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<?php
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namespace Aws\Crypto;
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use Aws\Exception\CryptoException;
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use GuzzleHttp\Psr7;
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use GuzzleHttp\Psr7\StreamDecoratorTrait;
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use Psr\Http\Message\StreamInterface;
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use Aws\Crypto\Polyfill\AesGcm;
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use Aws\Crypto\Polyfill\Key;
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/**
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 * @internal Represents a stream of data to be gcm decrypted.
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 */
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class AesGcmDecryptingStream implements AesStreamInterface
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{
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    use StreamDecoratorTrait;
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    private $aad;
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    private $initializationVector;
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    private $key;
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    private $keySize;
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    private $cipherText;
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    private $tag;
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    private $tagLength;
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    /**
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     * @var StreamInterface
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     */
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    private $stream;
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    /**
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     * @param StreamInterface $cipherText
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     * @param string $key
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     * @param string $initializationVector
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     * @param string $tag
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     * @param string $aad
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     * @param int $tagLength
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     * @param int $keySize
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     */
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    public function __construct(
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        StreamInterface $cipherText,
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        $key,
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        $initializationVector,
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        $tag,
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        $aad = '',
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        $tagLength = 128,
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        $keySize = 256
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    ) {
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        $this->cipherText = $cipherText;
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        $this->key = $key;
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        $this->initializationVector = $initializationVector;
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        $this->tag = $tag;
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        $this->aad = $aad;
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        $this->tagLength = $tagLength;
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        $this->keySize = $keySize;
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        // unsetting the property forces the first access to go through
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        // __get().
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        unset($this->stream);
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    }
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    public function getOpenSslName()
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    {
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        return "aes-{$this->keySize}-gcm";
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    }
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    public function getAesName()
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    {
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        return 'AES/GCM/NoPadding';
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    }
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    public function getCurrentIv()
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    {
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        return $this->initializationVector;
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    }
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    public function createStream()
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    {
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        if (version_compare(PHP_VERSION, '7.1', '<')) {
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            return Psr7\Utils::streamFor(AesGcm::decrypt(
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                (string) $this->cipherText,
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                $this->initializationVector,
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                new Key($this->key),
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                $this->aad,
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                $this->tag,
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                $this->keySize
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            ));
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        } else {
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            $result = \openssl_decrypt(
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                (string)$this->cipherText,
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                $this->getOpenSslName(),
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                $this->key,
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                OPENSSL_RAW_DATA,
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                $this->initializationVector,
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                $this->tag,
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                $this->aad
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            );
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            if ($result === false) {
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                throw new CryptoException('The requested object could not be'
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                    . ' decrypted due to an invalid authentication tag.');
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            }
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            return Psr7\Utils::streamFor($result);
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        }
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    }
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    public function isWritable(): bool
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    {
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        return false;
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    }
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}