C# to PHP base64 encode/decode.

Question

So I have this c# application that needs to ping my web server thats running linux/php stack.
I am having problems with the c# way of base 64 encoding bytes.

my c# code is like:

byte[] encbuff = System.Text.Encoding.UTF8.GetBytes("the string");
String enc = Convert.ToBase64String(encbuff);

and php side:

$data = $_REQUEST['in'];
$raw = base64_decode($data);

with larger strings 100+ chars it fails. I think this is due to c# adding '+'s in the encoding but not sure. any clues

Answer 1

Convert.ToBase64String doesn't seem to add anything extra as far as I can see. For instance:

byte[] bytes = new byte[1000];
Console.WriteLine(Convert.ToBase64String(bytes));

The above code prints out a load of AAAAs with == at the end, which is correct.

My guess is that $data on the PHP side doesn't contain what enc did on the C# side - check them against each other.

Answer 2

Note that + is a valid character in base64 encoding, but when used in URLs it is often translated back to a space. This space may be confusing your PHP base64_decode function.

You have two approaches to solving this problem:

• Use %-encoding to encode the + character before it leaves your C# application.
• In your PHP application, translate space characters back to + before passing to base64_decode.

The first option is probably your better choice.

Answer 3

in c#

this is a <B>long</b>string. and lets make this a3214 ad0-3214 0czcx 909340 zxci 0324#$@#$%%13244513123

turns into

dGhpcyBpcyBhIDxCPmxvbmc8L2I+c3RyaW5nLiBhbmQgbGV0cyBtYWtlIHRoaXMgYTMyMTQgYWQwLTMyMTQgMGN6Y3ggOTA5MzQwIHp4Y2kgMDMyNCMkQCMkJSUxMzI0NDUxMzEyMw==

for me. and i think that + is breaking it all.

Answer 4

You should probably URL Encode your Base64 string on the C# side before you send it.

And URL Decode it on the php side prior to base64 decoding it.

C# side

byte[] encbuff = System.Text.Encoding.UTF8.GetBytes("the string");
string enc = Convert.ToBase64String(encbuff);
string urlenc = Server.UrlEncode(enc);

and php side:

$data = $_REQUEST['in'];
$decdata = urldecode($data);
$raw = base64_decode($decdata);

Answer 5

The PHP side should be: $data = $_REQUEST['in']; // $decdata = urldecode($data); $raw = base64_decode($decdata);

The $_REQUEST should already be URLdecoded.