1993-09-19 - Definition of “Zero Knowledge”

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From: tcmay@netcom.com (Timothy C. May)
To: cypherpunks@toad.com
Message Hash: c5303b34324b493e31f6bcb77a130f4b1fd0ea5d9c8d1d34bcc6f9e1f71f5e34
Message ID: <9309190335.AA22435@netcom5.netcom.com>
Reply To: <m0oeF8h-00021LC@khijol>
UTC Datetime: 1993-09-19 03:36:39 UTC
Raw Date: Sat, 18 Sep 93 20:36:39 PDT

Raw message

From: tcmay@netcom.com (Timothy C. May)
Date: Sat, 18 Sep 93 20:36:39 PDT
To: cypherpunks@toad.com
Subject: Definition of "Zero Knowledge"
In-Reply-To: <m0oeF8h-00021LC@khijol>
Message-ID: <9309190335.AA22435@netcom5.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain

> > Not necessarily. Zero knowledge proof techniques, for instance, can be
> > applied to make source code as impenetrable as one wishes. This tends to
> > carry a heavy runtime overhead, of course.
> Could you go into more detail on this?  Thanks!
> -- 
> Ed Carp, N7EKG			erc@apple.com			510/659-9560

I didn't write the item above, but I'll add my comments anyway.

Zero knowledge interactive proof systems are a critical part of modern
crypto. Here's the brief summary from the Cypherpunks Glossary,
available by anon. ftp at soda.berkeley.edu in pub/cypherpunks/misc as

***     zero knowledge proofs -- proofs in which no 
knowledge of the actual proof is conveyed. Peggy the Prover 
demonstrates to Sid the Skeptic that she is indeed in 
possession of some piece of knowledge without actually 
revealing any of that knowledge. This is useful for access to 
computers, because eavesdroppers or dishonest sysops cannot 
steal the knowledge given. Also called minimum disclosure 
proofs. Useful for proving possession of some property, or 
credential, such as age or voting status, without revealing 
personal information.

By the way, this Glossary was distributed at the very first
Cypherpunks meeting, a year ago. While never intended as an FAQ, it
still may be of value to subscribers here.

-Tim May

Timothy C. May         | Crypto Anarchy: encryption, digital money,  
tcmay@netcom.com       | anonymous networks, digital pseudonyms, zero
408-688-5409           | knowledge, reputations, information markets, 
W.A.S.T.E.: Aptos, CA  | black markets, collapse of governments.
Higher Power: 2^756839 | Public Key: PGP and MailSafe available.
Note: I put time and money into writing this posting. I hope you enjoy it.