From: pmetzger@shearson.com (Perry E. Metzger)
Date: Thu, 24 Dec 92 08:30:25 PST
To: cypherpunks@toad.com
Subject: Re: Signing ascii text
Message-ID: <9212241539.AA23696@maggie.shearson.com>
MIME-Version: 1.0
Content-Type: text/plain



> From: mark@coombs.anu.edu.au (Mark)
> 
> >Date: Wed, 23 Dec 92 11:02:31 PST
> >From: Eric Messick <eric@parallax.com>
> 
> >It would canonicalize a file by
> >turning all sequences of white space into a single space and trimming
> >leading and trailing whitespace from the file before computing the
> >hash.
> 
> If the message contained a table of figures formatted and seperated with
> spaces then that method would destroy the readability of the table.

The notion was NOT that the text would be altered in transmition, but that
the signature would be computed on canonicalized text. No one was proposing
hacking tabs, only that a version of the text with hacked tabs be used
to compute the checksum as by hacking the tabs we will have an easy to
produce canonical format. The concern Eric presented was that this would allow
two files containing substantially different content from a computer's point
of view to MD5 the same, but he noted that this isn't a problem in
practice because humans don't get much information out of the presense of
multiple spaces versus one space.

Perry