This study presents a dynamic cube attack on the algorithm Grain-v1 which has resisted all the key-recovery attacks in the single key model. The dynamic cube attack finds the secret key by using distinguishers obtained from structural weaknesses of a cipher. The main idea of the attack lies in simplifying the cipher's output function. After making it simpler, the attack is able to exploit a distinguishing attack to recover the secret key. In this study, the authors first find the appropriate simplifications for Grain-v1. Then, they apply their attack to the algorithm by using a new framework and a new smart choice technique for the classification of initial value bits. Finally, the authors simulate the attack to find the suitable attack parameters having 73% success rate. Their attack runs in a practical time and recovers all the key bits when the number of initialisation rounds in Grain-v1 is reduced to 100 of 160. The attack is faster than exhaustive search by a factor of 2³⁸.

Hazay et al. initiated the formal study of leakage-resilient message authentication code (MAC) and presented a MAC scheme that is both leakage resilient and unforgeable against chosen message and no verification query attack (uf-cm-nvq). As the communication overhead of their construction is linear with the parameters that control the leakage bound, their scheme sacrifices efficiency in exchange for leakage resilience. In this study, the authors study the problem of designing leakage-resilient MACs in the public-key setting with acceptable communication efficiency. In particular, a notion called ‘hidden identity weak hash proof system’(HID-wHPS) is introduced. Then a generic MAC construction is presented under the abstraction framework of HID-wHPS. Security properties guaranteed by HID-wHPS enable us to prove the author's construction to be both leakage resilient and uf-cm-nvq in a modular way. Finally, performance analysis shows that their MAC construction yields improved tagging-key size, tag size as well as computation overhead under the given leakage bound.

Mobile ad hoc networks (MANETs) are wireless networks that have a wide range of applications because of their dynamic topologies and ease of deployment. Owing to the independent and dynamic nature of mobile nodes, the topology of a MANET often changes and is prone to various attacks. Therefore, substantial research in the area of security is required. Certificate revocation is an effective mechanism for providing network security services. However, the existing schemes are not well suited to MANETs because of their considerable overhead or low accuracy with respect to certificate revocation. In this study, the authors investigate a distributed certificate revocation protocol. On the basis of the game-theoretic model, they design a new voting-based security scheme. Their game-based security paradigm can provide the ability to practically respond to the current system conditions and is suitable for real MANET operations. Simulation results demonstrate the effectiveness and the efficiency of their scheme with respect to certificate revocation. Finally, they discuss the results of an evaluation provide an outlook on the future work in this field.

Public-key distance bounding protocols are well suited to defeat relay attacks in proximity access control systems when the author assume no prior shared key. At AsiaCCS 2014, Gambs, Onete, and Robert designed such a protocol with privacy protection for the prover. That is, the protocol hides the identity of the prover to active adversaries and the prover remains anonymous. In this study the author contradicts the result on this protocol by proving that an active adversary can easily identify one prover out of two possible ones. At WISEC 2013, Hermans, Peeters, and Onete proposed another protocol which is proven to protect the privacy of the prover. In this study the author complete their results and show that the protocol does not protect it in a strong sense. That is, if the adversary can corrupt the provers, then privacy is not guaranteed any more.

One of the approaches to modify the McEliece cryptosystem to overcome its large key size is replacing binary Goppa codes with a new structured code. However, this modification makes such cryptosystems encounter some new attacks. There are a few modified McEliece cryptosystem variants which are known to be secure. One of them is the cryptosystem introduced by Baldi et al. which uses quasi-cyclic low-density parity check (QC-LDPC) codes. This cryptosystem is still unbroken as no efficient attack has been reported against it since 2008. In this study, an attack has been applied to this cryptosystem which is feasible when the code length is a multiple of a power of 2. Also an important weakness of this kind of cryptosystem has been pointed out, namely utilising a too low-weight intentional error vector. The authors have established a new security level for this cryptosystem which is applicable to other McEliece-like cryptosystems using QC-LDPC codes. This security level for instance is 2^9.18 times lower than previous ones in the case of n = 4 × 4096 when only one ciphertext is available. The gain of the attack in this study can be increased if more than one ciphertext is available.

Security concerns are still retarding cloud adoption. While the research community work on clearing these concerns, an optimistic fair cloud compliant logging scheme may ease the cloud to spread. This study proposes a secure logging mechanism. The mechanism employs an online bulletin board as a public write-only storage for the log records. The bulletin board also acts as a trusted third party during conflict resolution. The secure logging protocol describes how the log records are distributed to the stakeholders. The protocol's security is verified with model checking tools and no security threats could be found.

The block cipher KASUMI, proposed by ETSI SAGE over 10 years ago, is widely used for security in many synchronous wireless standards nowadays. For instance, the confidentiality and integrity of 3G mobile communications systems depend on the security of KASUMI. Up to now, there is a great deal of cryptanalytic results on KASUMI. However, its security evaluation against the recent zero-correlation linear attacks is still lacking. In this study, combining with some observations on the FL, FO and FI functions, the authors select some special input/output masks to refine the general 5-round zero-correlation linear approximations and propose the 6-round zero-correlation linear attack on KASUMI. Moreover, under the weak key conditions that the second keys of the FL function in rounds 2 and 8 have the same values at 1st–8th and 11th–16th bit-positions, they expand the attack to 7-round KASUMI (2–8). These weak keys take 1/2¹⁴ of the key space. The new zero-correlation linear attack on the 6-round needs about 2¹¹⁸ encryptions with 2^62.9 known plaintexts and 2⁵⁴ bytes memory. For the attack under weak keys conditions on the last 7 rounds, the data complexity is about 2^62.1 known plaintexts, and the time complexity is about 2^110.5 encryptions, and the memory requirement is about 2⁸⁵ bytes.