What is the difference between Convert.ToBase64String(byte[]) and HttpServerUtility.UrlTokenEncode(byte[])?

Question

I\'m trying to remove a dependence on System.Web.dll from a Web API project, but have stumbled on a call to HttpServerUtility.UrlTokenEncode(byte[] input) (and its

Answer 1

I took DGibbs on their word and Used the Source. It turns out the following happens in the HttpServerUtility methods:

Encoding to Base64

1. Use System.Convert to convert the input to Base64.

2. Replace + by - and / by _. Example: Foo+bar/=== becomes Foo-bar_===.

3. Replace any number of = at the end of the string, with an integer denoting how many they were. Example: Foo-bar_=== becomes Foo-bar_3.

Decoding from Base64

1. Replace the digit at the end of the string by the same number of = signs. Example: Foo-bar_3 becomes Foo-bar_===.

2. Replace - by + and _ by /. Example: Foo-bar_=== becomes Foo+bar/===.

3. Use System.Convert to decode the preprocessed input from Base64.

Answer 2

HttpServerUtility.UrlTokenEncode(byte[] input) will encode a URL safe Base64 string. In Base64 +, / and = characters are valid, but they are not URL safe, this method will replace these characters whereas the Convert.ToBase64String(byte[] input) will not. You can probably drop the reference and do it yourself.

Usually, '+' is replaced with '-' and '/' with '_' padding '=' is just removed.

Accepted answer here gives a code example: How to achieve Base64 URL safe encoding in C#?