نشریه منادی امنیت فضای تولید و تبادل اطلاعات (افتا)
سال سوم شماره 1 (پیاپی 6، پاییز و زمستان 1393)

The purpose of this paper is twofold: Study of the mathematical background on lattice theory and its applications to cryptography. In the latter area, lattice theory has played a crucial role in the definition of new cryptosystems, in the study of cryptographic primitives and in cryptanalysis. Lattice-based public-key cryptosystems relies on computational hard problems based on the shortest vector problem (SVP) and the closest vector problem (CVP) in lattices for their security. In this paper, we present a short introduction to lattice theory and its hard problems and also we study the most important lattice-based public-key cryptosystems and digital signature together with their security analysis and some applied examples.

In recent years, electronic payments has grown rapidly among internet activities so nowadays has attracted many customers due to its speed, efficiency, cost reduction and ease of access. Credit cards can be considered as one of the most widely used tools for electronic payments transactions . Purpose of this research is the identification and extraction feature of fraudulent transaction followed by correct classification of them into two categories of legal and fraud, using support vector machine algorithm and cross-validation. The results of ths method to show improvement in fraud detection so that false negative reduction has 77%, cost 88% and detection rate increased by 11%.

The suitable coverage, user access and data transmission with high speed are the most important properties in the new generation of telecommunication. In order to provide these properties, the interworking was introduced in 3 generation (3G). Moreover, 4 generation (4G) attend to this service more than the 3G. Different technologies have been presented for interworking, among which the WLAN is one of the most important ones. The 3GPP standard proposes six scenarios for the interworking. The user access, network architecture and protocol stack are based on these scenarios. This paper investigates the interworking, six scenarios and network architecture, and reviews previous works in interworking.

With the increase in attacks, the different mechanisms in different layers of defense are applied in order to detect and prevent attacks. In this case we are encountered with massive amounts of alerts with low level and scattered information. Alert correlation is one of the solutions that are used to combine alerts and create a high level view of under controlled network security situations, and a lot of researches have been done in this field. In this paper, we describe the OSSIM and introduce its features. In addition with a combined approach to the alert correlation problem, a new categorization is done on the scientific researches and with respect to these researches, we described the process of alert correlation in the OSSIM and established a correspondence between components of the OSSIM and one of the researches. In most researches the focus is on the alerts correlation of intrusion detection systems, we have shown in this paper that the other resources are effective in multi-stage attacks correlation.

The Cloud computing is a low-cost high performance model of computing services in response to the needs of users of Information Technology. Current security and privacy challenges in cloud environment have led to distaste some users and organizations to apply cloud instead of traditional infrastructures. Although many prevention efforts and acts are performed in current network architectures, detection and tracing of the attacker is necessary after the event is occurred. But current architecture of cloud computing does not satisfy the cloud forensics needs. Therefore, in this field the cloud forensic investigation have many different challenges. Regarding the low cost and high performance services of cloud computing, for the sake of security issues it can never be ignored. So far several solutions have been proposed regardingcloud’s security issues based on dynamic and elastic nature of cloud computing and legal issues. The main goal of this survey is to classify and and explore the cloud forensics issues and challenges.

A set of technologies, that use radio waves for identifying people or objects, is called radio frequency identification system or RFID. RFID performance depends on tag and reader devices which use radio waves to communicate to each other. In some applications of RFID systems, the proof of concurrent presence for a number of objects or persons together in a given time is crucial. Grouping proof protocols are designed to address these needs, in fact grouping proof shows that two or more tags are evaluated by a reader simultaneously. This proof must be verified by the corresponding verifier. In this article this type of protocols are introduced and analyzed. At the first, the idea of designing a grouping proof is presented and then related protocols and their security analysis are presented. Finally, a comparison between protocols is provided.