Php openSLL Encryption - to prevent special characters - php

Question

I want to create and encryption for get variabile passed in url and for asynchronous call
for example:
$textToEncrypt = "Hello World";
$encryptionMethod = "AES-256-CBC";
$secretHash = "cVb67YtfAz328oOikl96vBn";
$iv = "adfrf54dmnlo09ax";
$encryptedText = openssl_encrypt($textToEncrypt,$encryptionMethod,$secretHash, 0, $iv);
result is: W2p0S2qlSierJnIcA/AM3g==
there are some special characters, == always at the end. I want to prevent this! How can I output only 0-9 and A-Z and a-z characters?
thanks

Answer 1

I had the same issue. I wanted to remove the special characters. So, this is what I did. Convert the encrypted text into hex value using base64_encode($encryptedText). So, there will be no special characters. Then for the revert, use base64_decode before passing to openssl_decrypt.

Answer 2

$ciphering = "AES-128-CTR";
use this as your cipher string, it'll remove any type of == from the end

Answer 3

I notice I had exactly 2 equal signs at the end of my encrypted string too. It seems theres always 2 equal signs at the end. Here's my solution
function encryptString($string, $action, $baseIP = 'false', $extraKey = ''){
global $flag;
$encryptedIP = '';
if($baseIP){
$encryptedIP = encryptString($_SERVER['REMOTE_ADDR'], 'encrypt', false);
}
$output = false;
$encrypt_method = "AES-256-CBC";
$secret_key = $flag['2nd-encrypt-key'].$encryptedIP.'-'.$extraKey;
$secret_iv = $flag['2nd-encrypt-secret'].$encryptedIP.'-'.$extraKey;
$key = hash('sha256', $secret_key);
$iv = substr(hash('sha256', $secret_iv), 0, 16);
$output;
if($action == 'encrypt'){
$output = openssl_encrypt($string, $encrypt_method, $key, 0, $iv);
$output = base64_encode($output);
//replace equal signs with char that hopefully won't show up
$output = str_replace('=', '[equal]', $output);
}else if($action == 'decrypt'){
//put back equal signs where your custom var is
$setString = str_replace('[equal]', '=', $string);
$output = openssl_decrypt(base64_decode($setString), $encrypt_method, $key, 0, $iv);
}
return $output;
}