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