Re: [nmh-workers] mhshow: invalid BASE64 encoding in --

[Valdis Klētnieks]

On Sun, 17 Mar 2019 17:29:16 -0400, Ken Hornstein said:
> >My reading of RFC2045 says a conforming base64 decoder is allowed to toss out
> >the blanks and the '!' char and decode the rest.
> >
> >   Any characters outside of the base64 alphabet are to be ignored in
> >   base64-encoded data.
> >
> >Yeah.  That's pretty definitive. :)
>
> Oh, hm, you know you learn something new every day, and this is my new
> thing for today.  As much as I've read RFC 2045 over the years, I missed
> this!  (This is in �6.8, in case others want to look it up).

There's this other related gem a few paragraphs earlier:

   The encoded output stream must be represented in lines of no more
   than 76 characters each.  All line breaks or other characters not
   found in Table 1 must be ignored by decoding software.  In base64
   data, characters other than those in Table 1, line breaks, and other
   white space probably indicate a transmission error, about which a
   warning message or even a message rejection might be appropriate
   under some circumstances.

I'm still trying to get even a lower-case 'must be ignored' to line up with
'a rejection might be appropriate'.. :)