PHP基于流的RC4加密算法实现

基于流的RC4实现。

$rc4 = new RC4(base_decode('abcdefghijklmnopqrstuv=='));$response = $rc4->encrypt('123456');
$response2 = $rc4->encrypt('123456');

因为是基于流的，response和response2的值会不一样。
想要两次加密的值一样，需要用相同的密钥实例化RC4，再去加密或解密。

具体实现如下

class RC4
{private $_s_encrypt = null;private $_s_decrypt = null;private $_password = null;private $_encrypt_offset_i = 0;private $_decrypt_offset_i = 0;private $_encrypt_offset_j = 0;private $_decrypt_offset_j = 0;public function getPassword(){return $this->_password;}public function __construct($password){$this->_password = array_values( unpack('C*', $password));$this->_s_encrypt = $this->init();$this->_s_decrypt = array_slice($this->_s_encrypt, 0, 256);}private function init(){$p = $this->_password;$j = 0;$len = count($p);$k = [];$s = [];for ($i = 0; $i < 256; $i++) {$s[$i] = $i;$k[$i] = $p[$i % $len];}for ($i = 0; $i < 256; $i++) {$j = (($j + $s[$i] + $k[$i]) & 0xff);$tmp = $s[$i];$s[$i] = $s[$j]; //交换s[i]和s[j]$s[$j] = $tmp;}return $s;}public function encrypt($buffer){$buffer = array_values(unpack('C*', $buffer));$i = 0; $j = 0; $t = 0;$end_offset = count($buffer);for ($k = 0; $k < $end_offset; $k++){$this->_encrypt_offset_i = $i = ($this->_encrypt_offset_i + 1) & 0xff;$this->_encrypt_offset_j = $j = ($this->_encrypt_offset_j + $this->_s_encrypt[$i]) & 0xff;$tmp = $this->_s_encrypt[$i];$this->_s_encrypt[$i] = $this->_s_encrypt[$j];$this->_s_encrypt[$j] = $tmp;$t = ($this->_s_encrypt[$i] + $this->_s_encrypt[$j]) & 0xff;$buffer[$k] ^= $this->_s_encrypt[$t];}array_unshift($buffer, 'C*');return call_user_func_array('pack', $buffer);}public function decrypt($buffer){$buffer = array_values(unpack('C*', $buffer));$i = 0; $j = 0; $t = 0;$end_offset = count($buffer);for ($k = 0; $k < $end_offset; $k++){$this->_decrypt_offset_i = $i = ($this->_decrypt_offset_i + 1) & 0xff;$this->_decrypt_offset_j = $j = ($this->_decrypt_offset_j + $this->_s_decrypt[$i]) & 0xff;$tmp = $this->_s_decrypt[$i];$this->_s_decrypt[$i] = $this->_s_decrypt[$j];$this->_s_decrypt[$j] = $tmp;$t = ($this->_s_decrypt[$i] + $this->_s_decrypt[$j]) & 0xff;$buffer[$k] ^= $this->_s_decrypt[$t];}array_unshift($buffer, 'C*');return call_user_func_array('pack', $buffer);}
}

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