Abstract Privacy and data confidentiality are today at the heart of many discussions. But such data protection should not be done at the detriment of other security aspects. In the context of network traffic, intrusion detection system becomes totally blind when the traffic is encrypted, making clients again vulnerable to known attacks. To reconcile security and privacy, BlindBox and BlindIDS are proposed to perform Deep Packet Inspection over an encrypted traffic, based on two different cryptographic techniques. But, on one side, even if BlindBox is quite efficient to detect an anomalous encrypted traffic, it necessitates a very high setup time for clients and servers and does not protect the know‐how of Security Editors (SEs) working on detection rules. On the other side, BlindIDS does protect SE's market and does not introduce any latency during setup time, but is definitely not enough efficient for a practical use. Herein, it is shown that the design of a fully efficient and market‐compliant intrusion detection system over an encrypted traffic is possible. The system is based on only symmetric cryptography, and permits to encrypt a packet of 1500 bytes in about 6 μs and to test such packets with 3000 rules in less than 2 μs.

With the development of wireless technology, the ubiquitous sensor networks have a profound effect on the way human interacts with computers, devices and environment. In order to reduce the potentially serious risks in the interaction, applying lightweight ciphers is effective to balance security, efficiency and convenience. Simeck is such a lightweight cipher that provides data confidentiality, authentication and integrity. It is significant to explore whether Simeck remains robust security. Up to now, the attacking assumptions of the previous security analysis of Simeck focus on the known-plaintext attack and the chosen-plaintext attack. There is no literature about Simeck against the ciphertext-only attack, which represents the weakest attacking capability of the attackers. On the assumption of the ciphertext-only attack, this paper proposes the security analysis of Simeck against the statistical fault analysis with a series of novel distinguishers of KDE, MME and MME-GF. The experimental results show that the proposed distinguishers can recover the secret key of Simeck in both decreasing faults and increasing reliability and accuracy. Thus, Simeck cannot resist against the statistical fault analysis with the proposed distinguishers. Furthermore, the good performance of these novel distinguishers can be applied on the PRESENT lightweight cipher. It offers the valuable reference for the design and analysis of the lightweight ciphers in the ubiquitous sensor networks.

At CRYPTO 2017 and IEEE Transactions on Computers in 2018, Todo et al. proposed the division property based cube attack method making it possible to launch cube attacks with cubes of dimensions far beyond practical reach. However, assumptions are made to validate their attacks. In this paper, we further formulate the algebraic properties of the superpoly in one framework to facilitate cube attacks in more successful applications: we propose the “flag” technique to enhance the precision of MILP models, which enable us to identify proper non-cube IV assignments; a degree evaluation algorithm is presented to upper bound the degree of the superpoly s.t. the superpoly can be recovered without constructing its whole truth table and overall complexity of the attack can be largely reduced; we provide a divide-and-conquer strategy to Trivium-like stream ciphers namely Trivium, Kreyvium, TriviA-SC1/2 so that the large scale MILP models can be split into several small solvable ones enabling us to analyze Trivium-like primitives with more than 1000 initialization rounds; finally, we provide a term enumeration algorithm for finding the monomials of the superpoly, so that the complexity of many attacks can be further reduced. We apply our techniques to attack the initialization of several ciphers namely 839-round Trivium, 891-round Kreyvium, 1009-round TriviA-SC1, 1004-round TriviA-SC2, 184-round Grain-128a and 750-round Acorn respectively.

With the enlargement of wireless technology, Internet of Things (IoT) is emerging as a promising approach to realize smart cities and address lots of serious problems such as safety, convenience and efficiency. In order to avoid any possible rancorous attacks, employing lightweight cryptosystems is most effective to implement encryption/decryption, message authentication and digital signature for security of the IoT. LED is such a lightweight cipher with two flexible keysize variants in the IoT. Since its designing, a multitude of fault analysis techniques in chosen plaintext attacks focus on provoking faults on LED to derive the 64-bit and 128-bit secret keys. It is vital to investigate whether injecting faults allows breaking LED while the attackers have the weakest ciphertext-only attacking ability. This study presents ciphertext-only fault analysis with six different distinguishers on LED. The simulating experiments show that our analysis can recover its 64-bit and 128-bit secret keys with over 99 percent probability using the SEI, GF, GF-SEI, ML, HW and MAP distinguishers. The attack can not only improve the attacking efficiency, but also decrease the number of faults. The fault locations can be injected into the deeper round. It provides vital reference for security analysis of other lightweight ciphers in the IoT.

In this paper, a family of new de Bruijn sequences is proposed through the construction of maximum-length nonlinear feedback shift registers (NFSRs). Let$k$be a positive integer and$p_{0}(x), p_{1}(x), \ldots , p_{k}(x)$be the primitive polynomials in$\mathbb {F}_{2}[x]$with their degrees strictly increasing and pairwise coprime. We determine the cycle structure and adjacency graphs of linear feedback shift registers (LFSRs) with characteristic polynomial$q(x)=\prod \nolimits _{i=0}^{k}p_{i}(x)$. In the case that$p_{0}(x)=1+x$, an algorithm is proposed to produce maximum-length NFSRs from these LFSRs, and it is shown that the algorithm can generate$O(2^{(2^{k}-1)n})~n$-stage maximum-length NFSRs with memory complexity$O(2^{k}kn)$and time complexity$O(2^{n-d_{k}}kn)$, where$n$and$d_{k}$are the degrees of$q(x)$and$p_{k}(x)$, respectively. Finally, we illustrate the proposed algorithm in the case of$k=2$. In this case, we prove that for any integer$n\geq 8$, the algorithm can produce$n$-stage maximum-length NFSRs with time complexity as low as$O(n^{{\rm {log}{log}}(n)}$).

In this paper, the cycle structure and adjacency graphs of a class of linear feedback shift registers (LFSRs) are determined. By recursively applying the D-morphism to the maximum-length LFSRs and representing the cycles by generating functions, a new family of maximum-length nonlinear feedback shift registers (NFSRs) are proposed based on the properties of these LFSRs. The number of NFSRs in the proposed family is also considered.

In this paper, a class of linear feedback shift registers (LFSRs) with characteristic polynomial (1 + x3)p(x) is discussed, where p(x) is a primitive polynomial of degree n > 2. The cycle structure and adjacency graphs of the LFSRs are determined. A new class of de Bruijn sequences is constructed from these LFSRs, and the number of de Bruijn sequences in the class is also considered. To illustrate the efficiency of constructing de Bruijn sequences from these LFSRs, an algorithm for producing some corresponding maximum-length nonlinear feedback shift registers with time and memory complexity O(n) is also proposed.