From: baum@newton.apple.com (Allen J. Baum)
To: cypherpunks@toad.com
Message Hash: 19e1ce90d6713628ce285baf935c0fb08b567cac59f943bcca27d3af0825fe67
Message ID: <9402241808.AA05601@newton.apple.com>
Reply To: N/A
UTC Datetime: 1994-02-24 18:40:38 UTC
Raw Date: Thu, 24 Feb 94 10:40:38 PST
From: baum@newton.apple.com (Allen J. Baum)
Date: Thu, 24 Feb 94 10:40:38 PST
To: cypherpunks@toad.com
Subject: Re: Digitally Signing Physical Objects
Message-ID: <9402241808.AA05601@newton.apple.com>
MIME-Version: 1.0
Content-Type: text/plain
>> 3. The shop or customer wishing to authenticate the part takes the
>> number stamped on the part, runs it through the *public* key of the
>> manufacturer (widely available, not kept secret, of course) and gets
>> back the feature vector, which he can then compare to what he actually
>> sees on the object.
....
>This seems to have a tricky dependence on the tolerance. The forger can
>get a valid plaintext and signed feature vector. So, if the tolerance
>for error is too low, you get false positives, but if it's too high, a
>forger could create something starting from the feature vector. An
>interesting CAD/CAM problem.
To keep black market forgery part off the market, a 30% tolerance is way
more than enough. There should be no false negatives (making a real part
look fake), but if 1/3 of the forgeries slip through (i.e. 2/3 don't), this
has the affect of driving the forgery price up by a factor of 3,
effectively pricing them out of the market. (Unless the real goods are
overpriced a factor of 3...:-)
**************************************************
* Allen J. Baum tel. (408)974-3385 *
* Apple Computer, 20525 Mariani Ave, MS 305-3B *
* Cupertino, CA 95014 baum@apple.com *
**************************************************
Return to February 1994
Return to “baum@newton.apple.com (Allen J. Baum)”
1994-02-24 (Thu, 24 Feb 94 10:40:38 PST) - Re: Digitally Signing Physical Objects - baum@newton.apple.com (Allen J. Baum)