International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Rune Thorbek

Publications

Year
Venue
Title
2008
EPRINT
Efficient Conversion of Secret-shared Values Between Different Fields
Ivan Damgård Rune Thorbek
We show how to effectively convert a secret-shared bit $b$ over a prime field to another field. If initially given a random replicated secret share this conversion can be done by the cost of revealing one secret shared value. By using a pseudo-random function it is possible to convert arbitrary many bit values from one initial random replicated share. Furthermore, we generalize the conversion to handle general values of a bounded size.
2007
EUROCRYPT
2007
EPRINT
Non-Interactive Proofs for Integer Multiplication
Ivan Damgård Rune Thorbek
We present two universally composable and practical protocols by which a dealer can, verifiably and non-interactively, secret-share an integer among a set of players. Moreover, at small extra cost and using a distributed verifier proof, it can be shown in zero-knowledge that three shared integers $a,b,c$ satisfy $ab =c$. This implies by known reductions non-interactive zero-knowledge proofs that a shared integer is in a given interval, or that one secret integer is larger than another. Such primitives are useful, e.g., for supplying inputs to a multiparty computation protocol, such as an auction or an election. The protocols use various set-up assumptions, but do not require the random oracle model.
2006
PKC
2006
EPRINT
Linear Integer Secret Sharing and Distributed Exponentiation
Ivan Damgård Rune Thorbek
We introduce the notion of Linear Integer Secret-Sharing (LISS) schemes, and show constructions of such schemes for any access structure. We show that any LISS scheme can be used to build a secure distributed protocol for exponentiation in any group. This implies, for instance, distributed RSA protocols for arbitrary access structures and with arbitrary public exponents.

Coauthors

Ivan Damgård (5)