Entanglement swapping of maximally entangled states

We consider entanglement swapping schemes for maximally entangled states, each of which is realized by Bell measurements. The entangled states considered include bipartite maximally entangled states, d-level Bell states and Greenberger-Horne-Zeilinger states. We also consider the entanglement swapping chains proposed by Hardy et al. [Phys. Rev. A. 62(5) 052315] for maximally entangled states. Applications of the proposed entanglement swapping schemes in quantum cryptography are described

Toward an RSU-unavailable lightweight certificateless key agreement scheme for VANETs

Vehicle ad-hoc networks have developed rapidly these years, whose security and privacy issues are always concerned widely. In spite of a remarkable research on their security solutions, but in which there still lacks considerations on how to secure vehicle-to-vehicle communications, particularly when infrastructure is unavailable. In this paper, we propose a lightweight certificateless and one-round key agreement scheme without pairing, and further prove the security of the proposed scheme in the random oracle model. The proposed scheme is expected to not only resist known attacks with less computation cost, but also as an efficient way to relieve the workload of vehicle-to-vehicle authentication, especially in no available infrastructure circumstance. A comprehensive evaluation, including security analysis, efficiency analysis and simulation evaluation, is presented to confirm the security and feasibility of the proposed scheme

Decoherence Effects in a Three-Level System under Gaussian Process

When subjected to a classical fluctuating field characterized by a Gaussian process, we examine the {purity} and coherence protection in a three-level quantum system. This symmetry of the three-level system is examined when the local random field is investigated further in the noiseless and noisy regimes. In~particular, we consider fractional Gaussian, Gaussian, Ornstein--Uhlenbeck, and~power law noisy regimes. We show that the destructive nature of the Ornstein--Uhlenbeck noise toward the symmetry of the qutrit to preserve encoded {purity and coherence} remains large. Our findings suggest that properly adjusting the noisy parameters to specifically provided values can facilitate optimal extended {purity and coherence} survival. Non-vanishing terms appear in the final density matrix of the single qutrit system, indicating that it is in a strong coherence regime. Because~of all of the Gaussian noises, monotonic decay with no revivals has been observed in the single qutrit system. In~terms of coherence and information preservation, we find that the current qutrit system outperforms systems with multiple qubits or qutrits using purity and von Neumann entropy. A~comparison of noisy and noiseless situations shows that the fluctuating nature of the local random fields is ultimately lost when influenced using the classical Gaussian noise

Cryptanalysis of 4-Pass HAVAL

HAVAL is a cryptographic hash function proposed by Zheng et al. Rompay et al and Wang et al found collisions of full 3-Pass HAVAL. In this paper, we study the security of 4-Pass HAVAL. We find collisions of full versions of 4-Pass HAVAL. The attack is similar to the two-block attack of MD5 proposed by Wang et al. The computational complexity of the attack is about 2^30-2^32 for the first block and 2^27-2^29 for the second block. We use this attack to find 256bit collisions of 4-Pass HAVAL in 3-4 hour on a common PC

A novel approach for seismic design of anchored sheet pile wall

Istraživanja oštećenih zemljanih konstrukcija nakon zemljotresa pokazala su da je ukotvljeni priboj (zagat) odlična seizmička konstrukcija. Međutim, zbog složenosti sustava naprezanja, neka temeljna teorijska pitanja još nisu potpuno riješena te teorijski razvoj konstrukcije zaostaje za primjenom, posebice u razvoju teorije seizmičkog proračuna. Kako bi se nadoknadio ovaj nedostatak, u radu se predlaže novi pojednostavljeni pristup, temeljen na prethodnom istraživanju. U tom se pristupu razmatrao učinak dinamičke sprege stup (pilon, šip) – zemlja – anker (zatezač), a postavljene su i odgovarajuće jednadžbe. Uz to, kako bi se provjerila primjenjivost predloženog pristupa, provedena su opsežna ispitivanja trešenjem (shaking table tests). U tim su ispitivanjima odgovarajuće primijenjeni omjeri sličnosti i slični materijali, a podaci o vremenu horizontalnog i vertikalnog ubrzanja zabilježeni na Wolong stanici tijekom Wenchuan zemljotresa u Kini, primijenjeni su za pobuđivanje modela. Dobiveni su mnogi podaci, uključujući dinamičke i ukupne pritiske zemlje koji djeluju na stabilizacijski stup, zategnutost užadi i pomake priboja. Usporedbom pritisaka zemljane mase i zategnutosti užadi dobivenih proračunom i ispitivanjima, dobio se koeficijent korelacije od 0,943 i 0,890 za pritisak zemlje, odnosno zategnutosti užadi. To pokazuje da se primjenom predloženog pristupa postigao visoki koeficijent korelacije od gotovo 1,0 između vrijednosti dobivenih ispitivanjem i teorijskih rezultata, pa je dokazano da je predloženi pristup prikladan za praktične primjene.From investigations of damaged earth structures after earthquakes, anchored sheet pile wall has proved to be an excellent seismic structure. However, due to the complexity of the stress system, some fundamental theoretical issues have not been completely solved, so the theoretical development of the structure lags behind application, especially in the development of seismic design theory. In order to make up for this deficiency, a new simplified approach was proposed in this paper, based on previous research. In this approach, the dynamic coupling effect of the pile–soil–anchor was considered, and governing equations were established. In addition, to verify the applicability of the proposed approach, large-scale shaking table tests were performed. In the tests, similitude ratios and similar materials were appropriately applied, and horizontal and vertical acceleration time histories recorded at the Wolong station in the Wenchuan earthquake, China, were used to excite the model. Many time history curves, including dynamic and total earth pressures acting on the stabilizing pile, the cable tensions and the displacements of the wall were obtained. By comparison of the earth pressures and cable tensions between the calculations and tests, the correlation coefficient is 0,943 and 0,890 for earth pressures and cable tensions, respectively. It illustrates that the correlation coefficient between tested values and theoretical results using the proposed theoretical calculation approach is high and close to 1,0, and it is proved that the proposed approach is suitable for practical application

A New Method to Analyze the Security of Protocol Implementations Based on Ideal Trace

The security analysis of protocols on theory level cannot guarantee the security of protocol implementations. To solve this problem, researchers have done a lot, and many achievements have been reached in this field, such as model extraction and code generation. However, the existing methods do not take the security of protocol implementations into account. In this paper, we have proposed to exploit the traces of function return values to analyze the security of protocol implementations at the source code level. Taking classic protocols into consideration, for example (like the Needham-Schroeder protocol and the Diffie-Hellman protocol, which cannot resist man-in-the-middle attacks), we have analyzed man-in-the-middle attacks during the protocol implementations and have carried out experiments. It has been shown in the experiments that our new method works well. Different from other methods of analyzing the security of protocol implementations in the literatures, our new method can avoid some flaws of program languages (like C language memory access, pointer analysis, etc.) and dynamically analyze the security of protocol implementations