Quick calculation method of addition, subtraction, multiplication and division. PHP implements rc4 encryption algorithm code.

Code

Copy code The code is as follows:

/*
* rc4 encryption algorithm
* $pwd key
* $data data to be encrypted
*/
function rc4 ($pwd, $data)/ /$pwd key $data needs to encrypt the string
{
$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;
}

The above introduces the quick calculation method of addition, subtraction, multiplication and division. PHP implements the rc4 encryption algorithm code, including the content of the quick calculation method of addition, subtraction, multiplication and division. I hope it will be helpful to friends who are interested in PHP tutorials.