This paper derives some further results on unconditionally secure asym-metric authentication schemes. It starts by giving a general framework for constructing A 2-codes, identifying many known constructions as special cases. Then a full treatment of A 3-codes (A 2-codes protecting against arbiter's attacks) is given, including bounds on the parameters and optimal constructions. With these model...

Secure keyword search in shared infrastructures prevents stored documents from leaking sensitive information to unauthorized users. A shared index provides confidentiality if it is exclusively used by users authorized to search all the indexed documents. We introduce the Lethe indexing workflow to improve query and update efficiency in secure keyword search. The Lethe workflow clusters together...

in mobile ad hoc networks, the absence ofinfrastructure and the consequent absence of authorizationfacilities impede the usual practice of establishing a practicalcriterion to distinguishing nodes as trusted and distrusted.since all nodes in the manets would be used as router inmulti-hop applications, secure routing protocols have vital rulein the security of the network. so evaluating the perf...

This paper describes efficient protocols for multi-party computations that are information-theoretically secure against passive attacks. The results presented here apply to access structures based on quorum systems, which are collections of sets enjoying a naturallymotivated self-intersection property. Quorum-based access structures include threshold systems but are far richer and more general,...

Ensuring the preservation of security is a key requirement and challenge for Service-Based Systems (SBS) due to the use of third party software services not operating under different security perimeters. In this paper, we present an approach for verifying the security properties of SBS workflows and adapting them if such properties are not preserved. Our approach uses secure service composition...

Security is an important issue in health care environments where large amounts of highly sensitive personal data are processed. It is therefore important that both the technical considerations and the security requirements (availability, integrity and confidentiality) are taken into account as main design objectives when designing a distributed medical database system. The aim of this paper has...

Home ad-hoc networks are sets of devices that interact to offer enhanced services to the users. These networks are heterogeneous, dynamic and fully decentralized. Moreover, they generally lack of a skilled administrator. These properties dramatically reduce the efficiency of classical security approaches: even defining the boundaries of such networks can be difficult. Ways to solve this problem...

We present Knock Yourself Out (KYO), a password generator that enables secure authentication against a computationally unbounded adversary. Master passwords can be surprisingly short and may be re-used for multiple service accounts even in the event of client compromises and multiple server compromises. At the same time, KYO is transparent to service operators and backwards-compatible. Master p...

Let ďc be computable reducibility on ceers. We show that for every computably enumerable equivalence relation (or ceer) R with infinitely many equivalence classes, the index sets ti : Ri ďc Ru (with R non-universal), ti : Ri ěc Ru, and ti : Ri ”c Ru are Σ3 complete, whereas in case R has only finitely many equivalence classes, we have that ti : Ri ďc Ru is Π2 complete, and ti : Ri ěc Ru (with R...

Kim and Bishu (Fuzzy Sets and Systems 100 (1998) 343-352) proposed a modification of fuzzy linear regression analysis. Their modification is based on a criterion of minimizing the difference of the fuzzy membership values between the observed and estimated fuzzy numbers. We show that their method often does not find acceptable fuzzy linear regression coefficients and to overcome this shortcomin...