One of the most interesting research topics in cryptography is nding schemes for an e cient fully-homomorphic encryption (FHE), preferably information-theoretically secure schemes, which are not based on unproven computational hardness assumptions. The greatest breakthrough in this eld was made by Gentry [11] in 2009, and since then there were some interesting developments, e.g., Boneh et al. [...

Passwords and PINs continue to remain the most widespread forms of user authentication, despite growing awareness of their security limitations. This is because short secrets are convenient, particularly for an increasingly mobile user population. Many users are interested in employing a variety of computing devices with different forms of connectivity and different software platforms. Such use...

The notion of a semi-commutativity set for word mappings was defined in [3] as an abstraction of a problem in cryptography. The notion is of special interest in case the mappings are morphisms. Then rather surprising constructions become possible. We investigate such constructions, paying special attention to exceptional values of inverse mappings. Some of our results bear a close relation to c...

A prompting protocol permits users to securely retrieve secrets with greater entropy than passwords. The retrieved user secrets can have enough entropy to be used to derive cryptographic keys.

The gossip problem, in which information (known as secrets) must be shared among a certain number of agents using the minimum number of calls, is of interest in the conception of communication networks and protocols. We extend the gossip problem to arbitrary epistemic depths. For example, we may require not only that all agents know all secrets but also that all agents know that all agents know...

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...

Note: The last sentence on page 3 is not entirely accurate, in that only the number of multiplications decreases by a factor of j; the number of squarings is unaaected. Abstract. Consider a polynomial-time prover holding a set of secrets. We describe how the prover can rapidly demonstrate any satissable boolean formula for which the atomic propositions are relations that are linear in the secre...

be hypothesised that adaptation to pollinators has been a driving force behind the diversification of some of the major elements of the southern African flora, " Johnson writes. Southern African flowers are known to be attractive to a range of species from long-probscid flies, oil-bees, hawkmoths, butterflies, birds and rodents. Many of these pollination interactions have been characterised in ...