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<?php
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namespace Aws\Crypto\Cipher;
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use \InvalidArgumentException;
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use \LogicException;
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/**
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 * An implementation of the CBC cipher for use with an AesEncryptingStream or
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 * AesDecrypting stream.
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 *
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 * This cipher method is deprecated and in maintenance mode - no new updates will be
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 * released. Please see https://docs.aws.amazon.com/general/latest/gr/aws_sdk_cryptography.html
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 * for more information.
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 *
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 * @deprecated
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 */
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class Cbc implements CipherMethod
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{
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    const BLOCK_SIZE = 16;
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    /**
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     * @var string
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     */
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    private $baseIv;
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    /**
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     * @var string
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     */
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    private $iv;
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    /**
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     * @var int
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     */
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    private $keySize;
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    /**
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     * @param string $iv Base Initialization Vector for the cipher.
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     * @param int $keySize Size of the encryption key, in bits, that will be
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     *                     used.
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     *
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     * @throws InvalidArgumentException Thrown if the passed iv does not match
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     *                                  the iv length required by the cipher.
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     */
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    public function __construct($iv, $keySize = 256)
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    {
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        $this->baseIv = $this->iv = $iv;
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        $this->keySize = $keySize;
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        if (strlen($iv) !== openssl_cipher_iv_length($this->getOpenSslName())) {
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            throw new InvalidArgumentException('Invalid initialization vector');
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        }
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    }
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    public function getOpenSslName()
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    {
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        return "aes-{$this->keySize}-cbc";
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    }
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    public function getAesName()
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    {
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        return 'AES/CBC/PKCS5Padding';
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    }
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    public function getCurrentIv()
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    {
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        return $this->iv;
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    }
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    public function requiresPadding()
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    {
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        return true;
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    }
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    public function seek($offset, $whence = SEEK_SET)
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    {
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        if ($offset === 0 && $whence === SEEK_SET) {
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            $this->iv = $this->baseIv;
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        } else {
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            throw new LogicException('CBC initialization only support being'
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                . ' rewound, not arbitrary seeking.');
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        }
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    }
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    public function update($cipherTextBlock)
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    {
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        $this->iv = substr($cipherTextBlock, self::BLOCK_SIZE * -1);
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    }
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}