Sharif Digital Repository

Distributed Denial of Service (DDoS) is one of the more important attacks in computer networks. DDoS attacks can be categorized in to two categories: high rate and low rate. In the high rate DDoS category, the attacker tries to fill up all the link’s bandwidth capacity by flooding the link with packets. On the other hand, in the low rate DDoS category (i.e. LDDoS), the attacker executes a DDoS attack while keeping a low average transmission rate. TCP LDDoS is a low rate DDoS attack in which the attacker exploits the TCP congestion control behavior.
In this thesis, we investigate a system for defending against the TCP LDDoS attack and propose a novel method for doing so. We present some... 

Differential privacy provides a powerful definition for protecting data privacy by adding noise. Differential privacy mechanisms add noise to the responses of queries made to a database. Differential privacy challenges the learning of useful information from a dataset without leaking any information about the individuals present in that dataset. However, studies have shown that these mechanisms make assumptions about the data that, if not met, can lead to privacy leaks. One of these assumptions is the lack of correlation between data. If an attacker is aware of the correlation between data, common mechanisms cannot guarantee differential privacy.This thesis proposes a solution for adding...