Teepe, Wouter

English

ARTS repository - University of Groningen

   University of GroningenNew Protocols for Proving Knowledge of Arbitrary Secrets While not Giving Them AwayTeepe, WouterIMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:2005Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Teepe, W. (2005). New Protocols for Proving Knowledge of Arbitrary Secrets While not Giving Them Away.s.n.CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 06-06-2022New Protocols forProving Knowledge of Arbitrary SecretsWhile not Giving Them AwayWouter TeepeArtificial Intelligence, University of Groningen,Grote Kruisstraat 2/1, 9712 TS Groningen, The Netherlands,email: w.g.teepe@ai.rug.nlAbstractThis paper introduces and describes new protocols for proving knowledgeof secrets without giving them away: if the verifier does not know the secret,he does not learn it [1]. An implementation van be found in this volume [2].1 Introduction: Proving SecretsIn application domains where sensitive information plays an important role, suchas police research, intelligence, finance and the medical domain, one may wantto ask whether someone knows a specific fact. Because of the sensitivity of theinformation concerned, it is often undesirable for the specific fact itself to be toldby way of posing the question. For example posing the question “Did you knowthat Geertje is pregnant?” will inform the asked person about a fact. If it is theaim to ask this very question without informing the asked person about the fact,we need dedicated protocols for asking such questions in a multi-agent context.In these protocols, we recognise a prover and a verifier. Three role configu-rations exist for this type of protocols: (1) the prover may want to pro-activelyprove knowledge of a secret, (2) a verifier may ask someone to prove knowledge ofa secret, or (3) two players may mutually prove knowledge of a secret.In essence, these protocols consist of the verifier asking the prover to modifythe secret in a way chosen by the verifier, and to show the cryptographic hashvalue of this “altered secret”. The number of computations needed for this can bereduced if we allow encrypted communication between the prover and the verifier.The three role configurations together with the decision whether to use encryp-tion, gives a total of six protocols, all shown in the extended paper [1].2 Problem descriptionThe following is a more precise description of when this type of protocols is needed.Victor is a secret agent, and keeping secret his intelligence has a high priority.However, his mission is to protect Peggy from great dangers, so when needed,321protecting Peggy takes priority over keeping his information secret. Now he isconfronted with the following situation: Victor does not know whether certaininformation known to him, is also known to Peggy. (“Peggy is kindly invited fora dinner at Mallory’s place.”)1 Victor knows that Mallory is a very maliciousperson. If Peggy does know that she is kindly invited, Victor would like to sendher a warning message (“Don’t go there, it is a trap. You will get killed in case yougo there.”). However, if Peggy has somehow not received the invitation, Victorwould like to keep his warning for himself, as well as his knowledge of Peggy’sinvitation. Therefore, Victor asks Peggy to prove her knowledge of the invitation.Only after the proof, Victor will disclose his warning to Peggy.Peggy is willing to prove her knowledge of the invitation, but only if she canmake sure Victor does not cheat on her, and actually finds out about the invitationbecause he tricks her into telling him (she has been invited). That is, she onlywants to prove her knowledge of the invitation if Victor actually knew about theinvitation beforehand.The protocols described in the long version of this article facilitate the describedsituation. Both Victor and Peggy can initiate the protocol. Victor will not learnany property of the secret my means of the protocol. In the protocol, Peggy doesnot learn whether Victor actually knew about the invitation, other than from hispossible next actions, such as sending a warning.3 The ANITA projectThe research contributing to the protocols and this demonstation is the Adminis-trative and Normative Information-Transaction Agents project, ANITA for short.Its aim is to use multi-agent systems to provide methods for both complete andlegitimate information exchange of sensitive information, such as in the Dutchpolice domain. The Dutch police offers us a very interesting application area forour protocols. Police investigation teams typically want to keep their files secret,but do want to know whether other teams are investigating on the same personsor locations. If indeed multiple teams are investigating on the same person, theywould better co-operate, or at least make sure they do not hinder one another.References[1] W. Teepe. New protocols for proving knowledge of arbitrary secretswhile not giving them away. In Sieuwert van Otterloo, Peter McBur-ney, Wiebe van der Hoek, and Michael Wooldridge, editors, Proceedings ofthe Knowlegde and Games Workshop, Liverpool, July 2004. available athttp://www.ai.rug.nl/~woutr/provingsecrets/.[2] Wouter Teepe. The secret prover: Proving possession of arbitrary files whilenot giving them away. same volume.1For clarity, this information could be possession of a computer file stating the invitation.This sets apart the matter whether the information is truthful.322

New Protocols for Proving Knowledge of Arbitrary Secrets While not Giving Them Away

https://pure.rug.nl/ws/files/2915378/019proving.pdf

New Protocols for Proving Knowledge of Arbitrary Secrets While not Giving Them Away

Abstract

Similar works

Full text

Available Versions

ARTS repository - University of Groningen