109 lines
3.5 KiB
PHP
109 lines
3.5 KiB
PHP
<?php
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namespace UglyRobot\Infinite_Uploads\Aws\Crypto;
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use UglyRobot\Infinite_Uploads\GuzzleHttp\Psr7\StreamDecoratorTrait;
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use LogicException;
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use UglyRobot\Infinite_Uploads\Psr\Http\Message\StreamInterface;
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use UglyRobot\Infinite_Uploads\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 \UglyRobot\Infinite_Uploads\Aws\Crypto\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(\UglyRobot\Infinite_Uploads\Psr\Http\Message\StreamInterface $cipherText, $key, \UglyRobot\Infinite_Uploads\Aws\Crypto\Cipher\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 $this->cipherMethod->getCurrentIv();
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}
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public function getSize()
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{
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$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 $plainTextSize;
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}
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public function isWritable()
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{
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return false;
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}
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public function read($length)
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{
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if ($length > strlen($this->buffer)) {
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$this->buffer .= $this->decryptBlock(self::BLOCK_SIZE * ceil(($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, $whence = SEEK_SET)
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{
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if ($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 .= $this->stream->read($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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