This paper presents three methods for strengthening public key cryptosys tems in such a way that they become secure against adaptively chosen ciphertext attacks In an adaptively chosen ciphertext attack an attacker can query the deciphering algorithm with any ciphertexts except for the exact object cipher text to be cryptanalyzed The rst strengthening method is based on the use of one way hash ...

This paper presents three methods for strengthening public key cryptosystems in such a way that they become secure against adaptively chosen ciphertext attacks. In an adaptively chosen ciphertext attack, an attacker can query the deciphering algorithm with any cipher-texts, except for the exact object ciphertext to be cryptanalyzed. The rst strengthening method is based on the use of one-way ha...

We present efficient compression algorithms for subgroups of multiplicative groups of finite fields, we use our compression algorithms to construct efficient public key cryptosystems called T2 and CEILIDH, we disprove some conjectures, and we use the theory of algebraic tori to give a better understanding of our cryptosystems, the Lucas-based, XTR and Gong-Harn cryptosystems, and conjectured ge...

We propose public-key cryptosystems with public key a system of polynomial equations, algebraic or differential, and private key a single polynomial or a small-size ideal. We set up probabilistic encryption, signature, and signcryption protocols.

We propose public-key cryptosystems with public key a system of polynomial equations, algebraic or differential, and private key a single polynomial or a small-size ideal. We set up probabilistic encryption, signature, and signcryption protocols.

Finding efficient countermeasures for cryptosystems against fault attacks is challenged by a constant discovery of flaws in designs. Even elements, such as public keys, that do not seem critical must be protected. From the attacks against RSA [5,4], we develop a new attack of DLP-based cryptosystems, built in addition on a lattice analysis [26] to recover DSA public keys from partially known no...

Distributed key generation cryptosystems has a major content called distributed key generation (DKG) protocol. This protocol allows number of participants of group to generate a set of keys such as private key and public key without determining some trusted participants. Only authorized subgroups of participants are capable to regenerate or implement the private key and the public key is an out...

General fault attacks on multivariate public key cryptosystems

We investigate the discrete logarithm problem over jacobians of hyperelliptic curves suitable for public-key cryptosystems. We focus on the case when the definition field has small characteristic 2, 3, 5 and 7, then we present hyperelliptic cryptosystems that resist against all known attacks. We further implement our designed hyperelliptic cryptosystems over finite fields F2n in software on Alp...