[ruby-core:54418] [ruby-trunk - Bug #8286] Can't decode non-MIME Base64

Issue #8286 has been updated by adacosta (Alan Da Costa).


Hi Naruse, thank you for looking at my issue and sorry for wasting your time. I should have spent more time verifying my code.
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Bug #8286: Can't decode non-MIME Base64
https://bugs.ruby-lang.org/issues/8286#change-38684

Author: adacosta (Alan Da Costa)
Status: Rejected
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: 2.0.0-p0
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


=begin
In https://github.com/ruby/ruby/blob/trunk/lib/base64.rb#L42 , RFC 2045 is mentioned for encode64/decode64 support, which is the MIME RFC. I don't believe this is the correct RFC to reference, as RFC 4648 is the correct RFC for Base64. Further, RFC 4648 has an explicit section about Line Feeds in Encoded Data, http://tools.ietf.org/html/rfc4648#section-3.1 . This section states:

   MIME [4] is often used as a reference for base 64 encoding.  However,
   MIME does not define "base 64" per se, but rather a "base 64 Content-
   Transfer-Encoding" for use within MIME.  As such, MIME enforces a
   limit on line length of base 64-encoded data to 76 characters.  MIME
   inherits the encoding from Privacy Enhanced Mail (PEM) [3], stating
   that it is "virtually identical"; however, PEM uses a line length of
   64 characters.  The MIME and PEM limits are both due to limits within
   SMTP.

   Implementations MUST NOT add line feeds to base-encoded data unless
   the specification referring to this document explicitly directs base
   encoders to add line feeds after a specific number of characters.


In my case, I have a separate implementation that has not added line feeds to the Base64 (non-MIME) and as a result, Base64.decode64 can not decode the non-MIME encoded data. I believe this also indicates Base64#encode64 has the wrong behavior of MIME encoding Base64.

I have an example of the issue at https://github.com/adacosta/base64_compatible/blob/master/test/test_coding.rb#LC25 .
=end


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