The scheme [IEEE Trans. Big Data, 4 (1), 2018, 26-39] is flawed because the sparsity of coefficient matrix is neglected. In the discussed scenario, we find it is unnecessary to outsource such a problem because the client can solve it locally. Even if the matrix is not sparse, the proposed paradigm which requires a great number of interactions, is rarely adopted because of the possibly incurred massive communication cost.

The scheme [1] is flawed because: (1) its circuit access structure is confusingly described; (2) the cloud server cannot complete the related computations; (3) some users can conspire to generate new decryption keys, without the help of the key generation authority.

Currently the industry moves to smaller process nodes even if the cost for yielding large dies continues to increase, moving to the 5nm and even 3nm nodes. Hence a chiplet-based design has been initiated and quickly gain attention from industry, academia and government agencies. This cutting edge approach became advantageous to break down a large die into smaller chiplets in order to improve yield and binning. In order to exploit this new approach the interconnect fabric connecting the nodes of the entire system should be of high importance to enable the properly distribution of the data. Each individual chiplet may contain its own local Network on Chip (NoC), which operates for intra-chiplet traffic. However the communication over chiplet-based systems is complicated enough, due to various routing algorithms and NoC topologies and an alternative solution is needed. In this paper we introduce an SDNoC(Software Define Network on Chip)-based communication protocol for chiplet-based systems, called MicroLET, which consists of a flexible and modular SDNoC architecture and 3 main phases: Handshake, Network Monitoring, Routing. An implementation of the SDNoC architecture and an evaluation of the proposed routing algorithm compared to the XY and the Odd-Even algorithms within different traffic scenarios is presented. Through the evaluation of the MicroLET protocol, it is proven that it could be a good candidate for the future chiplet-based systems.

In this work, we implement an identity-based Transport Layer Security (ID-TLS) protocol and integrate it on scalable multiprocessor system-on-chip (MPSoC), namely Cloud-of-Chips (CoC), in order to secure the SDN communication on this platform. We select two identity-based encryption schemes that are more likely to meet the performance and resource constraints on the target platform. The schemes are Sakai-Kasahara's identity-based encryption (SK-IBE) and the optimized identity-based encryption (OIBE) for lightweight devices by Guo et al. The results assert that both the schemes have their computation vs storage trade-off. The SK-IBE algorithm is significantly more computationally efficient than its OIBE counterpart while SK-IBE uses around 30 percent more memory than OIBE. However, the performance results of ID-TLS favor SK-IBE over OIBE. Finally, ID-TLS is integrated in the existing Open Flow switch and controller implementations. This brings us to a fully functional and secure ID-TLS implementation on CoC, keeping the platform constraints in consideration.

In recent years, Multi-Processor System-on-Chips (MPSoCs) are widely deployed in safety-critical embedded systems. The Cloud-of-Chips (CoC) is a scalable MPSoC architecture comprised of a large number of interconnected Integrated Circuits (IC) and Processing Clusters (PC) destined for critical systems. While many researches have focused on addressing the hardware issues of MPSoCs, the communication over them has not been very well explored. Following the SDN concept, we propose a new protocol in order to secure the communication and efficiently manage the routing within the CoC. The SSPSoC includes a private key derivation phase, a group key agreement (GKA) phase, and a data exchange phase in order to ensure that basic security primitives are preserved and provide secure communication. Furthermore, a network of 1-30 nodes is set in order to validate the proposed protocol and measure the network performance and memory consumption of the proposed protocol.

We show that Chen et al.'s schemes [IEEE TCC, 2(4), 2014, 499-508] for outsourcing linear regression computation to the cloud are not unquestioned. In scheme 1, the client has to generate an orthogonal matrix. Its computational complexity is almost equal to that of solving a linear regression problem locally. In such case, the client has no necessary to outsource the computations to the cloud. In scheme 2, it masks a matrix by multiplying two diagonal matrixes. The linear transformation is very vulnerable to statistical attack.

Side-channel adversaries represent real-world threats against (certified and uncertified) cryptographic devices. Masking schemes represent prevailing countermeasures to reduce the success probabilities of side-channel attacks. However, masking schemes increase the implementation cost in terms of power consumption, clock cycles, and random number generation. Investigation of tools evaluating the degree of resilience of cryptographic devices using masking (against side-channel attacks) represents an important aspect in certification procedures (e.g., common criteria, FIPS 140-2, and EMVco). Several side-channel evaluation techniques exist such as template attacks and machine learning-based attacks. In this paper, we formalize results obtained in side-channel attacks community when targeting masked implementations. We report theoretical as well as practical results of parametric and non-parametric side-channel attacks on masking schemes. The theoretical part reports results based on a simulation of the execution of software devices, while the practical part focuses on actual leakages measured during the execution of a software implementation in three different contexts (that contain different levels of noise).

Masking schemes represent a well-researched and successful option to follow when considering side-channel countermeasures. Still, such measures increase the implementation cost in terms of power consumption, clock cycles, and random numbers generation. In fact, the higher the order of protection against side-channel adversaries, the higher the implementation cost of countermeasures. S-boxes represent the most vulnerable part in an implementation when considering side-channel adversary. In this paper, we investigate how to generate S-boxes that have improved resilience against varying orders of side-channel attacks while having minimal implementation costs. We examine whether S-boxes generated against a certain order of attack also represent a good solution when considering different order of attacks. We demonstrate that we successfully generated S-boxes resilient against a certain physical attack order but the improvements are small. As a result, S-boxes that are resilient against first order attacks stay resilient against higher-order attacks, which saves computational power during the design of higher-order side-channel attacks resilient S-boxes.

A symmetric group key agreement protocol enables the group members to derive a shared session key for secure communication among them, while an asymmetric one facilitates security to any communication from outside, without adding outsiders into the group. In this paper, we propose a twofold group key agreement protocol which addresses the need of a shared symmetric key among insider members in a group and an asymmetric key pair for any unrestricted sender. In particular, we look forward for a solution to provide secure communication among multiple processing clusters (PCs) actively running on an integrated circuit (IC). The proposed protocol offers a lightweight symmetric encryption for intra zone communication and a public key encryption for inter zone communication taking most advanced security issues into account.

Evaluating the resistance of cryptosystems to side-channel attacks is an important research challenge. Profiled attacks reveal the degree of resilience of a cryptographic device when an adversary examines its physical characteristics. So far, evaluation laboratories launch several physical attacks (based on engineering intuitions) in order to find one strategy that eventually extracts secret information (such as a secret cryptographic key). The certification step represents a complex task because in practice the evaluators have tight memory and time constraints. In this paper, we propose a principled way of guiding the design of the most successful evaluation strategies thanks to the (bias-variance) decomposition of a security metric of profiled attacks. Our results show that we can successfully apply our framework on unprotected and protected algorithms implemented in software and hardware.

Side‐channel attacks provide tools to analyse the degree of resilience of a cryptographic device against adversaries measuring leakages (e.g. power traces) on the target device executing cryptographic algorithms. In 2002, Chari et al . introduced template attacks (TA) as the strongest parametric profiled attacks in an information theoretic sense. Few years later, Schindler et al . proposed stochastic attacks (representing other parametric profiled attacks) as improved attacks (with respect to TA) when the adversary has information on the data‐dependent part of the leakage. Less than ten years later, the machine learning field provided non‐parametric profiled attacks especially useful in high dimensionality contexts. In this study, the authors provide new contexts in which profiled attacks based on machine learning outperform conventional parametric profiled attacks: when the set of leakages contains errors or distortions. More precisely, the authors found that (i) profiled attacks based on machine learning remain effective in a wide range of scenarios, and (ii) TA are more sensitive to distortions and errors in the profiling and attacking sets.

The issue of event-ordering in distributed systems is crucial an connected to threat management. In this paper, we investigate the use of modifications for handling event-ordering. We employ category theory to strike a balance between Lamport clocks, which enforce global order but lose information about causality, and Vector clocks, which have more precise causality information but do not scale well. We extend previous work on Godement calculus and cartesian closed comma categories for information security management. Finally, we propose a framework for implementing our approach in the detection of threats and attacks in communication systems.

Mobile security is of paramount importance. The security of LTE (long term evolution of radio networks), which is currently widely deployed as a long-term standard for mobile networks, relies upon three cryptographic primitives, among which the stream cipher ZUC. In this paper, we point out that the linear feedback shift register (LFSR) used in ZUC has about 225 encodings of the zero state (i.e. all LFSR variables are 0) due to the fact that operations are performed modulo 231 -- 1 on 32-bit operands. We use SAT solvers to show that these states are reachable when 64 bits of ZUC's initial state can be chosen (i.e. R1, R2). That is, for each key there are many initial vectors that lead to a weak state after ZUC's initialization. We also use SAT-solvers to disprove the existence of such weak inputs when the initial values of R1, R2 are set to zero as required by the official specifications. Finally, we discuss how the redundancy introduced in ZUC's output function might help mounting SAT-solver based guess-and-determine attacks given a few keystream digits.

Authenticated key agreement protocols provide wireless technologies with fundamental mechanisms such as session key generation and device authentication. Many of these protocols have been designed specifically for those technologies, but most of them do not integrate all the security requirements, and others have been attacked. Another important issue that arises in practice is related to key management, since the deployement and replacement of keying material is costly and may potentially lead to security vulnerabilities. For these reasons, we propose a generic authenticated key agreement protocol in which the long term secret is automatically and periodically renewed. The focus of this work is to formally assess the security offered by the protocol's key renewing in the case of a long term use of the system. The formal analysis is carried using the automated tools ProVerif and AVISPA. The protocol is designed to rely only on symmetric key algorithms and is suitable for devices that have limited hardware capabilities.