Encrypt and decrypt a license key in PHP

Question

I need to generate a license key with a given name, product title and an expiry date. If one of my customers buys my product and uses it, he has to enter this license key.

I tried so much methods and I have no clue how to achieve this in PHP. The key should be safe for reproduction. What would be the best way to create a license key encryption and decryption in PHP?

Answer 1

The below code may help you:

function encrypt($sData, $secretKey){
    $sResult = '';
    for($i=0;$i<strlen($sData);$i++){
        $sChar    = substr($sData, $i, 1);
        $sKeyChar = substr($secretKey, ($i % strlen($secretKey)) - 1, 1);
        $sChar    = chr(ord($sChar) + ord($sKeyChar));
        $sResult .= $sChar;

    }
    return encode_base64($sResult);
} 

function decrypt($sData, $secretKey){
    $sResult = '';
    $sData   = decode_base64($sData);
    for($i=0;$i<strlen($sData);$i++){
        $sChar    = substr($sData, $i, 1);
        $sKeyChar = substr($secretKey, ($i % strlen($secretKey)) - 1, 1);
        $sChar    = chr(ord($sChar) - ord($sKeyChar));
        $sResult .= $sChar;
    }
    return $sResult;
}

function encode_base64($sData){
    $sBase64 = base64_encode($sData);
    return str_replace('=', '', strtr($sBase64, '+/', '-_'));
}

function decode_base64($sData){
    $sBase64 = strtr($sData, '-_', '+/');
    return base64_decode($sBase64.'==');
}

Here

$secretKey; // Your secret key can be anything which you only know it. So no one easily decrypt through any tool. (recommended often change the $secretKey).