From: tcmay@got.net (Timothy C. May)
Date: Thu, 15 Feb 1996 18:25:12 +0800
To: Michael Froomkin <cypherpunks@toad.com>
Subject: Re: anonymous age credentials, sharing of
Message-ID: <ad47e0d10b0210043ce0@[205.199.118.202]>
MIME-Version: 1.0
Content-Type: text/plain


At 7:38 PM 2/14/96, Michael Froomkin wrote:
>Suppose Alice is a CA who issues anonymous age credentials.
>Bob is 15
>Carol is 25
>
>Carol gets a legitimate anonymous age credential from Alice bound to an
>anonymous public key generated for this purpose.  Carol then gives the
>key pair to Bob.  Bob uses to do things only adults are legally permitted
>to do.  (It's not bound to Carol's everday keypair because that's not
>anonymous....)
>
>What can stop Bob and Carol from subverting a scheme that relies on
>anonymous age creditials in this manner?

Nothing, except biometric methods (fingerprints, retinal scans, electronic
signatures (the pen type), DNA, etc.) That is, if the credential is
transferrable by transfer (not a syllogism), then it can be transferred.
If, however, the credential needs some input from a local biometric input
device, then this makes it harder to transfer the credential.

Unless the biometric device is bypassed....

(Likewise, Carol could log on to the illegal activity and "let Bob watch."
Another form of bypassing viewing credentials.)

>If the answer is "nothing" this might mean that purveyors of "adult"
>material might have no defense against a law requiring that they collect a
>True Name + age creditential....

There are interesting questions here....mostly I think of the "True Name"
as only another credential, but this is a complicated argument to make, and
I don't have the time right now.

(Also, Perry is even now composing a "what does this have to do with
cryptography?" perrygram.)

--Tim May

Boycott espionage-enabled software!
We got computers, we're tapping phone lines, we know that that ain't allowed.
---------:---------:---------:---------:---------:---------:---------:----
Timothy C. May              | Crypto Anarchy: encryption, digital money,
tcmay@got.net  408-728-0152 | anonymous networks, digital pseudonyms, zero
W.A.S.T.E.: Corralitos, CA  | knowledge, reputations, information markets,
Higher Power: 2^756839 - 1  | black markets, collapse of governments.
"National borders aren't even speed bumps on the information superhighway."