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<?php
/*
* Allows encrypt and decrypt
*/
class Crypt {
/**
* Gets a random value for encryption
* - From php.net docs
*
* @param $iv_len
* length of random variable
*/
function getRndIV($iv_len) {
$iv = '';
while ($iv_len-- > 0) {
$iv .= chr(mt_rand() & 0xff);
}
return $iv;
}
/**
* Encrypts string
* - From php.net docs
*
* @param $str
* string to encrypt
* @param $salt
* password to use for encryption
* @param $iv_len
* length of random number
*/
function encrypt($str, $salt, $iv_len = 16) {
$str .= "\x13";
$n = strlen($str);
if ($n % 16) $str .= str_repeat("\0", 16 - ($n % 16));
$i = 0;
$enc_text = $this->getRndIV($iv_len);
$iv = substr($salt ^ $enc_text, 0, 512);
while ($i < $n) {
$block = substr($str, $i, 16) ^ pack('H*', md5($iv));
$enc_text .= $block;
$iv = substr($block . $iv, 0, 512) ^ $salt;
$i += 16;
}
return urlencode(base64_encode($enc_text));
}
/**
* Decrypts string
* - From php.net docs
*
* @param $enc
* encrypted string to decrypt
* @param $salt
* password to use for encryption
* @param $iv_len
* length of random number
*/
function decrypt($enc, $salt, $iv_len = 16) {
$enc = urldecode(base64_decode($enc));
$n = strlen($enc);
$i = $iv_len;
$str = '';
$iv = substr($salt ^ substr($enc, 0, $iv_len), 0, 512);
while ($i < $n) {
$block = substr($enc, $i, 16);
$str .= $block ^ pack('H*', md5($iv));
$iv = substr($block . $iv, 0, 512) ^ $salt;
$i += 16;
}
return preg_replace('/\\x13\\x00*$/', '', $str);
}
}
?>
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