An Addendum to the ZUC-256 Stream Cipher

ZUC-256 is a stream cipher, together with AES-256 and SNOW-V, proposed as the core primitive in future set of 3GPP confidentiality and integrity algorithms for the upcoming 5G applications which offer the 256-bit security. \\ While the original initialization scheme of ZUC-256 can work with a 256-bit key and an IV of length up to 184 bits, we describe a new initialization scheme of ZUC-256 that supports an IV of the exact 128 bits in this paper. Compared to the original initialization scheme, this new key/IV setup algorithm avoids the division of the whole key/IV byte and provides a simple and natural-looking initialization scheme for ZUC-256

On the Linear Distinguishing Attack against ZUC-256 Stream Cipher

At FSE 2020, a linear distinguishing attack is presented against the ZUC-256 stream cipher based on the $32$-bit word with a data/time complexity of about $2^{236.38}$. In this paper, we re-evaluate the complexity of this attack and discuss the applicability of such a distinguishing attack in 5G application scenarios, where each keystream frame is limited to $20000$, and up to $2^{32}$ bits. To assure a high success probability close to $1$, it is shown that the precise time complexity of the distinguishing attack is $2^{253.93}$ basic operations with a data complexity of $2^{241.38}$ bits keystream, which is far beyond the keystream length limit in 5G application settings in the single-frame setting. Besides, we also consider the multiple-frame scenario where a long keystream could be formed by concatenating many short keystream frames generated from different (Key, IV) pairs. We show that even in such a strong model of distinguishing attacks, the reported bias will not exist in 5G application scenarios and the linear distinguishing attack will not work due to the fact that the long linear combination relation derived from the polynomial multiple of the LFSR in ZUC-256 over \mbox{GF}(2^{31}-1), which has been verified in experiments. It is concluded that the ZUC-256 stream cipher offers the full $256$-bit security in 5G application scenarios

Safety First Project

National audienceGuidelines (("Guidelines on alternative design and arrangements for fire safety", MSC/Circ.1002, June 2001)) forapplying Fire Risk Analysis ((FRA)) to alternative ship designs have been included in the international safety regulations.The aim of the SAFETY FIRST project is to develop and demonstrate a tried and tested "toolkit" for carrying out firerisk assessment for ships in accordance with Part F Regulation 17 of the new SOLAS Chapter II-2 and with theGuidelines.The Safety First project includes the collection and development of data and probabilistic models which could be usedfor assessing the fire risk associated with an alternative ship design. Probabilistic models have been developed for threecase studies, namely a passenger cabin fire, a fire in a three-deck atrium, and a fire/explosion in the parking deck of a roropassenger ferry.These models generally use data on real fires and on the reliability of fire protection measures, and include statistical,probabilistic models concerned with fire/smoke spread and damage. Quantifying uncertainties by probabilities, thesemodels provide a quantitative evaluation of fire risk and effectiveness of fire safety measures in probabilistic terms.Following a review of Fire Risk Assessment techniques, standard fire models, consisting of fault trees and event trees,have been developed for the case studies. They aim at describing the relevant factors that can have influence on firedevelopment and the spread of fire/smoke within and through ship space((s)).An estimate of the frequency of occurrence of fire outbreaks ((in terms of fire events per ship per year)) for "All Ships","Passenger Ships" and "Ro-Ro Ships" categories has been provided for several ships compartments by processing twoextracts of the Lloyds database, the first restricted to the EU Fleet and the second including the World Fleet. Theseestimates can be used to characterise the frequency of occurrence of the initiating events of event trees.Finally, failure statistics data for the main components of the on board fire protection systems, including fire detection((e.g. failure of smoke detectors or alarms)), fire containment ((e.g. failure of automatic closure of fire doors)) and fireextinction ((e.g. failure of sprinkler)) have been collected from other industrial sectors and from shipbuilders, equipmentmanufacturers and parts suppliers