Remove base64 encoded trailing character

hankcoder has asked for the wisdom of the Perl Monks concerning the following question:

Hi, in base64 encoded string, I would like to know if there are any future conflict or any complication if I remove encoded strings that ends with equal characters "=" ?

I'm using MIME::Base64, encode_base64($str,"");

For some strings after encoded will have trailing equal character(s). Some with 1 characters some with 2 characters. I have tested myself by removing all equal characters and decode it back without any problem.

I just would like to seek for experienced guru here is it ok if I completely remove all equal characters in base64 encoded string?

Also I'm not quite understand of 65-character subset ([A-Za-z0-9+/=]). Does this means the encoded strings will contain such characters?

I understand A-Za-z0-9, but +/= means what characters?

Thanks.

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Re: Remove base64 encoded trailing character by Corion (Patriarch) on Mar 26, 2016 at 18:00 UTC
The `=` characters at the end are padding, because Base64 can only encode strings that have a length that is a multiple of 3 characters.	[reply] [d/l]
Re^2: Remove base64 encoded trailing character by hankcoder (Scribe) on Mar 26, 2016 at 18:09 UTC
Corion, thank you for pointing it out. I understand now. so the following: `123 -> MTIz 1234 -> MTIzNA== 12345 -> MTIzNDU= 123456 -> MTIzNDU2` [download] Just to confirm, when Decode back, it doesn't matter the encoded strings has "=" or not right? In that case I can safely remove all encoded padding = yes?	[reply] [d/l]
Re^3: Remove base64 encoded trailing character by FreeBeerReekingMonk (Deacon) on Mar 26, 2016 at 18:21 UTC
Read Base64#Padding In theory, the padding character is not needed for decoding, since the number of missing bytes can be calculated from the number of Base64 digits. In some implementations, the padding character is mandatory, while for others it is not used. One case in which padding characters are required is concatenating multiple Base64 encoded files. Oh and: If you want to encode a large file, you should encode it in chunks that are a multiple of 57 bytes. This ensures that the base64 lines line up and that you do not end up with padding in the middle. Read the source for more: Base64.pm	[reply]
Re^4: Remove base64 encoded trailing character by hankcoder (Scribe) on Mar 27, 2016 at 17:50 UTC