We consider the problem of answering queries against a knowledge base (KB) using secrets, whenever it is possible to do so without compromising secrets. We study query answering against EL knowledge bases. We provide a polynomial time algorithm that, given an EL KB Σ, a set S of secrets to be protected and a query q or the form C(a) or r(a, b), outputs “Yes” whenever Σ q and the answer to q, to...

Alice has n secrets which she regards as equally valuable. She is willing to sell any of them to Bob, but wants to ensure that if he pays for only one secret he cannot obtain any information about the others. Bob would like to buy one of the secrets from Alice, but wants to ensure that Alice can obtain no information about which of her secrets he has obtained. The aim of an all-or-nothing discl...

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This paper describes biometric-based cryptographic techniques that use weak secrets to provide strong, multi-factor and mutual authentication, and establish secure channels for subsequent communications. These techniques rely on lightweight cryptographic algorithms for confidential information exchange. Lightweight algorithms are suitable for use in resource constrained environments such as the...