Showing papers on "Secure multi-party computation published in 1990"

Generalized secret sharing and monotone functions

Abstract: Secret Sharing from the perspective of threshold schemes has been well-studied over the past decade. Threshold schemes, however, can only handle a small fraction of the secret sharing functions which we may wish to form. For example, if it is desirable to divide a secret among four participants A, B, C, and D in such a way that either A together with B can reconstruct the secret or C together with D can reconstruct the secret, then threshold schemes (even with weighting) are provably insufficient.This paper will present general methods for constructing secret sharing schemes for any given secret sharing function. There is a natural correspondence between the set of "generalized" secret sharing functions and the set of monotone functions, and tools developed for simplifying the latter set can be applied equally well to the former set.

Some ideal secret sharing schemes

Abstract: In a secret sharing scheme, a dealer has a secret. The dealer gives each participant in the scheme a share of the secret. There is a set Γ of subsets of the participants with the property that any subset of participants that is in Γ can determine the secret. In a perfect secret sharing scheme, any subset of participants that is not in Γ cannot obtain any information about the secret. We will say that a perfect secret sharing scheme is ideal if all of the shares are from the same domain as the secret. Shamir and Blakley constructed ideal threshold schemes, and Benaloh has constructed other ideal secret sharing schemes. In this paper, we construct ideal secret sharing schemes for more general access structures which include the multilevel and compartmented access structures proposed by Simmons.

A realization scheme for the identity-based cryptosystem

Abstract: At Crypto ′84, A. Shamir [1] presented the new concept of identity-based cryptosystems. Yet no realization scheme has yet been proposed. This paper proposes a scheme for realizing an identity-based cryptosystem which modifies Shamir's original concept without losing its essential characteristics. The fundamental idea of this realization scheme is based on the well-known one-way functions, “the difficulty of calculating a discrete logarithm” and “the difficulty of factoring the composite of two large primes.” As long as all the users in the system keep their own secret keys secure, this cryptosystem is perfectly secure. Even if there is a conspiracy among users in the system, this system remains secure when the number of conspirators is less than a certain number which has been determined during the design phase. In this way, a threshold scheme for a secret information sharing system is realized. This paper presents a detailed analysis of this threshold scheme and shows how to evaluate the secret key of the center when the number of conspiring users is over the threshold. In addition, a scheme which facilitates a reduction in the amount of computation needed to generate a common key is also presented.

Information sharing in secure systems

Abstract: The author attempts to establish a theoretical foundation for secure information sharing. He proposes a secure system structuring construct, called a secure object manager, as an example of a one-way information sharing mechanism. Secrecy, integrity, and availability requirements for the secure object manager are defined. A formal system model, including a careful treatment of communication via bounded buffers, is developed. Then he formally defines secrecy in terms of the model. This definition of secrecy precludes all covert channels, including storage, probabilistic, and timing channels. An implementation of the secure object manager that satisfies all the requirements considered is presented. >