PHP encryption and decryption example sharing with key_PHP tutorial

复制代码 代码如下:

$id = "http://www.jb51.net";
$token = encrypt($id, 'E', 'jb51');
echo '加密:'.encrypt($id, 'E', 'jb51');
echo '
';
echo '解密：'.encrypt($token, 'D', 'jb51');

/***************************************************** *****************
Function name: encrypt
Function function: Encrypt and decrypt string
Usage:
Encryption: encrypt('str' ,'E','qingdou');
Decryption: encrypt('Encrypted string','D','qingdou');
Parameter description:
$string : Encryption and decryption required String
$operation: Determine whether to encrypt or decrypt: E: Encryption D: Decryption
$key: Encrypted key (key);
********** *************************************************** *******/
function encrypt($string,$operation,$key='')
{
$src  = array("/","+","=");
$dist = array("_a","_b","_c");
if($operation=='D'){$string  = str_replace($dist,$src,$string);}
$key=md5($key);
$key_length=strlen($key);
$string=$operation=='D'?base64_decode($string):substr(md5($string.$key),0,8).$string;
$string_length=strlen($string);
$rndkey=$box=array();
$result='';
for($i=0;$i<=255;$i++)
{
$rndkey[$i]=ord($key[$i%$key_length]);
$box[$i]=$i;
}
for($j=$i=0;$i<256;$i++)
{
$j=($j+$box[$i]+$rndkey[$i])%256;
$tmp=$box[$i];
$box[$i]=$box[$j];
$box[$j]=$tmp;
}
for($a=$j=$i=0;$i<$string_length;$i++)
{
$a=($a+1)%256;
$j=($j+$box[$a])%256;
$tmp=$box[$a];
$box[$a]=$box[$j];
$box[$j]=$tmp;
$result.=chr(ord($string[$i])^($box[($box[$a]+$box[$j])%256]));
}
if($operation=='D')
{
if(substr($result,0,8)==substr(md5(substr($result,8).$key),0,8))
{
return substr($result,8);
}
else
{
return'';
}
}
else
{
$rdate  = str_replace('=','',base64_encode($result));
$rdate  = str_replace($src,$dist,$rdate);
return $rdate;
}
}
?>

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