php rc4可加密解密函数

php rc4可加密解密函数整理。

/**
 * Crypt/decrypt strings with RC4 stream cypher algorithm.
 *
 * @param string $key Key
 * @param string $data Encripted/pure data
 * @see   http://pt.wikipedia.org/wiki/RC4
 * @return string
 */
function rc4($key, $data) {
    // Store the vectors "S" has calculated
    static $SC;
    // Function to swaps values of the vector "S"
    $swap = function (&$v1, &$v2) {
        $v1 = $v1 ^ $v2;
        $v2 = $v1 ^ $v2;
        $v1 = $v1 ^ $v2;
    };
    $ikey = crc32($key);
    if (!isset($SC[$ikey])) {
        // Make the vector "S", basead in the key
        $S = range(0, 255);
        $j = 0;
        $n = strlen($key);
        for ($i = 0; $i < 255; $i++) {
            $char = ord($key{$i % $n});
            $j = ($j + $S[$i] + $char) % 256;
            $swap($S[$i], $S[$j]);
        }
        $SC[$ikey] = $S;
    } else {
        $S = $SC[$ikey];
    }
    // Crypt/decrypt the data
    $n = strlen($data);
    $data = str_split($data, 1);
    $i = $j = 0;
    for ($m = 0; $m < $n; $m++) {
        $i = ($i + 1) % 256;
        $j = ($j + $S[$i]) % 256;
        $swap($S[$i], $S[$j]);
        $char = ord($data[$m]);
        $char = $S[($S[$i] + $S[$j]) % 256] ^ $char;
        $data[$m] = chr($char);
    }
    return implode('', $data);
}

使用方法：

秘钥 : ENCRYPT_KEY = 'n01nemN0KsIHytH6skEo';
明文(原文) : $data = 'type=php&id=2';
密文(加密后) :

$ciphertext = urlencode(base64_encode(rc4(ENCRYPT_KEY, $data . '&len=' . strlen($data))));

明文(解密后) :

$originaltext = rc4(ENCRYPT_KEY, base64_decode($ciphertext));