicKey();

$sharedKey = new SymmetricKey(random_bytes(32));

You can access the key's internal strings by invoking $key->raw().

No version of the protocol will let you misuse a key by accident. This will generate a TypeError:

<?php
use ParagonIE\Paseto\Protocol\Version2;
use ParagonIE\Paseto\Keys\SymmetricKey;

/
 * @var SymmetricKey $sharedKey
 */
$token = Version2::sign('some arbitrary data', $sharedKey);

Building and Verifying Pasetos

The simplest use-case is to use shared-key authentication to achieve tamper-resistant tokens:

<?php
use ParagonIE\Paseto\Builder;
use ParagonIE\Paseto\Purpose;
use ParagonIE\Paseto\Keys\SymmetricKey;
use ParagonIE\Paseto\Protocol\Version2;

/
 * @var SymmetricKey $sharedKey
 */
$token = Builder::getLocal($sharedKey, new Version2());

$token = (new Builder())
    ->setKey($sharedKey)
    ->setVersion(new Version2())
    ->setPurpose(Purpose::local())
    // Set it to expire in one day
    ->setExpiration(
        (new DateTime())->add(new DateInterval('P01D'))
    )
    // Store arbitrary data
    ->setClaims([
        'example' => 'Hello world',
        'security' => 'Now as easy as PIE'
    ]);
echo $token; // Converts automatically to a string

Decoding tokens

First, you need to define your Parser rules.

  • Which versions of the protocol do you wish to allow? If you're only using v2 in your app, you should specify this.
<?php
use ParagonIE\Paseto\Exception\PasetoException;
use ParagonIE\Paseto\Keys\SymmetricKey;
use ParagonIE\Paseto\Parser;
use ParagonIE\Paseto\Purpose;
use ParagonIE\Paseto\Rules\{
    IssuedBy,
    NotExpired
};
use ParagonIE\Paseto\ProtocolCollection;

/
 * @var string $providedToken
 * @var SymmetricKey $sharedKey
 */
$parser = Parser::getLocal($sharedKey, ProtocolCollection::v2());
// This is the same as:
$parser = (new Parser())
    ->setKey($sharedKey)
    // Adding rules to be checked against the token
    ->addRule(new NotExpired)
    ->addRule(new IssuedBy('issuer defined during creation'))
    ->setPurpose(Purpose::local())
    // Only allow version 2
    ->setAllowedVersions(ProtocolCollection::v2());

try {
    $token = $parser->parse($providedToken);
} catch (PasetoException $ex) {
    /Handle invalid token cases here./
}
var_dump($token instanceof \ParagonIE\Paseto\JsonToken);
// bool(true)

Using the Protocol Directly

Unlike JWT, we don't force you to use JSON. You can store arbitrary binary data in a Paseto, by invoking the Protocol classes directly. This is an advanced usage, of course.

<?php
use ParagonIE\Paseto\Keys\SymmetricKey;
use ParagonIE\Paseto\Protocol\{Version1, Version2};

$key = new SymmetricKey('YELLOW SUBMARINE, BLACK WIZARDRY');
$message = 'This is a signed, non-JSON message.';
$footer = 'key-id:gandalf0';

# Version 1:
$v1Token = Version1::encrypt($message, $key);
var_dump((string) $v1Token);
// string(163) "v1.local.B0VgDOyAtKza1ZCsPzlwQZGTfrpbo1vgzUwCvyxLiSM-gw3TC_KtMqX8woy8BuuE9-pRQNmnTGAru5OmVLzPDnDBHXbd8Sz5rssiTz5TZKLqSyYHsgBzfc53PqsTxLvw09QAy5KBSpKErPX_EfF0Od6-Ig"
var_dump(Version1::decrypt($v1Token, $key));
// string(35) "This is a signed, non-JSON message."

$v1Token = Version1::encrypt($message, $key, $footer);
var_dump((string) $v1Token);
// string(184) "v1.local.vu2ZV_apVDvIhExdenX6rm5w13E3LraRbgN9tabtspSR6KQQt5XdGY5Hho64VRj6Pa6gd-5w5XwmRZbnrxfSVYyvXrVfyDJC7pqQDgae8-MHDg5rZul7kFiH6ExXWx-1hJupWSkRnfQy168PzwS14xiTgw.a2V5LWlkOmdhbmRhbGYw"
var_dump(Version1::decrypt($v1Token, $key, $footer));
// string(35) "This is a signed, non-JSON message."

# Version 2:
$v2Token = Version2::encrypt($message, $key);
var_dump((string) $v2Token);
// string(109) "v2.local.0qOisotef_M2W1gK0b6SiUrO4fkPb24Se0eNJAkALmDvS3IlVu-72birx07hIqU4MYtrCrTJTTElYaWxOyz5Wx8wXh8cQUOF6wOo"
var_dump(Version2::decrypt($v2Token, $key));
// string(35) "This is a signed, non-JSON message."

$v2Token = Version2::encrypt($message, $key, $footer);
var_dump((string) $v2Token);
// string(130) "v2.local.b6ClQBYz-s8k7CC-dEYz2sf3zQFqES4xNUP6K-lzQTRnxVlZFxNnT5I6ouSwYe1d-t9OTnjM9d46MEt__GJvHbNO1wwIfnf1Ear-.a2V5LWlkOmdhbmRhbGYw"
var_dump(Version2::decrypt($v2Token, $key, $footer));
// string(35) "This is a signed, non-JSON message."

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