268 lines
11 KiB
PHP
268 lines
11 KiB
PHP
<?php
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declare(strict_types=1);
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/*
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* The MIT License (MIT)
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*
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* Copyright (c) 2014-2020 Spomky-Labs
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*
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* This software may be modified and distributed under the terms
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* of the MIT license. See the LICENSE file for details.
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*/
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namespace Jose\Component\Encryption;
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use function array_key_exists;
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use InvalidArgumentException;
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use function is_string;
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use Jose\Component\Core\Algorithm;
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use Jose\Component\Core\AlgorithmManager;
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use Jose\Component\Core\JWK;
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use Jose\Component\Core\JWKSet;
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use Jose\Component\Core\Util\KeyChecker;
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use Jose\Component\Encryption\Algorithm\ContentEncryptionAlgorithm;
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use Jose\Component\Encryption\Algorithm\KeyEncryption\DirectEncryption;
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use Jose\Component\Encryption\Algorithm\KeyEncryption\KeyAgreement;
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use Jose\Component\Encryption\Algorithm\KeyEncryption\KeyAgreementWithKeyWrapping;
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use Jose\Component\Encryption\Algorithm\KeyEncryption\KeyEncryption;
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use Jose\Component\Encryption\Algorithm\KeyEncryption\KeyWrapping;
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use Jose\Component\Encryption\Algorithm\KeyEncryptionAlgorithm;
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use Jose\Component\Encryption\Compression\CompressionMethodManager;
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use Throwable;
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class JWEDecrypter
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{
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/**
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* @var AlgorithmManager
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*/
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private $keyEncryptionAlgorithmManager;
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/**
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* @var AlgorithmManager
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*/
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private $contentEncryptionAlgorithmManager;
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/**
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* @var CompressionMethodManager
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*/
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private $compressionMethodManager;
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public function __construct(AlgorithmManager $keyEncryptionAlgorithmManager, AlgorithmManager $contentEncryptionAlgorithmManager, CompressionMethodManager $compressionMethodManager)
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{
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$this->keyEncryptionAlgorithmManager = $keyEncryptionAlgorithmManager;
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$this->contentEncryptionAlgorithmManager = $contentEncryptionAlgorithmManager;
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$this->compressionMethodManager = $compressionMethodManager;
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}
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/**
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* Returns the key encryption algorithm manager.
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*/
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public function getKeyEncryptionAlgorithmManager(): AlgorithmManager
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{
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return $this->keyEncryptionAlgorithmManager;
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}
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/**
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* Returns the content encryption algorithm manager.
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*/
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public function getContentEncryptionAlgorithmManager(): AlgorithmManager
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{
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return $this->contentEncryptionAlgorithmManager;
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}
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/**
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* Returns the compression method manager.
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*/
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public function getCompressionMethodManager(): CompressionMethodManager
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{
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return $this->compressionMethodManager;
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}
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/**
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* This method will try to decrypt the given JWE and recipient using a JWK.
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*
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* @param JWE $jwe A JWE object to decrypt
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* @param JWK $jwk The key used to decrypt the input
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* @param int $recipient The recipient used to decrypt the token
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*/
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public function decryptUsingKey(JWE &$jwe, JWK $jwk, int $recipient, ?JWK $senderKey = null): bool
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{
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$jwkset = new JWKSet([$jwk]);
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return $this->decryptUsingKeySet($jwe, $jwkset, $recipient, $senderKey);
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}
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/**
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* This method will try to decrypt the given JWE and recipient using a JWKSet.
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*
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* @param JWE $jwe A JWE object to decrypt
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* @param JWKSet $jwkset The key set used to decrypt the input
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* @param JWK $jwk The key used to decrypt the token in case of success
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* @param int $recipient The recipient used to decrypt the token in case of success
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*
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* @throws InvalidArgumentException if no key is set is the keyset
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* @throws InvalidArgumentException if the token has no recipients
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*/
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public function decryptUsingKeySet(JWE &$jwe, JWKSet $jwkset, int $recipient, JWK &$jwk = null, ?JWK $senderKey = null): bool
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{
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if (0 === $jwkset->count()) {
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throw new InvalidArgumentException('No key in the key set.');
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}
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if (null !== $jwe->getPayload()) {
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return true;
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}
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if (0 === $jwe->countRecipients()) {
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throw new InvalidArgumentException('The JWE does not contain any recipient.');
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}
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$plaintext = $this->decryptRecipientKey($jwe, $jwkset, $recipient, $jwk, $senderKey);
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if (null !== $plaintext) {
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$jwe = $jwe->withPayload($plaintext);
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return true;
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}
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return false;
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}
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private function decryptRecipientKey(JWE $jwe, JWKSet $jwkset, int $i, JWK &$successJwk = null, ?JWK $senderKey = null): ?string
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{
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$recipient = $jwe->getRecipient($i);
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$completeHeader = array_merge($jwe->getSharedProtectedHeader(), $jwe->getSharedHeader(), $recipient->getHeader());
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$this->checkCompleteHeader($completeHeader);
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$key_encryption_algorithm = $this->getKeyEncryptionAlgorithm($completeHeader);
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$content_encryption_algorithm = $this->getContentEncryptionAlgorithm($completeHeader);
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$this->checkIvSize($jwe->getIV(), $content_encryption_algorithm->getIVSize());
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foreach ($jwkset as $recipientKey) {
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try {
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KeyChecker::checkKeyUsage($recipientKey, 'decryption');
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if ('dir' !== $key_encryption_algorithm->name()) {
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KeyChecker::checkKeyAlgorithm($recipientKey, $key_encryption_algorithm->name());
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} else {
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KeyChecker::checkKeyAlgorithm($recipientKey, $content_encryption_algorithm->name());
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}
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$cek = $this->decryptCEK($key_encryption_algorithm, $content_encryption_algorithm, $recipientKey, $senderKey, $recipient, $completeHeader);
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$this->checkCekSize($cek, $key_encryption_algorithm, $content_encryption_algorithm);
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$payload = $this->decryptPayload($jwe, $cek, $content_encryption_algorithm, $completeHeader);
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$successJwk = $recipientKey;
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return $payload;
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} catch (Throwable $e) {
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//We do nothing, we continue with other keys
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continue;
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}
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}
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return null;
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}
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/**
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* @throws InvalidArgumentException if the Content Encryption Key size is invalid
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*/
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private function checkCekSize(string $cek, KeyEncryptionAlgorithm $keyEncryptionAlgorithm, ContentEncryptionAlgorithm $algorithm): void
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{
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if ($keyEncryptionAlgorithm instanceof DirectEncryption || $keyEncryptionAlgorithm instanceof KeyAgreement) {
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return;
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}
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if (mb_strlen($cek, '8bit') * 8 !== $algorithm->getCEKSize()) {
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throw new InvalidArgumentException('Invalid CEK size');
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}
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}
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/**
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* @throws InvalidArgumentException if the IV size is invalid
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*/
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private function checkIvSize(?string $iv, int $requiredIvSize): void
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{
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if (null === $iv && 0 !== $requiredIvSize) {
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throw new InvalidArgumentException('Invalid IV size');
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}
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if (is_string($iv) && mb_strlen($iv, '8bit') !== $requiredIvSize / 8) {
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throw new InvalidArgumentException('Invalid IV size');
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}
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}
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/**
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* @throws InvalidArgumentException if the CEK creation method is not supported
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*/
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private function decryptCEK(Algorithm $key_encryption_algorithm, ContentEncryptionAlgorithm $content_encryption_algorithm, JWK $recipientKey, ?JWK $senderKey, Recipient $recipient, array $completeHeader): string
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{
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if ($key_encryption_algorithm instanceof DirectEncryption) {
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return $key_encryption_algorithm->getCEK($recipientKey);
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}
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if ($key_encryption_algorithm instanceof KeyAgreement) {
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return $key_encryption_algorithm->getAgreementKey($content_encryption_algorithm->getCEKSize(), $content_encryption_algorithm->name(), $recipientKey, $senderKey, $completeHeader);
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}
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if ($key_encryption_algorithm instanceof KeyAgreementWithKeyWrapping) {
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return $key_encryption_algorithm->unwrapAgreementKey($recipientKey, $senderKey, $recipient->getEncryptedKey(), $content_encryption_algorithm->getCEKSize(), $completeHeader);
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}
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if ($key_encryption_algorithm instanceof KeyEncryption) {
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return $key_encryption_algorithm->decryptKey($recipientKey, $recipient->getEncryptedKey(), $completeHeader);
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}
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if ($key_encryption_algorithm instanceof KeyWrapping) {
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return $key_encryption_algorithm->unwrapKey($recipientKey, $recipient->getEncryptedKey(), $completeHeader);
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}
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throw new InvalidArgumentException('Unsupported CEK generation');
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}
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private function decryptPayload(JWE $jwe, string $cek, ContentEncryptionAlgorithm $content_encryption_algorithm, array $completeHeader): string
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{
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$payload = $content_encryption_algorithm->decryptContent($jwe->getCiphertext(), $cek, $jwe->getIV(), $jwe->getAAD(), $jwe->getEncodedSharedProtectedHeader(), $jwe->getTag());
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return $this->decompressIfNeeded($payload, $completeHeader);
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}
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private function decompressIfNeeded(string $payload, array $completeHeaders): string
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{
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if (array_key_exists('zip', $completeHeaders)) {
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$compression_method = $this->compressionMethodManager->get($completeHeaders['zip']);
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$payload = $compression_method->uncompress($payload);
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}
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return $payload;
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}
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/**
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* @throws InvalidArgumentException if a header parameter is missing
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*/
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private function checkCompleteHeader(array $completeHeaders): void
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{
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foreach (['enc', 'alg'] as $key) {
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if (!isset($completeHeaders[$key])) {
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throw new InvalidArgumentException(sprintf("Parameter '%s' is missing.", $key));
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}
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}
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}
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/**
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* @throws InvalidArgumentException if the key encryption algorithm is not supported or does not implement the KeyEncryptionAlgorithm interface
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*/
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private function getKeyEncryptionAlgorithm(array $completeHeaders): KeyEncryptionAlgorithm
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{
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$key_encryption_algorithm = $this->keyEncryptionAlgorithmManager->get($completeHeaders['alg']);
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if (!$key_encryption_algorithm instanceof KeyEncryptionAlgorithm) {
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throw new InvalidArgumentException(sprintf('The key encryption algorithm "%s" is not supported or does not implement KeyEncryptionAlgorithm interface.', $completeHeaders['alg']));
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}
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return $key_encryption_algorithm;
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}
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/**
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* @throws InvalidArgumentException if the content encryption algorithm is not supported or does not implement the ContentEncryption interface
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*/
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private function getContentEncryptionAlgorithm(array $completeHeader): ContentEncryptionAlgorithm
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{
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$content_encryption_algorithm = $this->contentEncryptionAlgorithmManager->get($completeHeader['enc']);
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if (!$content_encryption_algorithm instanceof ContentEncryptionAlgorithm) {
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throw new InvalidArgumentException(sprintf('The key encryption algorithm "%s" is not supported or does not implement the ContentEncryption interface.', $completeHeader['enc']));
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}
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return $content_encryption_algorithm;
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}
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}
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