Rate-limited secure function evaluation

Özgür Dagdelen, Payman Mohassel, Daniele Venturi

Özgür Dagdelen, Payman Mohassel, Daniele Venturi

Abstract. We introduce the notion of rate-limited secure function evaluation (RL-SFE). Loosely speaking, in an RL-SFE protocol participants can monitor and limit the number of distinct inputs (i.e., rate) used by their counterparts in multiple executions of an SFE, in a private and verifiable manner. The need for RL-SFE naturally arises in a variety of scenarios: e.g., it enables service providers to “meter ” their customers ’ usage without compromising their privacy, or can be used to prevent oracle attacks against SFE constructions. We consider three variants of RL-SFE providing different levels of security. As a stepping stone, we also formalize the notion of commit-first SFE (cf-SFE) wherein parties are committed to their inputs before each SFE execution. We provide compilers for transforming any cf-SFE protocol into each of the three RL-SFE variants. Our compilers are accompanied with simulation-based proofs of security in the standard model and show a clear tradeoff between the level of security offered and the overhead required. Moreover, motivated by the fact that in many client-server applications clients do not keep state, we also describe a general approach for transforming the resulting RL-SFE protocols into stateless ones. As a case study, we take a closer look at the oblivious polynomial evaluation (OPE) protocol of

Donald Beaver

Thomas H. Schneider

Oluwatobi Olabiyi, Alagappan Annamalai

Two unified analytical frameworks that facilitate the evaluation of the ergodic secrecy rates of Wyner wiretap channel in generalized fading environments without/with diversity receivers are developed. In contrast to prior work that is limited to only the Rayleigh fading environment, our new formulas expressed in terms of only the moment generating function (MGF) or the cumulative distribution function (CDF) of fading signal-to-noise ratio (SNR) random variables allow us to investigate the role of fading (i.e., Effects of the amount of fading and non-identical fade distributions) between the main and the eavesdropper links as well as the impact of diversity receivers on the ergodic secrecy rate performance metric. Numerical results show that non-zero ergodic secrecy rate can be achieved even if the link quality of the main channel is worse than the eavesdropper's channel. We also show that the fundamental limit of secure communication rate can be greatly improved by understanding the role of dissimilar fading statistics and by exploiting/mitigating channel effects via diversity reception.

Mohammad Mahmoody, Hemanta K. Maji, Manoj Prabhakaran

The seminal result of Impagliazzo and Rudich (STOC 1989) gave a black-box separation between one-way functions and public-key encryption: informally, a public-key encryption scheme cannot be constructed using one-way functions as the sole source of computational hardness. In addition, this implied a black-box separation between one-way functions and protocols for certain Secure Function Evaluation (SFE) functionalities (in particular, Oblivious Transfer). Surprisingly, however, {\em since then there has been no further progress in separating one-way functions and SFE functionalities} (though several other black-box separation results were shown). In this work, we present the complete picture for deterministic 2-party SFE functionalities. We show that one-way functions are black-box separated from {\em all such SFE functionalities}, except the ones which have unconditionally secure protocols (and hence do not rely on any computational hardness), when secure computation against semi-honest adversaries is considered. In the case of security against active adversaries, a black-box one-way function is indeed useful for SFE, but we show that it is useful only as much as access to an ideal commitment functionality is useful. Technically, our main result establishes the limitations of random oracles for secure computation.