Passing base64 to URL in PHP to decode with OpenSSL - php

Question

I'm trying to pass an argument via URL. This argument is base64.
https://site/file?base=+EOOJZIWLfQwoiVT6rfDbj3sr9vabuzX84bcT38u9hQSW3d/ErsE9E2OlXRvc88x
To decrypt it in PHP file with OpenSSL. When I send it, in PHP file it becomes
"EOOJZIWLfQwoiVT6rfDbj3sr9vabuzX84bcT38u9hQSW3d/ErsE9E2OlXRvc88x"
It escapes " + " in base64.
So OpenSSL can't decrypt it, because it gets the wrong base64. I tried urlencode, but it escapes " / " to " %2f" so same here.
This is my code:
$user = urlencode($_GET['base64']); // user
$key = ('12345678901234567890123456789012');
$iv = ('1234567890123456');
$field_data = htmlspecialchars($user);
//$e = urldecode($field_data);
$output = openssl_decrypt($field_data, 'AES-256-CBC', $key, 0, $iv);

Answer 1

Solved by insted of encode with base64 do it with base64-url encode and decode it in php by base64 decode thats make it return to normal base64 .. then pass it to openssl
$user = $_GET['x']; // user
function base64url_encode($data) {
return rtrim(strtr($data, '+/', '-_'), '=');
}
function base64_url_decode($input) {
return strtr($input, '._-', '+/+');
}
$last = base64_url_decode ( $user);
$key = ('12345678901234567890123456789012');
$iv = ('1234567890123456');
$output = openssl_decrypt($last, 'AES-256-CBC', $key, 0, $iv);
where url passed is
https://site/file?base=-EOOJZIWLfQwoiVT6rfDbj3sr9vabuzX84bcT38u9hQSW3d_ErsE9E2OlXRvc88x
i used client side c++ for encrypt aes and base64 url