Jose\Encrypter

Complexity

Total Complexity

47

Size/Duplication

Total Lines	529
Duplicated Lines	0 %

Coupling/Cohesion

Components	1
Dependencies	18

Importance

Changes	37
Bugs	18	Features	4

18 Methods

Rating	Name	Duplication	Size	Complexity
A	__construct()	0	12	2
B	encrypt()	0	68	4
B	processRecipient()	0	51	4
B	determineCEK()	0	31	5
B	getKeyManagementMode()	0	28	3
B	getCompressionMethod()	0	35	6
A	getContentEncryptionAlgorithm()	0	23	3
B	encryptJWE()	0	31	3
A	checkKeys()	0	9	2
B	areKeyManagementModesCompatible()	0	32	2
A	preparePayload()	0	14	3
A	getEncryptedKey()	0	12	4
A	getEncryptedKeyFromKeyAgreementAndKeyWrappingAlgorithm()	0	6	1
A	getEncryptedKeyFromKeyEncryptionAlgorithm()	0	9	1
A	getEncryptedKeyFromKeyWrappingAlgorithm()	0	9	1
A	findKeyEncryptionAlgorithm()	0	9	1
A	createCEK()	0	4	1
A	createIV()	0	4	1

<?php

/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2014-2016 Spomky-Labs
 *
 * This software may be modified and distributed under the terms
 * of the MIT license.  See the LICENSE file for details.
 */

namespace Jose;

use Assert\Assertion;
use Base64Url\Base64Url;
use Jose\Algorithm\ContentEncryptionAlgorithmInterface;
use Jose\Algorithm\JWAManagerInterface;
use Jose\Algorithm\KeyEncryption\KeyAgreementWrappingInterface;
use Jose\Algorithm\KeyEncryption\KeyEncryptionInterface;
use Jose\Algorithm\KeyEncryption\KeyWrappingInterface;
use Jose\Algorithm\KeyEncryptionAlgorithmInterface;
use Jose\Behaviour\HasCompressionManager;
use Jose\Behaviour\HasJWAManager;
use Jose\Behaviour\HasKeyChecker;
use Jose\Behaviour\HasLogger;
use Jose\Compression\CompressionInterface;
use Jose\Compression\CompressionManagerInterface;
use Jose\Object\JWEInterface;
use Jose\Object\JWKInterface;
use Jose\Object\Recipient;
use Jose\Object\RecipientInterface;
use Psr\Log\LoggerInterface;
use Psr\Log\LogLevel;

final class Encrypter implements EncrypterInterface
{
    use HasKeyChecker;
    use HasJWAManager;
    use HasCompressionManager;
    use HasLogger;

    /**
     * Encrypter constructor.
     *
     * @param \Jose\Algorithm\JWAManagerInterface           $jwa_manager
     * @param \Jose\Compression\CompressionManagerInterface $compression_manager
     * @param \Psr\Log\LoggerInterface|null                 $logger
     */
    public function __construct(
        JWAManagerInterface $jwa_manager,
        CompressionManagerInterface $compression_manager,
        LoggerInterface $logger = null
    ) {
        $this->setJWAManager($jwa_manager);
        $this->setCompressionManager($compression_manager);

        if (null !== $logger) {
            $this->setLogger($logger);
        }
    }

    /**
     * {@inheritdoc}
     */
    public function encrypt(JWEInterface &$jwe)
    {
        $this->log(LogLevel::INFO, 'Trying to encrypt the JWE object', ['jwe' => $jwe]);
        Assertion::false($jwe->isEncrypted(), 'The JWE is already encrypted.');
        Assertion::greaterThan($jwe->countRecipients(), 0, 'The JWE does not contain recipient.');

        // Content Encryption Algorithm
        $this->log(LogLevel::DEBUG, 'Trying to find the content encryption algorithm');
        $content_encryption_algorithm = $this->getContentEncryptionAlgorithm($jwe);
        $this->log(LogLevel::DEBUG, 'The content encryption algorithm has been found', ['content_encryption_algorithm', $content_encryption_algorithm]);

        // Compression Method
        $this->log(LogLevel::DEBUG, 'Trying to find the compression method (if needed)');
        $compression_method = $this->getCompressionMethod($jwe);
        $this->log(LogLevel::DEBUG, 'The compression method search is finished', ['compression_method', $compression_method]);

        // Key Management Mode
        $this->log(LogLevel::DEBUG, 'Trying to find the key management mode');
        $key_management_mode = $this->getKeyManagementMode($jwe);
        $this->log(LogLevel::DEBUG, 'The key management mode has been found', ['key_management_mode', $key_management_mode]);

        // Additional Headers
        $additional_headers = [];

        // CEK
        $this->log(LogLevel::DEBUG, 'Trying to determine the content encryption key (CEK)');
        $cek = $this->determineCEK(
            $jwe,
            $content_encryption_algorithm,
            $key_management_mode,
            $additional_headers
        );
        $this->log(LogLevel::DEBUG, 'The content encryption key has been determined', ['cek', $cek]);

        $nb_recipients = $jwe->countRecipients();

        $this->log(LogLevel::DEBUG, 'Trying to encrypt the content encryption key (CEK) for all recipients');
        for ($i = 0; $i < $nb_recipients; $i++) {
            $this->log(LogLevel::DEBUG, 'Processing with recipient #{index}', ['index', $i]);
            $this->processRecipient(
                $jwe,
                $jwe->getRecipient($i),
                $cek,
                $content_encryption_algorithm,
                $additional_headers
            );
            $this->log(LogLevel::DEBUG, 'Processing done');
        }

        if (!empty($additional_headers) && 1 === $jwe->countRecipients()) {
            $this->log(LogLevel::DEBUG, 'Additional headers will be added to the shared protected headers', ['additional_headers' => $additional_headers]);
            $jwe = $jwe->withSharedProtectedHeaders(array_merge(
                $jwe->getSharedProtectedHeaders(),
                $additional_headers
            ));
            $this->log(LogLevel::DEBUG, 'Additional headers added');
        }

        // IV
        $this->log(LogLevel::DEBUG, 'Creating Initialization Vector (IV)');
        $iv_size = $content_encryption_algorithm->getIVSize();
        $iv = $this->createIV($iv_size);
        $this->log(LogLevel::DEBUG, 'Initialization Vector (IV) creation done', ['iv' => $iv]);

        $this->log(LogLevel::DEBUG, 'Trying to encrypt the JWE object ');
        $this->encryptJWE($jwe, $content_encryption_algorithm, $cek, $iv, $compression_method);
        $this->log(LogLevel::DEBUG, 'JWE object encryption done.');
    }

    /**
     * @param \Jose\Object\JWEInterface                           $jwe
     * @param \Jose\Object\RecipientInterface                     $recipient
     * @param string                                              $cek
     * @param \Jose\Algorithm\ContentEncryptionAlgorithmInterface $content_encryption_algorithm
     * @param array                                               $additional_headers
     */
    private function processRecipient(JWEInterface $jwe,
                                      RecipientInterface &$recipient,
                                      $cek,
                                      ContentEncryptionAlgorithmInterface $content_encryption_algorithm,
                                      array &$additional_headers
    ) {
        if (null === $recipient->getRecipientKey()) {
            $this->log(LogLevel::WARNING, 'The recipient key is not set. Aborting.');
            return;
        }
        $complete_headers = array_merge(
            $jwe->getSharedProtectedHeaders(),
            $jwe->getSharedHeaders(),
            $recipient->getHeaders()
        );

        $this->log(LogLevel::DEBUG, 'Trying to find the key encryption algorithm');
        $key_encryption_algorithm = $this->findKeyEncryptionAlgorithm($complete_headers);
        $this->log(LogLevel::DEBUG, 'The key encryption algorithm has been found', ['key_encryption_algorithm' => $key_encryption_algorithm]);

        // We check keys (usage and algorithm if restrictions are set)
        $this->log(LogLevel::DEBUG, 'Checking recipient key usage');
        $this->checkKeys(
            $key_encryption_algorithm,
            $content_encryption_algorithm,
            $recipient->getRecipientKey()
        );
        $this->log(LogLevel::DEBUG, 'Recipient key usage checks done');

        $this->log(LogLevel::DEBUG, 'Trying to compute the content encryption key');
        $encrypted_content_encryption_key = $this->getEncryptedKey(
            $complete_headers,
            $cek,
            $key_encryption_algorithm,
            $content_encryption_algorithm,
            $additional_headers,
            $recipient->getRecipientKey()
        );
        $this->log(LogLevel::DEBUG, 'Content encryption key computation done', ['encrypted_content_encryption_key' => $encrypted_content_encryption_key]);

        $recipient_headers = $recipient->getHeaders();
        if (!empty($additional_headers) && 1 !== $jwe->countRecipients()) {
            $recipient_headers = array_merge(
                $recipient_headers,
                $additional_headers
            );
            $additional_headers = [];
        }

        $recipient = Recipient::createRecipientFromLoadedJWE($recipient_headers, $encrypted_content_encryption_key);
    }

    /**
     * @param \Jose\Object\JWEInterface                           $jwe
     * @param \Jose\Algorithm\ContentEncryptionAlgorithmInterface $content_encryption_algorithm
     * @param string                                              $key_management_mode
     * @param array                                               $additional_headers
     *
     * @return string
     */
    private function determineCEK(JWEInterface $jwe,
                                  ContentEncryptionAlgorithmInterface $content_encryption_algorithm,
                                  $key_management_mode,
                                  array &$additional_headers
    ) {
        switch ($key_management_mode) {
            case KeyEncryptionInterface::MODE_ENCRYPT:
            case KeyEncryptionInterface::MODE_WRAP:
                return $this->createCEK($content_encryption_algorithm->getCEKSize());
            case KeyEncryptionInterface::MODE_AGREEMENT:
                Assertion::eq(1, $jwe->countRecipients(), 'Unable to encrypt for multiple recipients using key agreement algorithms.');

                $complete_headers = array_merge(
                    $jwe->getSharedProtectedHeaders(),
                    $jwe->getSharedHeaders(),
                    $jwe->getRecipient(0)->getHeaders()
                );
                $algorithm = $this->findKeyEncryptionAlgorithm($complete_headers);

                return $algorithm->getAgreementKey($content_encryption_algorithm->getCEKSize(), $content_encryption_algorithm->getAlgorithmName(), $jwe->getRecipient(0)->getRecipientKey(), $complete_headers, $additional_headers);
            case KeyEncryptionInterface::MODE_DIRECT:
                Assertion::eq(1, $jwe->countRecipients(), 'Unable to encrypt for multiple recipients using key agreement algorithms.');

                Assertion::eq($jwe->getRecipient(0)->getRecipientKey()->get('kty'), 'oct', 'Wrong key type.');
                Assertion::true($jwe->getRecipient(0)->getRecipientKey()->has('k'), 'The key parameter "k" is missing.');

                return Base64Url::decode($jwe->getRecipient(0)->getRecipientKey()->get('k'));
            default:
                throw new \InvalidArgumentException(sprintf('Unsupported key management mode "%s".', $key_management_mode));
        }
    }

    /**
     * @param \Jose\Object\JWEInterface $jwe
     *
     * @return string
     */
    private function getKeyManagementMode(JWEInterface $jwe)
    {
        $mode = null;
        $recipients = $jwe->getRecipients();
        
        foreach ($recipients as $recipient) {
            $complete_headers = array_merge(
                $jwe->getSharedProtectedHeaders(),
                $jwe->getSharedHeaders(),
                $recipient->getHeaders()
            );
            Assertion::keyExists($complete_headers, 'alg', 'Parameter "alg" is missing.');

            $key_encryption_algorithm = $this->getJWAManager()->getAlgorithm($complete_headers['alg']);
            Assertion::isInstanceOf($key_encryption_algorithm, KeyEncryptionAlgorithmInterface::class, sprintf('The key encryption algorithm "%s" is not supported or not a key encryption algorithm instance.', $complete_headers['alg']));

            if (null === $mode) {
                $mode = $key_encryption_algorithm->getKeyManagementMode();
            } else {
                Assertion::true(
                    $this->areKeyManagementModesCompatible($mode, $key_encryption_algorithm->getKeyManagementMode()),
                    'Foreign key management mode forbidden.'
                );
            }
        }

        return $mode;
    }

    /**
     * @param \Jose\Object\JWEInterface $jwe
     *
     * @return \Jose\Compression\CompressionInterface|null
     */
    private function getCompressionMethod(JWEInterface $jwe)
    {
        $method = null;
        $nb_recipients = $jwe->countRecipients();

        for ($i = 0; $i < $nb_recipients; $i++) {
            $complete_headers = array_merge(
                $jwe->getSharedProtectedHeaders(),
                $jwe->getSharedHeaders(),
                $jwe->getRecipient($i)->getHeaders()
            );
            if (array_key_exists('zip', $complete_headers)) {
                if (null === $method) {
                    if (0 === $i) {
                        $method = $complete_headers['zip'];
                    } else {
                        throw new \InvalidArgumentException('Inconsistent "zip" parameter.');
                    }
                } else {
                    Assertion::eq($method, $complete_headers['zip'], 'Inconsistent "zip" parameter.');
                }
            } else {
                Assertion::eq(null, $method, 'Inconsistent "zip" parameter.');
            }
        }

        if (null === $method) {
            return;
        }

        $compression_method = $this->getCompressionManager()->getCompressionAlgorithm($method);
        Assertion::isInstanceOf($compression_method, CompressionInterface::class, sprintf('Compression method "%s" not supported.', $method));

        return $compression_method;
    }

    /**
     * @param \Jose\Object\JWEInterface $jwe
     *
     * @return \Jose\Algorithm\ContentEncryptionAlgorithmInterface
     */
    private function getContentEncryptionAlgorithm(JWEInterface $jwe)
    {
        $algorithm = null;

        foreach ($jwe->getRecipients() as $recipient) {
            $complete_headers = array_merge(
                $jwe->getSharedProtectedHeaders(),
                $jwe->getSharedHeaders(),
                $recipient->getHeaders()
            );
            Assertion::keyExists($complete_headers, 'enc', 'Parameter "enc" is missing.');
            if (null === $algorithm) {
                $algorithm = $complete_headers['enc'];
            } else {
                Assertion::eq($algorithm, $complete_headers['enc'], 'Foreign content encryption algorithms are not allowed.');
            }
        }

        $content_encryption_algorithm = $this->getJWAManager()->getAlgorithm($algorithm);
        Assertion::isInstanceOf($content_encryption_algorithm, ContentEncryptionAlgorithmInterface::class, sprintf('The content encryption algorithm "%s" is not supported or not a content encryption algorithm instance.', $algorithm));

        return $content_encryption_algorithm;
    }

    /**
     * @param \Jose\Object\JWEInterface                           $jwe
     * @param \Jose\Algorithm\ContentEncryptionAlgorithmInterface $content_encryption_algorithm
     * @param string                                              $cek
     * @param string                                              $iv
     * @param \Jose\Compression\CompressionInterface|null         $compression_method
     */
    private function encryptJWE(JWEInterface &$jwe,
                                ContentEncryptionAlgorithmInterface $content_encryption_algorithm,
                                $cek,
                                $iv,
                                CompressionInterface $compression_method = null
    ) {
        if (!empty($jwe->getSharedProtectedHeaders())) {
            $jwe = $jwe->withEncodedSharedProtectedHeaders(Base64Url::encode(json_encode($jwe->getSharedProtectedHeaders())));
        }

        // We encrypt the payload and get the tag
        $tag = null;
        $payload = $this->preparePayload($jwe->getPayload(), $compression_method);

        $ciphertext = $content_encryption_algorithm->encryptContent(
            $payload,
            $cek,
            $iv,
            $jwe->getAAD(),
            $jwe->getEncodedSharedProtectedHeaders(),
            $tag
        );

        $jwe = $jwe->withCiphertext($ciphertext);
        $jwe = $jwe->withIV($iv);

        // Tag
        if (null !== $tag) {
            $jwe = $jwe->withTag($tag);
        }
    }

    /**
     * @param \Jose\Algorithm\KeyEncryptionAlgorithmInterface     $key_encryption_algorithm
     * @param \Jose\Algorithm\ContentEncryptionAlgorithmInterface $content_encryption_algorithm
     * @param \Jose\Object\JWKInterface                           $recipient_key
     */
    private function checkKeys(KeyEncryptionAlgorithmInterface $key_encryption_algorithm, ContentEncryptionAlgorithmInterface $content_encryption_algorithm, JWKInterface $recipient_key)
    {
        $this->checkKeyUsage($recipient_key, 'encryption');
        if ('dir' !== $key_encryption_algorithm->getAlgorithmName()) {
            $this->checkKeyAlgorithm($recipient_key, $key_encryption_algorithm->getAlgorithmName());
        } else {
            $this->checkKeyAlgorithm($recipient_key, $content_encryption_algorithm->getAlgorithmName());
        }
    }

    /**
     * @param string $current
     * @param string $new
     *
     * @return bool
     */
    private function areKeyManagementModesCompatible($current, $new)
    {
        $agree = KeyEncryptionAlgorithmInterface::MODE_AGREEMENT;
        $dir = KeyEncryptionAlgorithmInterface::MODE_DIRECT;
        $enc = KeyEncryptionAlgorithmInterface::MODE_ENCRYPT;
        $wrap = KeyEncryptionAlgorithmInterface::MODE_WRAP;

        $supported_key_management_mode_combinations = [
            $enc.$enc     => true,
            $enc.$wrap    => true,
            $wrap.$enc    => true,
            $wrap.$wrap   => true,
            $agree.$agree => false,
            $agree.$dir   => false,
            $agree.$enc   => false,
            $agree.$wrap  => false,
            $dir.$agree   => false,
            $dir.$dir     => false,
            $dir.$enc     => false,
            $dir.$wrap    => false,
            $enc.$agree   => false,
            $enc.$dir     => false,
            $wrap.$agree  => false,
            $wrap.$dir    => false,
        ];

        if (array_key_exists($current.$new, $supported_key_management_mode_combinations)) {
            return $supported_key_management_mode_combinations[$current.$new];
        }

        return false;
    }

    /**
     * @param string                                      $payload
     * @param \Jose\Compression\CompressionInterface|null $compression_method
     *
     * @return string
     */
    private function preparePayload($payload, CompressionInterface $compression_method = null)
    {
        $prepared = is_string($payload) ? $payload : json_encode($payload);

        Assertion::notNull($prepared, 'The payload is empty or cannot encoded into JSON.');

        if (null === $compression_method) {
            return $prepared;
        }
        $compressed_payload = $compression_method->compress($prepared);
        Assertion::string($compressed_payload, 'Compression failed.');

        return $compressed_payload;
    }

    /**
     * @param array                                               $complete_headers
     * @param string                                              $cek
     * @param \Jose\Algorithm\KeyEncryptionAlgorithmInterface     $key_encryption_algorithm
     * @param \Jose\Algorithm\ContentEncryptionAlgorithmInterface $content_encryption_algorithm
     * @param \Jose\Object\JWKInterface                           $recipient_key
     * @param array                                               $additional_headers
     *
     * @return string|null
     */
    private function getEncryptedKey(array $complete_headers, $cek, KeyEncryptionAlgorithmInterface $key_encryption_algorithm, ContentEncryptionAlgorithmInterface $content_encryption_algorithm, array &$additional_headers, JWKInterface $recipient_key)
    {
        if ($key_encryption_algorithm instanceof KeyEncryptionInterface) {
            return $this->getEncryptedKeyFromKeyEncryptionAlgorithm($complete_headers, $cek, $key_encryption_algorithm, $recipient_key, $additional_headers);
        } elseif ($key_encryption_algorithm instanceof KeyWrappingInterface) {
            return $this->getEncryptedKeyFromKeyWrappingAlgorithm($complete_headers, $cek, $key_encryption_algorithm, $recipient_key, $additional_headers);
        } elseif ($key_encryption_algorithm instanceof KeyAgreementWrappingInterface) {
            return $this->getEncryptedKeyFromKeyAgreementAndKeyWrappingAlgorithm($complete_headers, $cek, $key_encryption_algorithm, $content_encryption_algorithm, $additional_headers, $recipient_key);
        }

        // Using KeyAgreementInterface or DirectEncryptionInterface, the encrypted key is an empty string
    }

    /**
     * @param array                                                       $complete_headers
     * @param string                                                      $cek
     * @param \Jose\Algorithm\KeyEncryption\KeyAgreementWrappingInterface $key_encryption_algorithm
     * @param \Jose\Algorithm\ContentEncryptionAlgorithmInterface         $content_encryption_algorithm
     * @param array                                                       $additional_headers
     * @param \Jose\Object\JWKInterface                                   $recipient_key
     *
     * @return string
     */
    private function getEncryptedKeyFromKeyAgreementAndKeyWrappingAlgorithm(array $complete_headers, $cek, KeyAgreementWrappingInterface $key_encryption_algorithm, ContentEncryptionAlgorithmInterface $content_encryption_algorithm, array &$additional_headers, JWKInterface $recipient_key)
    {
        $jwt_cek = $key_encryption_algorithm->wrapAgreementKey($recipient_key, $cek, $content_encryption_algorithm->getCEKSize(), $complete_headers, $additional_headers);

        return $jwt_cek;
    }

    /**
     * @param array                                                $complete_headers
     * @param string                                               $cek
     * @param \Jose\Algorithm\KeyEncryption\KeyEncryptionInterface $key_encryption_algorithm
     * @param \Jose\Object\JWKInterface                            $recipient_key
     * @param array                                                $additional_headers
     *
     * @return string
     */
    private function getEncryptedKeyFromKeyEncryptionAlgorithm(array $complete_headers, $cek, KeyEncryptionInterface $key_encryption_algorithm, JWKInterface $recipient_key, array &$additional_headers)
    {
        return $key_encryption_algorithm->encryptKey(
            $recipient_key,
            $cek,
            $complete_headers,
            $additional_headers
        );
    }

    /**
     * @param array                                              $complete_headers
     * @param string                                             $cek
     * @param \Jose\Algorithm\KeyEncryption\KeyWrappingInterface $key_encryption_algorithm
     * @param \Jose\Object\JWKInterface                          $recipient_key
     * @param array                                              $additional_headers
     *
     * @return string
     */
    private function getEncryptedKeyFromKeyWrappingAlgorithm(array $complete_headers, $cek, KeyWrappingInterface $key_encryption_algorithm, JWKInterface $recipient_key, &$additional_headers)
    {
        return $key_encryption_algorithm->wrapKey(
            $recipient_key,
            $cek,
            $complete_headers,
            $additional_headers
        );
    }

    /**
     * @param array $complete_headers
     *
     * @return \Jose\Algorithm\KeyEncryptionAlgorithmInterface
     */
    private function findKeyEncryptionAlgorithm(array $complete_headers)
    {
        Assertion::keyExists($complete_headers, 'alg', 'Parameter "alg" is missing.');

        $key_encryption_algorithm = $this->getJWAManager()->getAlgorithm($complete_headers['alg']);
        Assertion::isInstanceOf($key_encryption_algorithm, KeyEncryptionAlgorithmInterface::class, sprintf('The key encryption algorithm "%s" is not supported or not a key encryption algorithm instance.', $complete_headers['alg']));

        return $key_encryption_algorithm;
    }

    /**
     * @param int $size
     *
     * @return string
     */
    private function createCEK($size)
    {
        return random_bytes($size / 8);
    }

    /**
     * @param int $size
     *
     * @return string
     */
    private function createIV($size)
    {
        return random_bytes($size / 8);
    }
}