From: "James A. Donald" <jamesd@netcom.com>
Date: Thu, 12 Jan 95 10:09:07 PST
To: Jonathan Rochkind <jrochkin@cs.oberlin.edu>
Subject: Re: How do I know if its encrypted?
In-Reply-To: <ab3a75370402100421a8@[132.162.201.201]>
Message-ID: <Pine.3.89.9501121007.A15243-0100000@netcom10>
MIME-Version: 1.0
Content-Type: text/plain


On Thu, 12 Jan 1995, Jonathan Rochkind wrote:
 
> Of course, we're not just dealing with text.  So the scheme has got to be
> changed a bit so as to be able to detect unencrypted GIFs, and mu-law
> files, and as yet to be determined unknown files.  I don't know enough
> about what's being talked about to know if this entropy detecting stuff
> will generalize to non text files.

Graphics files are already compressed, so they pass the entropy 
test, but they start with a distinctive header.

The best way to stop graphics would be a volume limit per 
apparent source and per apparent destination.

To program that is a bit like hard work.

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