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1995-01-27 - Re: CERT statement

Header Data

From: Thomas Grant Edwards <tedwards@src.umd.edu>
To: “Perry E. Metzger” <perry@imsi.com>
Message Hash: 84456458f91801d12ec01df73b544868cbbc8a335165fe4de52bcdb8e438cb78
Message ID: <Pine.SUN.3.91.950127140107.22225C-100000@thrash.src.umd.edu>
Reply To: <9501271852.AA19504@snark.imsi.com>
UTC Datetime: 1995-01-27 19:09:38 UTC
Raw Date: Fri, 27 Jan 95 11:09:38 PST

Raw message

From: Thomas Grant Edwards <tedwards@src.umd.edu>
Date: Fri, 27 Jan 95 11:09:38 PST
To: "Perry E. Metzger" <perry@imsi.com>
Subject: Re: CERT statement
In-Reply-To: <9501271852.AA19504@snark.imsi.com>
Message-ID: <Pine.SUN.3.91.950127140107.22225C-100000@thrash.src.umd.edu>
MIME-Version: 1.0
Content-Type: text/plain


On Fri, 27 Jan 1995, Perry E. Metzger wrote:

> If things are merely encrypted, an attacker can garble them without
> being caught -- I can "decrypt" random numbers into other random
> numbers if I want.  Think of an attacker trying to sabotage the
> transfer of a binary file and you'll see why you need authentication.

You certainly need some kind of encrypted secure checksum (MAC) to ensure 
message integrity.  I don't think you have to go through the 
entire authentication of the principal.  (Though as V. Gligor keeps 
showing, even if you have a MAC at the end of your data, there are still 
some kinds of integrity attacks which are possible if you are not careful 
about how MACs and encryption is used).

Now if you are talking about simple denial-of-service (detected tampering
or traffic flooding), that is another more difficult story. 

-Thomas

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