php实现的rc4加密解密类定义与用法示例

本文实例讲述了php实现的rc4加密解密类。分享给大家供大家参考，具体如下：

class.rc4crypt.php文件：

<?php/*  * By julying.com */define('CRYPT_RC4_MODE_INTERNAL', 1);define('CRYPT_RC4_MODE_MCRYPT', 2);define('CRYPT_RC4_ENCRYPT', 0);define('CRYPT_RC4_DECRYPT', 1);class Crypt_RC4 { /**  * The Key  *  * @see Crypt_RC4::setKey()  * @var String  * @access private  */ var $key = "/0"; /**  * The Key Stream for encryption  *  * If CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT, this will be equal to the mcrypt object  *  * @see Crypt_RC4::setKey()  * @var Array  * @access private  */ var $encryptStream = false; /**  * The Key Stream for decryption  *  * If CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT, this will be equal to the mcrypt object  *  * @see Crypt_RC4::setKey()  * @var Array  * @access private  */ var $decryptStream = false; /**  * The $i and $j indexes for encryption  *  * @see Crypt_RC4::_crypt()  * @var Integer  * @access private  */ var $encryptIndex = 0; /**  * The $i and $j indexes for decryption  *  * @see Crypt_RC4::_crypt()  * @var Integer  * @access private  */ var $decryptIndex = 0; /**  * MCrypt parameters  *  * @see Crypt_RC4::setMCrypt()  * @var Array  * @access private  */ var $mcrypt = array('', ''); /**  * The Encryption Algorithm  *  * Only used if CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT. Only possible values are MCRYPT_RC4 or MCRYPT_ARCFOUR.  *  * @see Crypt_RC4::Crypt_RC4()  * @var Integer  * @access private  */ var $mode; /**  * Default Constructor.  *  * Determines whether or not the mcrypt extension should be used.  *  * @param optional Integer $mode  * @return Crypt_RC4  * @access public  */ var $continuousBuffer ; function Crypt_RC4() {  if ( !defined('CRYPT_RC4_MODE') ) {   switch (true) {    case extension_loaded('mcrypt') && (defined('MCRYPT_ARCFOUR') || defined('MCRYPT_RC4')):     // i'd check to see if rc4 was supported, by doing in_array('arcfour', mcrypt_list_algorithms('')),     // but since that can be changed after the object has been created, there doesn't seem to be     // a lot of point...     define('CRYPT_RC4_MODE', CRYPT_RC4_MODE_MCRYPT);     break;    default:     define('CRYPT_RC4_MODE', CRYPT_RC4_MODE_INTERNAL);   }  }  switch ( CRYPT_RC4_MODE ) {   case CRYPT_RC4_MODE_MCRYPT:    switch (true) {     case defined('MCRYPT_ARCFOUR'):      $this->mode = MCRYPT_ARCFOUR;      break;     case defined('MCRYPT_RC4');      $this->mode = MCRYPT_RC4;    }  } } /**  * Sets the key.  *  * Keys can be between 1 and 256 bytes long. If they are longer then 256 bytes, the first 256 bytes will  * be used. If no key is explicitly set, it'll be assumed to be a single null byte.  *  * @access public  * @param String $key  */ function setKey($key) {  $this->key = $key;  if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT ) {   return;  }  $keyLength = strlen($key);  $keyStream = array();  for ($i = 0; $i < 256; $i++) {   $keyStream[$i] = $i;  }  $j = 0;  for ($i = 0; $i < 256; $i++) {   $j = ($j + $keyStream[$i] + ord($key[$i % $keyLength])) & 255;   $temp = $keyStream[$i];   $keyStream[$i] = $keyStream[$j];   $keyStream[$j] = $temp;  }  $this->encryptIndex = $this->decryptIndex = array(0, 0);  $this->encryptStream = $this->decryptStream = $keyStream; } /**  * Dummy function.  *  * Some protocols, such as WEP, prepend an "initialization vector" to the key, effectively creating a new key [1].  * If you need to use an initialization vector in this manner, feel free to prepend it to the key, yourself, before  * calling setKey().  *  * [1] WEP's initialization vectors (IV's) are used in a somewhat insecure way. Since, in that protocol,  * the IV's are relatively easy to predict, an attack described by  * {@link http://www.drizzle.com/~aboba/IEEE/rc4_ksaproc.pdf Scott Fluhrer, Itsik Mantin, and Adi Shamir}  * can be used to quickly guess at the rest of the key. The following links elaborate:  *  * {@link http://www.rsa.com/rsalabs/node.asp?id=2009 http://www.rsa.com/rsalabs/node.asp?id=2009}  * {@link http://en.wikipedia.org/wiki/Related_key_attack http://en.wikipedia.org/wiki/Related_key_attack}  *  * @param String $iv  * @see Crypt_RC4::setKey()  * @access public  */ function setIV($iv) { } /**  * Sets MCrypt parameters. (optional)  *  * If MCrypt is being used, empty strings will be used, unless otherwise specified.  *  * @link http://php.net/function.mcrypt-module-open#function.mcrypt-module-open  * @access public  * @param optional Integer $algorithm_directory  * @param optional Integer $mode_directory  */ function setMCrypt($algorithm_directory = '', $mode_directory = '') {  if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT ) {   $this->mcrypt = array($algorithm_directory, $mode_directory);   $this->_closeMCrypt();  } } /**  * Encrypts a message.  *  * @see Crypt_RC4::_crypt()  * @access public  * @param String $plaintext  */ function encrypt($plaintext) {  return self::toHex($this->_crypt($plaintext, CRYPT_RC4_ENCRYPT)); } /**  * Decrypts a message.  *  * $this->decrypt($this->encrypt($plaintext)) == $this->encrypt($this->encrypt($plaintext)).  * Atleast if the continuous buffer is disabled.  *  * @see Crypt_RC4::_crypt()  * @access public  * @param String $ciphertext  */ function decrypt($ciphertext) {  $ciphertext = self::fromHex($ciphertext);  return $this->_crypt($ciphertext, CRYPT_RC4_DECRYPT); } /**  * Encrypts or decrypts a message.  *  * @see Crypt_RC4::encrypt()  * @see Crypt_RC4::decrypt()  * @access private  * @param String $text  * @param Integer $mode  */ function _crypt($text, $mode) {  if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT ) {   $keyStream = $mode == CRYPT_RC4_ENCRYPT ? 'encryptStream' : 'decryptStream';   if ($this->$keyStream === false) {    $this->$keyStream = mcrypt_module_open($this->mode, $this->mcrypt[0], MCRYPT_MODE_STREAM, $this->mcrypt[1]);    mcrypt_generic_init($this->$keyStream, $this->key, '');   } else if (!$this->continuousBuffer) {    mcrypt_generic_init($this->$keyStream, $this->key, '');   }   $newText = mcrypt_generic($this->$keyStream, $text);   if (!$this->continuousBuffer) {    mcrypt_generic_deinit($this->$keyStream);   }   return $newText;  }  if ($this->encryptStream === false) {   $this->setKey($this->key);  }  switch ($mode) {   case CRYPT_RC4_ENCRYPT:    $keyStream = $this->encryptStream;    list($i, $j) = $this->encryptIndex;    break;   case CRYPT_RC4_DECRYPT:    $keyStream = $this->decryptStream;    list($i, $j) = $this->decryptIndex;  }  $newText = '';  for ($k = 0; $k < strlen($text); $k++) {   $i = ($i + 1) & 255;   $j = ($j + $keyStream[$i]) & 255;   $temp = $keyStream[$i];   $keyStream[$i] = $keyStream[$j];   $keyStream[$j] = $temp;   $temp = $keyStream[($keyStream[$i] + $keyStream[$j]) & 255];   $newText.= chr(ord($text[$k]) ^ $temp);  }  if ($this->continuousBuffer) {   switch ($mode) {    case CRYPT_RC4_ENCRYPT:     $this->encryptStream = $keyStream;     $this->encryptIndex = array($i, $j);     break;    case CRYPT_RC4_DECRYPT:     $this->decryptStream = $keyStream;     $this->decryptIndex = array($i, $j);   }  }  return $newText; } /**  * Treat consecutive "packets" as if they are a continuous buffer.  *  * Say you have a 16-byte plaintext $plaintext. Using the default behavior, the two following code snippets  * will yield different outputs:  *  * <code>  * echo $rc4->encrypt(substr($plaintext, 0, 8));  * echo $rc4->encrypt(substr($plaintext, 8, 8));  * </code>  * <code>  * echo $rc4->encrypt($plaintext);  * </code>  *  * The solution is to enable the continuous buffer. Although this will resolve the above discrepancy, it creates  * another, as demonstrated with the following:  *  * <code>  * $rc4->encrypt(substr($plaintext, 0, 8));  * echo $rc4->decrypt($des->encrypt(substr($plaintext, 8, 8)));  * </code>  * <code>  * echo $rc4->decrypt($des->encrypt(substr($plaintext, 8, 8)));  * </code>  *  * With the continuous buffer disabled, these would yield the same output. With it enabled, they yield different  * outputs. The reason is due to the fact that the initialization vector's change after every encryption /  * decryption round when the continuous buffer is enabled. When it's disabled, they remain constant.  *  * Put another way, when the continuous buffer is enabled, the state of the Crypt_DES() object changes after each  * encryption / decryption round, whereas otherwise, it'd remain constant. For this reason, it's recommended that  * continuous buffers not be used. They do offer better security and are, in fact, sometimes required (SSH uses them),  * however, they are also less intuitive and more likely to cause you problems.  *  * @see Crypt_RC4::disableContinuousBuffer()  * @access public  */ function enableContinuousBuffer() {  $this->continuousBuffer = true; } /**  * Treat consecutive packets as if they are a discontinuous buffer.  *  * The default behavior.  *  * @see Crypt_RC4::enableContinuousBuffer()  * @access public  */ function disableContinuousBuffer() {  if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_INTERNAL ) {   $this->encryptIndex = $this->decryptIndex = array(0, 0);   $this->setKey($this->key);  }  $this->continuousBuffer = false; } /**  * Dummy function.  *  * Since RC4 is a stream cipher and not a block cipher, no padding is necessary. The only reason this function is  * included is so that you can switch between a block cipher and a stream cipher transparently.  *  * @see Crypt_RC4::disablePadding()  * @access public  */ function enablePadding() { } /**  * Dummy function.  *  * @see Crypt_RC4::enablePadding()  * @access public  */ function disablePadding() { } /**  * Class destructor.  *  * Will be called, automatically, if you're using PHP5. If you're using PHP4, call it yourself. Only really  * needs to be called if mcrypt is being used.  *  * @access public  */ function __destruct() {  if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT ) {   $this->_closeMCrypt();  } } /**  * Properly close the MCrypt objects.  *  * @access prviate  */ function _closeMCrypt() {  if ( $this->encryptStream !== false ) {   if ( $this->continuousBuffer ) {    mcrypt_generic_deinit($this->encryptStream);   }   mcrypt_module_close($this->encryptStream);   $this->encryptStream = false;  }  if ( $this->decryptStream !== false ) {   if ( $this->continuousBuffer ) {    mcrypt_generic_deinit($this->decryptStream);   }   mcrypt_module_close($this->decryptStream);   $this->decryptStream = false;  } } // @function fromHex 把十六进制数转换成字符串 function toHex($sa , $len = 0){  $buf = "";  if( $len == 0 )   $len = strlen($sa) ;  for ($i = 0; $i < $len; $i++)  {   $val = dechex(ord($sa{$i}));     if(strlen($val)< 2)     $val = "0".$val;   $buf .= $val;  }  return $buf; } // @function fromHex 把十六进制数转换成字符串  function fromHex($sa){  $buf = "";  $len = strlen($sa) ;  for($i = 0; $i < $len; $i += 2){   $val = chr(hexdec(substr($sa, $i, 2)));   $buf .= $val;  }  return $buf; }}