[HGI-News] HGI-Seminar am Mittwoch, 16.06.2004

[hgi-news at lists.ruhr-uni-bochum.de]

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			  Dr. Eike Kiltz
		Lehrstuhl Mathematik und Informatik 
			Ruhr-Universität Bochum 		 
            	  
        "Secure Constant Round Multi-Party Computation for 
		Equality, Comparison and Bits"



               Mittwoch, 16.06.2004, 13:30 hrs, 
		NA 1/58 (Friedrich-Sommer Raum)



Abstract

In this presentation we give efficient and secure constant round multi-party
protocols to compute shares of the bit indicating if a shared input value
$x \in \Z_q$ is zero or not providing a missing building stone for many
constant round linear algebra protocols from  a paper from Cramer and
Damgaard [CD01].  Furthermore, we present a secure and efficient constant
round protocol for computing shares of the binary representation of a shared
input value $x \in \Z_q$ improving on a result from [ACS02].
Our techniques can also be used to securely compute in constant rounds
shares of the bit indicating which of two shared inputs is bigger. The main
building stone of our protocols is a protocol to convert fromadditives
shares over $\Z_q$ to additive shares over the integers that works for all
shared inputs from $\Z_q$.  We also present a constant round protocol to
efficiently compute a secure approximation of the value $1/p$ for a given
shared $p$.  This enables us to do efficient computation modulo a shared
secret in a  constant number of rounds. Until now, for all the above
mentioned problems,  there were in general no constant round protocols
known. The main tools to obtain our protocols are the Chinese Remainder
Representation (CRR) and Lagrange Interpolation.





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VORTRÄGE IM SS 2004:
(Abstracts sind hier:
 www.crypto.ruhr-uni-bochum.de/Seminare/Krypt/Kryptosose04.htm)

 
 19.04.2004, Marc Stevens, ITSC - RUB, 13.00 c.t. IC 4/39,,
 "Arithmetic on Hyperelliptic curves of genus 1 and 2"

 26.04.2004, Jonathan Hammell, COSY - RUB, 13.00 c.t. IC 4/39,
 "Recognition in a Low-Power Environment"

 03.05.2004, Kai Schramm, COSY - RUB, 13.00 c.t. IC 4/39,
 "Internal Collisions in AES"

 17.05 Christian Tobias, JLU Gießen, 13.15 hrs. IC 4/39,
 "Design und Analyse kryptografischer Bausteine auf nicht-abelschen
Gruppen"

 24.05 Jamshid Shokrollahi, Uni Paderborn, 13.15 hrs. IC 4/39,
 "Unifying structures for polynomial and normal bases"

 31.05 no seminar (Holiday: Pfingsmontag)

 7.06 Lars Pontow, COSY Group -RUB, 13:15 hrs. IC 4/39,
 "Elliptic Curve Cryptography as a Case Study for Hardware/Software
Codesign"

 14.06 Kerstin Lemke, COSY Group -RUB, 13.15 hrs. IC 4/39,
 "DPA on n-bit sized Boolean and Arithmetic Operations and its   application
to IDEA, RC6 and the HMAC-Construction"

 16.06 Eike Kiltz, Lehrstuhl Mathematik und Informatik -RUB, 13:30 hrs. NA
1/58 (Friedrich-Sommer Raum)
"Secure Constant Round Multi-Party Computation for Equality, Comparison and
Bits"

 21.06 Howon Kim, COSY Group -RUB, 13.15 hrs. IC 4/39,
 "TBA"

 28.06 TBA

 5.07 Mark Manulis, NDS Group -RUB, 13:15 hrs. IC 4/39,
 "Pseudonym Generation Scheme for Ad-Hoc Group Communication based on  IDH"


 12.07 TBA

 19.07 TBA

 26.07 TBA



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M.Tech. Sandeep Kumar
Chair for Communication Security
Dept. of Electr. Eng. & Information Sciences
Ruhr-University Bochum
44780 Bochum, Germany

URL: www.crypto.rub.de