Sharif Digital Repository

Anonymity helps in preserving user’s privacy in communication networks. In this respect many protocols with different characteristics have been proposed, as yet. Beside these protocols there have been introduced a lot of attacks, in which the ultimate goal is reducing the degree of provided anonymity. There is a class of attacks, where attacker tries to relate users of anonymity system to each other, just by observing execution of protocol. There is no need to compromise system’s nodes or even manipulating sent or received messages. Here, the attacker omits internal mechanism of protocol and assumes it has no vulnerability. The Statistical Disclosure Attack (SDA) is one of these attacks.... 

Vehicle Ad-hoc Network (VANET) is a type of mobile Ad-hoc network (MANETs) which vehicles are mobile nodes of this network and it can be used for various applications such as secure data sharing between vehicles, sending road information to vehicles, traffic controlling and reducing road accidents, also primary types of these networks are implemented in some systems such as “Waze” and “Balad”. On the other hand, if the security requirments are not provide in these networks, attackers can use this network to cause disruptions in this network, including intentional accidents, so providing security requirements in these networks seems necessary. Data authentication and preserving privacy of the... 

Today, ensuring privacy alongside other security features is essential for many services, and with the advancement of various technologies, different aspects of privacy are emerging. In most systems, establishing privacy is a challenging issue that may conflict with other system features or reduce the effectiveness of other system parameters. This dissertation studies privacy from the perspective of information theory in authentication as one of the significant security challenges. Applications of this issue include vehicular networks, sensor networks, and services based on blockchain technology. We consider various privacy features in the authentication problem, which includes a certificate...