php实现的rc4加密解密类定义与用法示例

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,''); } $newText = mcrypt_generic($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: * * * echo $rc4->encrypt(substr($plaintext,8)); * echo $rc4->encrypt(substr($plaintext,8,8)); * * * echo $rc4->encrypt($plaintext); * * * The solution is to enable the continuous buffer. Although this will resolve the above discrepancy,it creates * another,as demonstrated with the following: * * * $rc4->encrypt(substr($plaintext,8)); * echo $rc4->decrypt($des->encrypt(substr($plaintext,8))); * * * echo $rc4->decrypt($des->encrypt(substr($plaintext,8))); * * * 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; } }

setKey('21sd54a1w5q'); $text = 'www.jb51.cc'; echo $x = $rc4->encrypt($text);//加密 echo '
'; echo $rc4->decrypt( $x) ;//解密