Security amplification is an important problem in Cryptography: starting with a “weakly secure” variant of some cryptographic primitive, the goal is to build a “strongly secure” variant of the same primitive. This question has been successfully studied for a variety of important cryptographic primitives, such as one-way functions, collision-resistant hash functions, encryption schemes and weakl...

The complexity of voting procedures make it challenging to design a secure electronic voting system. In many proposals, the security of the system relies mainly on a black box voting machine. Meanwhile, the most advanced proposals base their security arguments on (complicated) cryptographic protocols, e.g. blind signatures or homomorphic schemes. Canard and Traoré proposed cryptographic primiti...

We introduce a formal quantitative notion of “bit security” for a general type of cryptographic games (capturing both decision and search problems), aimed at capturing the intuition that a cryptographic primitive with k-bit security is as hard to break as an ideal cryptographic function requiring a brute force attack on a k-bit key space. Our new definition matches the notion of bit security co...

Preface Another year, another thesis, another subject. Cryptography has always drawn my interest , though I have never known what it basically comes down to. Genetic algorithms on the other hand seemed a pretty nice idea to me, but I wanted to check its merits on a real problem. So this two reasons led me to choosing the subject of this thesis. I learned new things, and I discovered unexpected ...

In this paper we present two new n-quasigroup stream ciphers based on new n-quasigroup encryption scheme. Also, we present a practical implementation of these ciphers that has very good cryptographic properties. The implementation is based on a design concept of mixing two ”incompatible” group operations on the set Z28 .

Abstract We propose A ria NN, a low-interaction privacy-preserving framework for private neural network training and inference on sensitive data. Our semi-honest 2-party computation protocol (with trusted dealer) leverages function secret sharing, recent lightweight cryptographic that allows us to achieve an efficient online phase. design optimized primitives the building blocks of networks suc...

The ability to enforce robust and dynamic access controls on cloud-hosted data while simultaneously ensuring confidentiality with respect to the cloud itself is a clear goal for many users and organizations. To this end, there has been much cryptographic research proposing the use of (hierarchical) identity-based encryption, attribute-based encryption, predicate encryption, functional encryptio...

Abstract. Hummingbird is a novel ultra-lightweight cryptographic algorithm aiming at resource-constrained devices. In this work, an enhanced hardware implementation of the Hummingbird cryptographic algorithm for low-cost Spartan-3 FPGA family is described. The enhancement is due to the introduction of the coprocessor approach. Note that all Virtex and Spartan FPGAs consist of many embedded memo...