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CSFW
2006
IEEE

Resolve-Impossibility for a Contract-Signing Protocol

14 years 5 months ago
Resolve-Impossibility for a Contract-Signing Protocol
Abstract. A multi-party contract signing protocol allows a set of participants to exchange messages with each other with a view to arriving in a state in which each of them has a pre-agreed contract text signed by all the others. Such a protocol was introduced by Garay and MacKenzie in 1999; it consists of a main protocol and a sub-protocol involving a trusted party. Their protocol was shown to have a flaw by Chadha, Kremer and Scedrov in CSFW 2004. Those authors also presented a fix – a revised sub-protocol for the trusted party. In our work, we show an attack on the revised protocol for any number n > 4 of signers. Furthermore, we generalise our attack to show that the message exchange structure of Garay and MacKenzie’s main protocol is flawed: whatever the trusted party does will result in unfairness for some signer. This means that it is impossible to define a trusted party protocol for Garay and MacKenzie’s main protocol; we call this “resolveimpossibility”.
Aybek Mukhamedov, Mark Dermot Ryan
Added 10 Jun 2010
Updated 10 Jun 2010
Type Conference
Year 2006
Where CSFW
Authors Aybek Mukhamedov, Mark Dermot Ryan
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