C# Method like Base64String, but only alphanumeric (no plus or slash)

Question

is there any C# method that works similar to Convert.ToBase64String but doesn't generate anything except alphanumeric output?

Thanks!

Can you tell us your specific reason for not wanting the plus or slash from Base64, just out of interest? — Xiaofu, Jun 01 '09 at 04:13
I'm using the encoded string in a URL afterwards, and the random slashes are messing with my URL routing, while the + is disallowed by my IIS7 settings (the one where you can double encode with +, forgot the name). — Alex, Jun 01 '09 at 04:17

score 24 · Answer 1 · answered Mar 01 '13 at 23:20

24

The answers are a bit outdated now. For the benefit of future searchers: The best way to handle this now in C# is:

byte[] b; // fill your byte array somehow
string s = System.Web.HttpServerUtility.UrlTokenEncode(b);

This returns a Base64-encoded string that is URL-safe (which is what you said you were really after in the comments to your question).

You can then decode it again using, you guessed it:

byte[] b = System.Web.HttpServerUtility.UrlTokenDecode(s);

answered Mar 01 '13 at 23:20

Mason G. Zhwiti

6,444
11
61
97

Always ends with a 0 for some reason. – Hele Nov 12 '16 at 19:13
@Hele are you saying the code doesn't work? I.e. I don't understand why it matters if your encoded strings end in 0. – Mason G. Zhwiti Nov 12 '16 at 20:33
@Hele What does base64 encoding have to do with generating random strings? – Mason G. Zhwiti Nov 12 '16 at 22:48
Just saying it's a waste. Why is it there? – Hele Nov 12 '16 at 22:54
@Hele My guess is whatever you're encoding simply has the trait that it ends with zeros when encoded in base64. If you try different strings with different lengths, you may get a different result. – Mason G. Zhwiti Nov 14 '16 at 22:50

score 14 · Accepted Answer · edited May 23 '17 at 12:34

14

You're probably looking at using something like Base32 encoding then. There is a Base32 encoder/decoder for C# here by Michael Giagnocavo. It uses a combination of capitalized letters and numbers.

There's also a related discussion on StackOverflow here.

EDIT: And if by any chance this is for URL-safe related Base64 encoding, just do Base64 and replace "+" with "-" and "/" with "_". But I'm guessing, you may not want it for that.

edited May 23 '17 at 12:34

Community

1
1

answered Jun 01 '09 at 04:12

Xiaofu

15,523
2
32
45

Base64 will never create "-" or "_" by itself? – Alex Jun 01 '09 at 04:24
The method provided by the .NET libraries doesn't, no. – Xiaofu Jun 01 '09 at 04:27
2

There's a brief description on URL-safe Base64 here: http://en.wikipedia.org/wiki/Base64#URL_applications – Xiaofu Jun 01 '09 at 04:34

score 3 · Answer 3 · answered Jun 01 '09 at 04:22

3

A common variant of base-64 (for use on query-string) is to use '-' and '_' in place of '+' and '/'. Perhaps a bit of Replace(...) at each end would do the job?

answered Jun 01 '09 at 04:22

Marc Gravell

1,026,079
266
2,566
2,900

I thought Base64 would encode by itself to "-" and "_" as well. I guess it doesn't?? – Alex Jun 01 '09 at 04:25
3

No; the "classic" base-64 set is "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" – Marc Gravell Jun 01 '09 at 04:30

score 2 · Answer 4 · answered Jun 01 '09 at 04:00

2

you can replace + or slash with some predefined string if possible.

answered Jun 01 '09 at 04:00

TheVillageIdiot

40,053
20
133
188

1

I thought about doing that, but if I happen to hit that exact string during regular base64 encoding then hell breaks loose. Plus it would be really just a hack. :( – Alex Jun 01 '09 at 04:09
@Alex it is not a hack. It is used in communications. I really not remember the exact scheme (that's why such short answer) but it is possible to handle the occurrence of pattern in base64 string gracefully. I've read about it in AST's "Computer Network" and Stalling's "Data and Computer Communications" during my masters. – TheVillageIdiot Jun 01 '09 at 04:25
Got it. Didn't know about "-" and "_" by the way - that works I guess. Thanks so much though! :) – Alex Jun 01 '09 at 04:29

score 1 · Answer 5 · answered Sep 15 '16 at 16:14

1

I was searching for a such like encoder and I used https://github.com/renmengye/base62-csharp/

It's an encoder/decoder in "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" character space range.

I just wrapped its methods with

System.Text.Encoding.UTF8.GetBytes(plainText); and System.Text.Encoding.UTF8.GetString(decoded);

calls to allow it to work easily with strings.

answered Sep 15 '16 at 16:14

AFract

8,868
6
48
70

1

Yes! This is what I'm looking for. Not for URL's, though - just representing a string of bytes in an easy copy/pasteable way. – pettys Apr 02 '21 at 19:38

score 0 · Answer 6 · answered Jun 01 '09 at 04:35

0

You can use BitConverter.ToString() which will give you a hex string. However the resulting strings will be longer than Base64 encoding.

answered Jun 01 '09 at 04:35

sharptooth

167,383
100
513
979

C# Method like Base64String, but only alphanumeric (no plus or slash)

6 Answers6

Linked