Abstract of /TIGKI/INFOSYS/FKI/FKI-245-02

Document-Name:  fki-245-02.ps.gz
Title:		Secure and Private Auctions without Auctioneers
Authors:	Felix Brandt 
Revision-Date:	Februar 2002
Category:	Technical Report (Forschungsberichte Künstliche Intelligenz)
Abstract:	Security and privacy have become crucial factors in auction
		design. Various schemes to ensure the safe conduction of
		sealed-bid auctions have been proposed recently. We introduce
		a new standard of security for auctions (``full privacy''),
		that prevents extraction of bid information despite any 
		collusion of participants. This requirement is stronger than 
		other common assumptions that prohibit the collusion of
		certain third-parties (e.g., distinct auctioneers). Full 
		privacy is obtained by distributing shares of each bid on
		all bidders. The bidders then jointly compute the selling 
		price without uncovering any additional information.
		Auctioneers are obsolete in these  ``bidder-resolved'' 
		auction protocols. The auction outcome cannot be changed by 
		dishonest bidders; they can only inhibit the protocol. For 
		this reason, we present a sub-protocol that detects
		dishonest bidders, so that they can be fined, which
		provides the incentive to follow the main protocol.
		The major contribution of this work is the fully private 
		Vickrey auction protocol that determines the second-highest
		bid without revealing any other information. As full
		privacy is our main goal, the drawback of our protocol
		is efficiency. For this reason, it is currently only
		applicable for high-security auctions with relatively
		few bidders in reasonable time.
Keywords:	agents, auctions, cryptography
Size:		15 pages
Language:	English
ISSN:		0941-6358
Copyright:      The ``Forschungsberichte Künstliche Intelligenz''
                series includes primarily preliminary publications,
                specialized partial results, and supplementary
                material. In the interest of a subsequent final
                publication these reports should not be copied. All
                rights and the responsibility for the contents of the
                report are with the authors, who would appreciate
                critical comments.

Matthias Nickles