1993-12-14 - Re: Signing pictures – how hard, how long?

Header Data

From: szabo@netcom.com (Nick Szabo)
To: pcw@access.digex.net (Peter Wayner)
Message Hash: 1d1ca2dadb5c30c3a8252036f43c575650e3e6e05830a2cdb47808fb810b4b08
Message ID: <199312142006.MAA29406@mail.netcom.com>
Reply To: <199312141803.AA28396@access.digex.net>
UTC Datetime: 1993-12-14 20:10:29 UTC
Raw Date: Tue, 14 Dec 93 12:10:29 PST

Raw message

From: szabo@netcom.com (Nick Szabo)
Date: Tue, 14 Dec 93 12:10:29 PST
To: pcw@access.digex.net (Peter Wayner)
Subject: Re: Signing pictures -- how hard, how long?
In-Reply-To: <199312141803.AA28396@access.digex.net>
Message-ID: <199312142006.MAA29406@mail.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain



Peter Wayner:
> I think signing photographs and movie images is a difficult
> problem. Why? Because one flipped bit will completely screw
> up the hash function.

Is a one-way hash function or digital signature possible with the
following property: signature verification doesn't just determine
the boolean altered vs. pristine, but also shows the picture
distance between the altered and original?  Forgery may often
require an editing distance much greater than the error rate
from media noise or lossy compression.

Nick Szabo				szabo@netcom.com




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