From: yanek@novavax.nova.edu (Yanek Martinson)
Date: Thu, 24 Dec 92 11:13:41 PST
To: pmetzger@shearson.com
Subject: significance of spaces
Message-ID: <9212241912.AA15402@novavax.nova.edu>
MIME-Version: 1.0
Content-Type: text/plain


> 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.

This is true for most text, like this message.  But sometimes people
send messages where spacing is VERY important:

This is especially true of tables such as this one:


Name	Yes	No

Smith	X
Jones		X
Brown		X
Xyzzy	X

If the signature algorithm disregarded spaces, the X's could be moved
from one column to the other without affecting the signature.

I know that this information COULD have been represented as:

Smith	Yes
Jones	No
Brown	No
Xyzzy	Yes

But sometimes people use the other format.  Another solution is to
surround all significant spaces with some other character, such 
as the vertical bar:

|Name	| Yes	| No	|

|Smith	| X	|	|
|Jones	|	| X	|
|Brown	|	| X	|
|Xyzzy	| X	|	|

If this were done, an X could not be moved without affecting the signature
even if tabs/spaces were insignificant.

The point is that if whitespace is made insignificant, the users must be
educated about it, and trained to use one of the two last formats
instead of the first one.  


--
Yanek Martinson    mthvax.cs.miami.edu!safe0!yanek     uunet!medexam!yanek
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