PHP的RC4加密算法

function rc4 ($pwd, $data)//$pwd密钥　$data需加密字符串

{

$key[] =””;

$box[] =””;

$pwd_length = strlen($pwd);

$data_length = strlen($data);

for ($i = 0; $i < 256; $i++)

{

$key[$i] = ord($pwd[$i % $pwd_length]);

$box[$i] = $i;

}

for ($j = $i = 0; $i < 256; $i++)

{

$j = ($j + $box[$i] + $key[$i]) % 256;

$tmp = $box[$i];

$box[$i] = $box[$j];

$box[$j] = $tmp;

}

for ($a = $j = $i = 0; $i < $data_length; $i++)

{

$a = ($a + 1) % 256;

$j = ($j + $box[$a]) % 256;

$tmp = $box[$a];

$box[$a] = $box[$j];

$box[$j] = $tmp;

$k = $box[(($box[$a] + $box[$j]) % 256)];

$cipher .= chr(ord($data[$i]) ^ $k);

}

return $cipher;

}

$key = ‘mykey’;
$string = ‘iloveyou’;

echo $after = rc4($key, $string);// 加密
echo $befor = rc4($key, $after);解密