Injective one-way trapdoor functions are one of the most fundamental cryptographic primitives. In this work we show how to derandomize lossy encryption (with long messages) to obtain lossy trapdoor functions, and hence injective one-way trapdoor functions. Bellare, Halevi, Sahai and Vadhan (CRYPTO ’98) showed that if Enc is an IND-CPA secure cryptosystem, and H is a random oracle, then x 7→ Enc...

In this article we prove that quasi-multiplicative (with respect to the usual length function) mappings on the permutation group Sn (or, more generally, on arbitrary amenable Coxeter groups), determined by self-adjoint contractions fulfilling the braid or Yang-Baxter relations, are completely positive. We point out the connection of this result with the construction of a Fock representation of ...

We study representations of wreath product analogues of categories of finite sets. This includes the category of finite sets and injections (studied by Church, Ellenberg, and Farb) and the opposite of the category of finite sets and surjections (studied by the authors in previous work). We prove noetherian properties for the injective version when the group in question is polycyclic-by-finite a...

Throughout this lecture, we let k denote an algebraically closed field, ` a prime number which is invertible in k. In the previous, we define the `-adic cohomology H∗(X; Λ), where X is a quasi-projective k-scheme and Λ ∈ {Z`,Q`,Z/`Z}. Our first goal in this lecture is to review the corresponding theory of `-adic homology. Definition 1. Let Λ be a commutative ring, and let ModΛ denote the∞-categ...