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Branca Tokens for PHP

Authenticated and encrypted API tokens using modern crypto.

What?

Branca is a secure easy to use token format which makes it hard to shoot yourself in the foot. It uses IETF XChaCha20-Poly1305 AEAD symmetric encryption to create encrypted and tamperproof tokens. Payload itself is an arbitrary sequence of bytes. You can use for example a JSON object, plain text string or even binary data serialized by MessagePack or Protocol Buffers.

It is possible to use Branca as an alternative to JWT. There is also an authentication middleware for frameworks which support PSR-7 doublepass or PSR-15 standards.

Install

Install the library using Composer.

$ composer require tuupola/branca

This branch requires PHP 7.2 or up. The older 1.x branch supports also PHP 5.6, 7.0 and 7.1.

$ composer require "tuupola/branca:^1.0"

Usage

Token payload can be any arbitrary data such as string containing an email address. You also must provide a 32 byte secret key. The key is used for encrypting the payload.

use Branca\Branca;

$key = random_bytes(32);
$branca = new Branca($key);

$payload = "tuupola@appelsiini.net";
$token = $branca->encode($payload);
/* hGgg0dPSseaUPZqGloWlDGb2i8hb6iamFBIQaatgYDRhEuaXyByaX0nzmyQk1WYAuSBEMWpB20Z1dENLFItwf1 */

$decoded = $branca->decode($token);
/* tuupola@appelsiini.net */

Sometimes you might prefer JSON.

use Branca\Branca;

$key = random_bytes(32);
$branca = new Branca($key);

$payload = json_encode(["scope" => ["read", "write", "delete"]]);
$token = $branca->encode($payload);

/*
5R7p5pC1gU5kfVuBUzhl43Ndh4HLT9fxAHrhN1zNRivTuehY8zYYzrVZ8C6d6VcNLfCk3EUgBwwW6kIk0wm32O34OFIYz5LnOIezwcV2Xsfc
*/

$decoded = $branca->decode($token);
$array = json_decode($decoded, true);

/*
Array
(
    [scope] => Array
        (
            [0] => read
            [1] => write
            [2] => delete
        )

)
*/

You can keep the token size small by using a space efficient serialization method such as MessagePack or Protocol Buffers.

use Branca\Branca;
use MessagePack\MessagePack;
use MessagePack\Packer;
use MessagePack\BufferUnpacker;

$key = random_bytes(32);
$branca = new Branca($key);

$payload = (new Packer)->pack(["scope" => ["read", "write", "delete"]]);
$token = $branca->encode($payload);

/*
3iJt0CjqTRh3FGuAf0DHEmhULFIbPVInjguWIkmyCm7RMps5BMJZKa1KwZMN0z58IpPeCxdjoTdkurn9pl0YNrxAQfg3deP0
*/

$decoded = $branca->decode($token);
$unpacked = (new BufferUnpacker($decoded))->unpack();
print_r($unpacked);

/*
Array
(
    [scope] => Array
        (
            [0] => read
            [1] => write
            [2] => delete
        )

)
*/

Timestamp

Branca token includes a timestamp when it was created. When decoding you can optionally pass a ttl parameter. Value is passed in seconds. Below example throws en exception if token is older than 60 minutes.

use Branca\Branca;

$key = hex2bin("73757065727365637265746b6579796f7573686f756c646e6f74636f6d6d6974");
$branca = new Branca($key);

$token = "1jJDJOEeG2FutA8g7NAOHK4Mh5RIE8jtbXd63uYbrFDSR06dtQl9o2gZYhBa36nZHXVfiGFz";

print $branca->timestamp($token); /* 123206400 */

try {
    $decoded = $branca->decode($token, 3600);
} catch (RuntimeException $exception) {
    print $exception->getMessage(); /* Token is expired */
}

Testing

You can run tests either manually or automatically on every code change. Automatic tests require entr to work.

$ make test

$ brew install entr
$ make watch

Contributing

Please see CONTRIBUTING for details.

Security

If you discover any security related issues, please email tuupola@appelsiini.net instead of using the issue tracker.

License

The MIT License (MIT). Please see License File for more information.