[lug] Recovering a Mime/base64 encoded file

[Eric Kilfoil]

ROT13 is much different than base64 encoding.  ROT13 is an "encryption"
method for modifying plaintext characters.  All it does it rotate the
character value by 13 (hence rot13).

For example, A become M, B becomes N, C becomes O, M becomes Z.  (this may
not be conversion, but you should get the jist of it).  Linux used to come
with utilities to do rot 13.  It actually become part of the standard BSD
games package :).

Base64 takes binary data and converts it from a base 2 representation to a
base 64 representation, which is much different than rot13 obviously.

There are problems available which do base64 decoding.  They are also
fairly easy to write.

Here is software to do this task:

http://freshmeat.net/projects/base64/

Regards,

Eric Kilfoil
Sr. UNIX Systems Engineer
ViaWest Internet Services

On Fri, 25 May 2001, D. Stimits wrote:

> There is an option in Netscape which shows up if you right click,
> "Unscramble (ROT13)" while over the email text, which might be what you
> need (use the option twice to put it back the way it was if you don't
> like the results). Don't know if that would work, or if you are using
> Netscape.
>
> D. Stimits, stimits at idcomm.com
>
> John Karns wrote:
> >
> > On a few ocassions I have come across situations where I would like to
> > recover a base-64 encoded file segment, but have given up.  In the latest
> > case, I have a segment that begins:
> >
> > --part1_62.cda3349.27e8448b_boundary
> > Content-Type: text/plain; charset="US-ASCII"
> > Content-Transfer-Encoding: 7bit
> >
> > --part1_62.cda3349.27e8448b_boundary
> > Content-Type: image/jpeg; name="pic.jpg"
> > Content-Transfer-Encoding: base64
> > Content-Disposition: inline; filename="pic.jpg"
> >
> > /9j/4AAQSkZJRgABAgEASABIAAD/7RGeUGhvdG9zaG9wIDMuMAA4QklNA+0AAAAAABAASAAA
> > AAEAAQBIAAAAAQABOEJJTQQNAAAAAAAEAAAAeDhCSU0D8wAAAAAACAAAAAAAAAAAOEJJTQQK
> > AAAAAAABAAA4QklNJxAAAAAAAAoAAQAAAAAAAAACOEJJTQP1AAAAAABIAC9mZgABAGxmZgAG
> > AAAAAAABAC9mZgABAKGZmgAGAAAAAAABADIAAAABAFoAAAAGAAAAAAABADUAAAABAC0AAAAG
> >
> > [snip]
> >
> > ... and ends thus:
> >
> > VdirsVdirsVdirsVdirsVdirsVdirsVdirsVdirsVdirsVdirsVdirsVdirsVdirsVdirsVd
> > irsVdirsVdirsVdirsVdirsVdirsVdirsVdirsVdirsVdirsVdirsVdirsVdirsVdirsVdir
> > sVdirsVdirsVdirsVf/Z
> >
> > --part1_62.cda3349.27e8448b_boundary--
> >
> > Can anyone offer suggestions on a method to decode this to a binary (in
> > this case) .jpg?
> >
> > ----------------------------------------------------------------------
> > John Karns                                              jkarns at csd.net
> >
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