The 1993 Stern authentication protocol is a code-based zeroknowledge protocol with cheating probability equal to 2/3 based on the syndrome decoding problem which permits to obtain a proof of knowledge of a small weight vector. This protocol was improved a few years later by Véron, who proposed a variation of the scheme based on the general syndrome decoding problem which leads to better results in term of communication. A few years later, the AGS protocol introduced a variation of the Véron protocol based on quasi-cyclic matrices. The AGS protocol permits to obtain an asymptotic cheating probability of 1/2 and a strong improvement in term of communications. In the present paper we propose two new contributions. First, a Quasi-Cyclic Stern proof of knowledge construction which constitutes an adaptation of the AGS scheme in a syndrome decoding context. The main interest of this adaptation is that at the difference of the regular (non quasi-cyclic) case, the Quasi-Cyclic Stern protocol is better in terms of communication than its Véron counterpart (the AGS protocol, which can be seen as a Quasi-Cyclic Véron protocol). The difference comes from the fact that a seed related optimization is better for QC-Stern than for QC-Véron. Secondly, we also propose a general new optimization to handle random seeds in this type of protocol. Overall, the two new optimizations we propose permit to gain about 17.5% in the length of communication compared to the previous best approach for this type of protocols. Such optimizations are of great matter in the ongoing context where a new signature call for proposals has been announced by the NIST and for which such zeroknowledge approaches are a real alternative, as it was shown in the first signature call for proposals of the NIST. At last, the paper also sums up the different known optimizations for such protocols and explain how our new approach can be adapted to other metrics.

This paper addresses the problem of planning with preferences using Multiple Criteria Decision Analysis (mcda) mechanisms. We start by explaining how pddl3 preferences can be modelled by criteria from the Multi-Attribute Utility Theory (maut) along with a Choquet integral. Interestingly, preferences formalized using maut have almost the same expressiveness as the ones formalized in pddl3 while being much easier to model. Next, we present a new heuristic for planning with preferences which is based on the Choquet integral. Finally, we introduce ChoPlan a proof-of-concept planner solving maut-encoded planning problems using the aforementioned heuristic. ChoPlan's performances are evaluated with respect to state of the art planners using problems from the fifth International Planning Competition.

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<p style='text-indent:20px;'>In this paper, we present a practicable chosen ciphertext timing attack retrieving the secret key of HQC. The attack exploits a correlation between the weight of the error to be decoded and the running time of the decoding algorithm of BCH codes. For the 128-bit security parameters of HQC, the attack runs in less than a minute on a desktop computer using roughly 6000 decoding requests and has a success probability of approximately 93 percent. To prevent this attack, we provide an implementation of a constant time algorithm for the decoding of BCH codes. Our implementation of the countermeasure achieves a constant time execution of the decoding process without a significant performance penalty.</p>