So for example I have a base64 encoded string and want to decode it. The length of the string is 29 characters so obviously to decode it I have to use 32 characters.
Convert.FromBase64() only allows up to 2 padding charcaters. Is there simply no case where I'd need 3 padding characters because of base64 encoding?
Please refer to base64 definition. It allows up to 2 padding characters by desing. See description here: https://en.wikipedia.org/wiki/Base64#Padding
The length of the string is 29 characters
It is impossible for a byte[] to be encoded in base64 and produce a string of 29 chars, regardless of padding. One base64 char produces 6 bits. A byte[21] has 21 x 8 = 168 bits => 168 / 6 = 28.0 base64 chars, perfect fit. A byte[22] has 22 x 8 = 176 bits => 176 / 6 = 29.33 chars, rounds up to 30 chars. No possible byte[] can produce 29 chars.
So Convert.FromBase64() correctly tells you that the data is garbage.
