SigningSerializer.php

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<?php

declare(strict_types=1);

namespace ILIAS\FileDelivery\Token;

use ILIAS\FileDelivery\Token\Serializer\Serializer;
use ILIAS\FileDelivery\Token\Signer\Payload\Payload;
use ILIAS\FileDelivery\Token\Signer\Payload\StructuredPayload;
use ILIAS\FileDelivery\Token\Compression\GZipCompression;
use ILIAS\FileDelivery\Token\Compression\Compression;
use ILIAS\FileDelivery\Token\Transport\Transport;
use ILIAS\FileDelivery\Token\Signer\KeyRotatingSigner;
use ILIAS\FileDelivery\Token\Signer\Salt\Salt;

final class SigningSerializer
{
    private const SEPARATOR = '<<>>';

    public function __construct(
        private KeyRotatingSigner $signer,
        private Serializer $serializer,
        private Compression $compression,
        private Transport $transport
    ) {
    }

    public function sign(Payload $payload, Salt $salt): string
    {
        // serialize payload
        $serialized_payload = $this->serializer->serializePayload($payload->get());
        $serialized_validity = $this->serializer->serializeValidity($payload->until());
        $signable_payload = $serialized_payload . self::SEPARATOR . $serialized_validity;

        // sign payload
        $signature = $this->signer->sign($signable_payload, $salt);

        $signed_payload = $signable_payload . self::SEPARATOR . $signature;

        $compressed_payload = $this->compression->compress($signed_payload);

        $prepare_for_transport = $this->transport->prepareForTransport($compressed_payload);

        return $prepare_for_transport;
    }

    public function verify(string $data, Salt $salt): ?Payload
    {
        // decompress payload
        try {
            $decompressed_payload = $this->compression->decompress(
                $this->transport->readFromTransport($data)
            );
        } catch (\Throwable $e) {
            return null;
        }

        $split_data = explode(self::SEPARATOR, $decompressed_payload);
        $serialized_payload = $split_data[0] ?? '';
        $validity = $split_data[1] ?? '';
        $signature = $split_data[2] ?? '';

        $payload_with_validity = $serialized_payload . self::SEPARATOR . $validity;

        if ($this->signer->verify($payload_with_validity, $signature, (int) $validity, $salt) === false) {
            return null;
        }

        return new StructuredPayload($this->serializer->unserializePayload($serialized_payload));
    }
}