Berry Schoenmakers

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In this paper we present a new multi-authority secret-ballot election scheme that guarantees privacy, universal verifiability, and robustness. It is the first scheme for which the performance is optimal in the sense that time and communication complexity is minimal both for the individual voters and the authorities. An interesting property of the scheme is(More)
Suppose we are given a proof of knowledge P in which a prover demonstrates that he knows a solution to a given problem instance. Suppose also that we have a secret sharing scheme S on n participants. Then under certain assumptions on P and S, we show how to transform P into a witness indistinguishable protocol, in which the prover demonstrates knowledge of(More)
A publicly verifiable secret sharing (PVSS) scheme is a verifiable secret sharing scheme with the property that the validity of the shares distributed by the dealer can be verified by any party; hence verification is not limited to the respective participants receiving the shares. We present a new construction for PVSS schemes, which compared to previous(More)
In this paper we present a new multi-authority secret-ballot election scheme that guarantees privacy, universal veriiability, and ro-bustness. It is the rst scheme for which the performance is optimal in the sense that time and communication complexity is minimal both for the individual voters and the authorities. An interesting property of the scheme is(More)
We present new cryptographic protocols for multi-authority secret ballot elections that guarantee privacy, robustness, and universal verifiability. Application of some novel techniques, in particular the construction of witness hiding/indistinguishable protocols from Cramer, Damg̊ard and Schoenmakers, and the verifiable secret sharing scheme of Pedersen,(More)
We present new results in the framework of secure multiparty computation based on homomorphic threshold cryptosystems. We introduce the conditional gate as a special type of multiplication gate that can be realized in a surprisingly simple and efficient way using just standard homomorphic threshold ElGamal encryption. As addition gates are essentially for(More)
We present a solution to the Tiercé problem, in which two players want to know whether they have backed the same combination (but neither player wants to disclose its combination to the other one). The problem is also known as the socialist millionaires’ problem, in which two millionaires want to know whether they happen to be equally rich. In our solution,(More)
Yao’s classical millionaires’ problem is about securely determining whether x > y, given two input values x, y, which are held as private inputs by two parties, respectively. The output x > y becomes known to both parties. In this paper, we consider a variant of Yao’s problem in which the inputs x, y as well as the output bit x > y are encrypted. Referring(More)
A family of pseudorandom generators based on the decisional DiffieHellman assumption is proposed. The new construction is a modified and generalized version of the Dual Elliptic Curve generator proposed by Barker and Kelsey. Although the original Dual Elliptic Curve generator is shown to be insecure, the modified version is provably secure and very(More)