109 lines
3.3 KiB
PHP
109 lines
3.3 KiB
PHP
<?php
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declare(strict_types=1);
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namespace Jose\Component\Encryption\Algorithm\KeyEncryption;
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use AESKW\Wrapper as WrapperInterface;
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use InvalidArgumentException;
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use Jose\Component\Core\JWK;
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use Jose\Component\Core\Util\Base64UrlSafe;
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use Override;
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use RuntimeException;
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use function extension_loaded;
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use function in_array;
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use function is_string;
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use function sprintf;
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use const OPENSSL_RAW_DATA;
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abstract readonly class AESGCMKW implements KeyWrapping
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{
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public function __construct()
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{
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if (! extension_loaded('openssl')) {
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throw new RuntimeException('Please install the OpenSSL extension');
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}
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if (! interface_exists(WrapperInterface::class)) {
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throw new RuntimeException('Please install "spomky-labs/aes-key-wrap" to use AES-KW algorithms');
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}
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}
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#[Override]
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public function allowedKeyTypes(): array
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{
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return ['oct'];
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}
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/**
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* @param array<string, mixed> $completeHeader
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* @param array<string, mixed> $additionalHeader
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*/
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#[Override]
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public function wrapKey(JWK $key, string $cek, array $completeHeader, array &$additionalHeader): string
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{
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$kek = $this->getKey($key);
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$iv = random_bytes(96 / 8);
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$additionalHeader['iv'] = Base64UrlSafe::encodeUnpadded($iv);
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$mode = sprintf('aes-%d-gcm', $this->getKeySize());
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$tag = '';
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$encrypted_cek = openssl_encrypt($cek, $mode, $kek, OPENSSL_RAW_DATA, $iv, $tag, '');
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if ($encrypted_cek === false) {
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throw new RuntimeException('Unable to encrypt the CEK');
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}
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$additionalHeader['tag'] = Base64UrlSafe::encodeUnpadded($tag);
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return $encrypted_cek;
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}
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/**
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* @param array<string, mixed> $completeHeader
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*/
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#[Override]
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public function unwrapKey(JWK $key, string $encrypted_cek, array $completeHeader): string
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{
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$kek = $this->getKey($key);
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(isset($completeHeader['iv']) && is_string($completeHeader['iv'])) || throw new InvalidArgumentException(
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'Parameter "iv" is missing.'
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);
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(isset($completeHeader['tag']) && is_string($completeHeader['tag'])) || throw new InvalidArgumentException(
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'Parameter "tag" is missing.'
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);
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$tag = Base64UrlSafe::decodeNoPadding($completeHeader['tag']);
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$iv = Base64UrlSafe::decodeNoPadding($completeHeader['iv']);
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$mode = sprintf('aes-%d-gcm', $this->getKeySize());
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$cek = openssl_decrypt($encrypted_cek, $mode, $kek, OPENSSL_RAW_DATA, $iv, $tag, '');
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if ($cek === false) {
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throw new RuntimeException('Unable to decrypt the CEK');
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}
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return $cek;
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}
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#[Override]
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public function getKeyManagementMode(): string
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{
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return self::MODE_WRAP;
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}
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protected function getKey(JWK $key): string
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{
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if (! in_array($key->get('kty'), $this->allowedKeyTypes(), true)) {
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throw new InvalidArgumentException('Wrong key type.');
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}
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if (! $key->has('k')) {
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throw new InvalidArgumentException('The key parameter "k" is missing.');
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}
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$k = $key->get('k');
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if (! is_string($k)) {
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throw new InvalidArgumentException('The key parameter "k" is invalid.');
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}
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return Base64UrlSafe::decodeNoPadding($k);
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}
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abstract protected function getKeySize(): int;
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}
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