CryptLib/Cipher/Block/AbstractMode.php

   1 <?php
   2 /**
   3  * An abstract class for simplifing creation of cipher modes
   4  *
   5  * PHP version 5.3
   6  *
   7  * @category   PHPCryptLib
   8  * @package    Cipher
   9  * @subpackage Block
  10  * @author     Anthony Ferrara <ircmaxell@ircmaxell.com>
  11  * @copyright  2011 The Authors
  12  * @license    http://www.opensource.org/licenses/mit-license.html  MIT License
  13  * @version    Build @@version@@
  14  */
  15
  16 namespace CryptLib\Cipher\Block;
  17
  18 /**
  19  * An abstract class for simplifing creation of cipher modes
  20  *
  21  * @category   PHPCryptLib
  22  * @package    Cipher
  23  * @subpackage Block
  24  */
  25 abstract class AbstractMode implements \CryptLib\Cipher\Block\Mode {
  26
  27     /**
  28      * @var string Additional data to authenticate with
  29      */
  30     protected $adata = '';
  31
  32     /**
  33      * @var Cipher The cipher to use for this mode instance
  34      */
  35     protected $cipher = null;
  36
  37     /**
  38      * @var string The initialization Vector to use for this mode
  39      */
  40     protected $initv = '';
  41
  42     /**
  43      * @var string The mode name for the current instance
  44      */
  45     protected $mode = '';
  46
  47     /**
  48      * @var array Mode specific options
  49      */
  50     protected $options = array();
  51
  52     /**
  53      * @var string The internal state of the mode
  54      */
  55     protected $state = '';
  56
  57     /**
  58      * Perform the decryption of the current block
  59      *
  60      * @param string $data The data to decrypt
  61      *
  62      * @return string The decrypted data
  63      */
  64     abstract protected function decryptBlock($data);
  65
  66     /**
  67      * Perform the encryption of the current block
  68      *
  69      * @param string $data The data to encrypt
  70      *
  71      * @return string The encrypted data
  72      */
  73     abstract protected function encryptBlock($data);
  74
  75     /**
  76      * Build the instance of the cipher mode
  77      *
  78      * @param Cipher $cipher  The cipher to use for encryption/decryption
  79      * @param string $initv   The initialization vector (empty if not needed)
  80      * @param array  $options An array of mode-specific options
  81      */
  82     public function __construct(
  83         \CryptLib\Cipher\Block\Cipher $cipher,
  84         $initv,
  85         array $options = array()
  86     ) {
  87         $class         = strtolower(get_class($this));
  88         $class         = substr($class, strrpos($class, '\\') + 1);
  89         $this->mode    = $class;
  90         $this->options = $options + $this->options;
  91         $this->cipher  = $cipher;
  92         $this->initv   = $initv;
  93         $this->reset();
  94     }
  95
  96     /**
  97      * Decrypt the data using the supplied key, cipher and initialization vector
  98      *
  99      * @param string $data The data to decrypt
 100      *
 101      * @return string The decrypted data
 102      */
 103     public function decrypt($data) {
 104         $this->enforceBlockSize($data);
 105         return $this->decryptBlock($data);
 106     }
 107
 108     /**
 109      * Encrypt the data using the supplied key, cipher and initialization vector
 110      *
 111      * @param string $data The data to encrypt
 112      *
 113      * @return string The encrypted data
 114      */
 115     public function encrypt($data) {
 116         $this->enforceBlockSize($data);
 117         return $this->encryptBlock($data);
 118     }
 119
 120     /**
 121      * Finish the mode and append any additional data necessary
 122      *
 123      * @return string Any additional data
 124      */
 125     public function finish() {
 126         return '';
 127     }
 128
 129     /**
 130      * Get the name of the current mode implementation
 131      *
 132      * @return string The current mode name
 133      */
 134     public function getMode() {
 135         return $this->mode;
 136     }
 137
 138     /**
 139      * Reset the mode to start over (destroying any intermediate state)
 140      *
 141      * @return void
 142      */
 143     public function reset() {
 144         $this->state = $this->initv;
 145     }
 146
 147     /**
 148      * Enforce the data block is the correct size for the cipher
 149      *
 150      * @param string $data The data to check
 151      *
 152      * @return void
 153      * @throws InvalidArgumentException if the block size is not correct
 154      */
 155     protected function enforceBlockSize($data) {
 156         if (strlen($data) != $this->cipher->getBlockSize()) {
 157             throw new \InvalidArgumentException(
 158                 sprintf(
 159                     'The data block must match the block size [%d:%d]',
 160                     strlen($data),
 161                     $this->cipher->getBlockSize()
 162                 )
 163             );
 164         }
 165     }
 166 }