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<?php |
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namespace Dudlewebs\WPMCS\s3\Aws\Crypto; |
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use Dudlewebs\WPMCS\s3\GuzzleHttp\Psr7\StreamDecoratorTrait; |
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use LogicException; |
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use Dudlewebs\WPMCS\s3\Psr\Http\Message\StreamInterface; |
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use Dudlewebs\WPMCS\s3\Aws\Crypto\Cipher\CipherMethod; |
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/** |
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* @internal Represents a stream of data to be decrypted with passed cipher. |
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*/ |
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class AesDecryptingStream implements AesStreamInterface |
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{ |
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const BLOCK_SIZE = 16; |
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// 128 bits |
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use StreamDecoratorTrait; |
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/** |
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* @var string |
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*/ |
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private $buffer = ''; |
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/** |
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* @var CipherMethod |
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*/ |
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private $cipherMethod; |
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/** |
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* @var string |
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*/ |
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private $key; |
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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 CipherMethod $cipherMethod |
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*/ |
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public function __construct(StreamInterface $cipherText, $key, CipherMethod $cipherMethod) |
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{ |
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$this->stream = $cipherText; |
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$this->key = $key; |
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$this->cipherMethod = clone $cipherMethod; |
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} |
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public function getOpenSslName() |
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{ |
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return $this->cipherMethod->getOpenSslName(); |
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} |
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public function getAesName() |
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{ |
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return $this->cipherMethod->getAesName(); |
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} |
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public function getCurrentIv() |
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{ |
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return $this->cipherMethod->getCurrentIv(); |
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} |
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public function getSize() : ?int |
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{ |
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$plainTextSize = $this->stream->getSize(); |
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if ($this->cipherMethod->requiresPadding()) { |
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// PKCS7 padding requires that between 1 and self::BLOCK_SIZE be |
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// added to the plaintext to make it an even number of blocks. The |
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// plaintext is between strlen($cipherText) - self::BLOCK_SIZE and |
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// strlen($cipherText) - 1 |
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return null; |
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} |
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return $plainTextSize; |
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} |
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public function isWritable() : bool |
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{ |
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return \false; |
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} |
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public function read($length) : string |
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{ |
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if ($length > \strlen($this->buffer)) { |
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$this->buffer .= $this->decryptBlock((int) (self::BLOCK_SIZE * \ceil(($length - \strlen($this->buffer)) / self::BLOCK_SIZE))); |
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} |
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$data = \substr($this->buffer, 0, $length); |
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$this->buffer = \substr($this->buffer, $length); |
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return $data ? $data : ''; |
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} |
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public function seek($offset, $whence = \SEEK_SET) : void |
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{ |
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if ($offset === 0 && $whence === \SEEK_SET) { |
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$this->buffer = ''; |
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$this->cipherMethod->seek(0, \SEEK_SET); |
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$this->stream->seek(0, \SEEK_SET); |
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} else { |
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throw new LogicException('AES encryption streams only support being' . ' rewound, not arbitrary seeking.'); |
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} |
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} |
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private function decryptBlock($length) |
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{ |
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if ($this->stream->eof()) { |
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return ''; |
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} |
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$cipherText = ''; |
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do { |
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$cipherText .= $this->stream->read((int) ($length - \strlen($cipherText))); |
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} while (\strlen($cipherText) < $length && !$this->stream->eof()); |
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$options = \OPENSSL_RAW_DATA; |
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if (!$this->stream->eof() && $this->stream->getSize() !== $this->stream->tell()) { |
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$options |= \OPENSSL_ZERO_PADDING; |
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} |
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$plaintext = \openssl_decrypt($cipherText, $this->cipherMethod->getOpenSslName(), $this->key, $options, $this->cipherMethod->getCurrentIv()); |
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$this->cipherMethod->update($cipherText); |
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return $plaintext; |
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} |
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} |
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