Al-4.5Cu-2Mg合金应力-应变定位及分布的有限元分析（英文）

通过有限元方法分析不同加工路线和条件对Al-4.5Cu-2Mg合金微观形变行为的影响。合金采用4种不同的加工技术和条件制备,分别为有或无细化剂的常规重力铸造、流变铸造和SIMA工艺。以合金的光学显微结构作为代表性体积元(RVEs),采用两种不同的边界条件模拟合金在单轴载荷作用下的变形行为,最后将模拟的应力-应变行为与实验结果进行比较。结果表明,微观结构形态对应力和应变分布及承载能力具有显著影响,共晶相比α(Al)相能承受更高的载荷,具有较薄且均匀分布的共晶网络结构的球状α(Al)相能提供更好的应力和应变分布。因此,SIMA加工合金比其他技术加工合金拥有更好的应力和应变分布。最后,将该合金的模拟屈服强度与实验进行验证,结果具有较好的一致性。     

Multi-party semi-quantum key distribution-convertible multi-party semi-quantum secret sharing

This paper proposes a multi-party semi-quantum secret sharing (MSQSS) protocol which allows a quantum party (manager) to share a secret among several classical parties (agents) based on GHZ-like states. By utilizing the special properties of GHZ-like states, the proposed scheme can easily detect outside eavesdropping attacks and has the highest qubit efficiency among the existing MSQSS protocols. Then, we illustrate an efficient way to convert the proposed MSQSS protocol into a multi-party semi-quantum key distribution (MSQKD) protocol. The proposed approach is even useful to convert all the existing measure–resend type of semi-quantum secret sharing protocols into semi-quantum key distribution protocols.     

PFC-CTR,PFC-OCB: Efficient stream cipher modes of authencryption

Authencryption is a cryptographic process of providing confidentiality and integrity protection of messages in a single pass, simultaneously, without any support of conventional checksum, MAC, or hash function. This article encompasses the process to construct the stream cipher-based authencryption environment, where the keystream is generated from any secure block algorithm like AES. Accordingly, in order to demonstrate the working principle of authencryption in the stream cipher environment, the authors introduce two stream cipher modes of authencryption, namely, PFC-CTR and PFC-OCB. PFC-CTR denotes the counter-based authencryption environment, and PFC-OCB specifies the authencryption environment built upon the underlying foundation of OCB. They argue that both of the proposed stream cipher modes of authencryption are quite robust against several active attacks (e.g., message stream modification attacks, known-plain-text attacks, and chosen-plain-text attacks). At the same time, they can efficiently deal with other issues like “limited error propagation,” and so on, existing in several conventional stream cipher modes of operation like CFB, OFB, and CTR.     

Finite element analysis of stress–strain localization and distribution in Al-4.5Cu-2Mg alloy

Finite element analysis has been carried out to understand the effect of various processing routes and condition on the microscale deformation behavior of Al-4.5Cu-2Mg alloy. The alloy has been developed through four different routes and condition, i.e. conventional gravity casting with and without refiner, rheocasting and SIMA process. The optical microstructures of the alloy have been used to develop representative volume elements (RVEs). Two different boundary conditions have been employed to simulate the deformation behavior of the alloy under uniaxial loading. Finally, the simulated stress–strain behavior of the alloy is compared with the experimental result. It is found that the microstructural morphology has a significant impact on stress and strain distribution and load carrying capacity. The eutectic phase always carries a higher load than the α(Al) phase. The globular α(Al) grains with thinner and uniformly distributed eutectic network provide a better stress and strain distribution. Owing to this, SIMA processed alloy has better stress and strain distribution than other processes. Finally, the simulated yield strength of the alloy is verified by experiment and they have great agreement.     

Provably Secure Mutual Authentication and Key Exchange Scheme for Expeditious Mobile Communication Through Synchronously One-Time Secrets

The Universal Mobile Telecommunication Standard (UMTS) is continuously evolving to meet the increasing demand of modern mobile and Internet applications for high capacity and advanced features in security and quality of service. Although admittedly enhanced in terms of security as compared to GSM (2G) systems, UMTS still has some weaknesses that may often lead to several security incidents. In this article, we come up with a novel authentication mechanism based on the one-time-secret security capabilities, which can assure an expeditious mobile communication environment and simultaneously be able to deal with the several issues related to security vulnerabilities (Redirection Attack, Man-in-the-Middle-Attack) and others like the excessive bandwidth consumption, storage overhead in VLR etc. existing in the current mobile communication (UMTS). In addition, here we also introduce a new concept called “Neighborhood Policy”, where several VLRs can form groups among themselves and carry out significant responsibilities in order to authenticate a User without interfering HLRs even though the User moves to a new VLR (belongs to the same group). We argue that the proposed solution not only achieves the mutual authentication in a secure manner, but at the same time, it also greatly reduces the computation and communication cost of the mobile User as compared to the existing state of the art authentication schemes.     

Efficient authentication protocol for secure multimedia communications in IoT-enabled wireless sensor networks

Multimedia Tools and Applications - In current times, multimedia application includes integrated sensors, mobile networks and Internet-of-Things (IoT) services. In IoT services, if more devices are...     

Anonymous and expeditious mobile user authentication scheme for GLOMONET environments

The Global Mobility Network (GLOMONET) is rapidly becoming important as well as a popular feature in today's high‐performance network. The legal mobile users enjoy life using the ubiquitous services via GLOMONET. However, because of the broadcast nature of the wireless channel, providing user authentication along with the privacy and anonymity of the users in GLOMONET is indeed a challenging task. In this article, we come up with a secure and expeditious mobile communication environment using symmetric key cryptosystem to ensure mobile users' anonymity and privacy against eavesdroppers and backward/forward secrecy of the session key. Our scheme can also protect numerous security threats, like man‐in‐the‐middle attack, known session key attack, lost smartcard attack, and forgery attack. Furthermore, we put forward a new technique named as “friendly foreign agent policy,” where many foreign agents can make different groups among themselves and perform important responsibilities to authenticate a legitimate mobile user without interfering his or her home agent even though the mobile user moves to a new location, covered by a new foreign agent (belongs to the same group). Security and performance analyses show that the proposed scheme is secure and more efficient as compared with other competitive schemes for GLOMONET environments.     

RT-OCFB: Real-Time Based Optimized Cipher Feedback Mode

Several modes of operation have been built upon block cipher security. Among them, CFB is considered to be one of the popular modes of operation because of its self-synchronizing property. Besides, appearance of OCFB makes CFB even more competitive. However, because of the stalling problem (i.e., there is a need to stall while doing block encryption) and the inability to arrange the keystream in advance, both the CFB and OCFB modes are considered to be inadequate for such real-time applications, where the appearance of inputs is expected to be uniform. In this article, researchers present a new mode of operation based on the underlying foundation of both the CFB and OCFB modes of operation, called real-time based optimized cipher feedback mode (RT-OCFB), which remedies this problem. They also argue that the proposed mode of operation (RT- OCFB) holds the similar imperative security properties as CFB and OCFB, which are indeed essential for modern cryptography.     

Microstructural evolution and hardness property of in situ Al–Mg2Si composites using one-step gravity casting method

In the present investigation, Al–X?wt-% Mg₂Si (X?=?0, 5, 10, 15 and 20) in situ composites are successfully synthesised by one-step gravity casting technique. Commercially pure Al, Mg and Si are used as raw materials. Microstructural evaluation and correlation of micro- and bulk hardness properties have been studied on developing composites. The composites consist of mainly three phases: matrix (α-Al), reinforcing (primary Mg₂Si) and binary eutectic (Al–Mg₂Si) phase. Primary Mg₂Si particles are formed by pseudo-eutectic transformation during solidification and surrounded by matrix and binary eutectic phase. It is found that Mg₂Si concentration has a significant impact on morphology and volume per cent of the above-mentioned phases. Primary Mg₂Si particles’ size and volume per cent increase with increasing wt-% of Mg₂Si. Volume per cent of individual phases and Mg₂Si concentration have great impact on hardness properties of composites. Bulk hardness increases with increasing wt-% of Mg₂Si concentration, but micro-hardness of primary Mg₂Si particle decreases slightly. Mg₂Si concentration also has significant impact on micro-hardness of individual phases.     

An enhanced secure delegation-based anonymous authentication protocol for PCSs

Rapid development of wireless networks brings about many security problems in portable communication systems (PCSs), which can provide mobile users with an opportunity to enjoy global roaming services. In this regard, designing a secure user authentication scheme, especially for recognizing legal roaming users, is indeed a challenging task. It is noticed that there is no delegation-based protocol for PCSs, which can guarantee anonymity, untraceability, perfect forward secrecy, and resistance of denial-of-service (DoS) attack. Therefore, in this article, we put forward a novel delegation-based anonymous and untraceable authentication protocol, which can guarantee to resolve all the abovementioned security issues and hence offer a solution for secure communications for PCSs.