Sharif Digital Repository

One of the most intrinsic challenges of flash-based Solid State Drives (SSDs) is erasebefore-write limitation and the limited endurance of flash chips. Wear leveling and garbage collection are two mechanisms implemented in SSD’s controller to enhance endurance and performance. While wear leveling attempts to distribute erasures across all blocks in an even manner, it imposes a new security challenge on SSD,which leads to the presence of invalid data blocks in flash chips. Therefore, some data blocks that are logically deleted by the user are still available in flash chips and can be recovered by software or hardware recovery tools.
In this paper, a new criteria named vulnerability time... 

Reduction of security vulnerabilities is an important goal in software development process. Insufficient validation of application inputs is one of the spreading issues in security vulnerabilities matter. In our approach, we attempt to analyze an application code to find all potential vulnerable points which require validation, and offer some solution for preventing them from being exploited. In this thesis, we propose a framework to detect the application security vulnerabilities. Our framework focuses on validation vulnerabilities that caused by improper validation of user inputs. In this framework, a model of relations among the objects and elements of the application code is built and a... 

As the size and complexity of software increase, the number of software vulnerabilities also increases. An examination of vulnerability reports shows that in addition to the fact that a large number of unknown vulnerabilities still exist in software, there is still no proper solution for identifying vulnerabilities that have been observed one sample of them exit in real-world software. The main reason for such an event is the lack of a suitable template for recognized vulnerabilities, which ultimately makes searching for them in other software a problem of scalability and high search cost. This thesis, recognizing the importance of the issue, presents a framework for extracting robust and... 

Nowadays, power systems and substations are the most important components of the vital infrastructure of a country, which handle the production, transmission and distribution of the electrical energy. Automation systems increase the efficiency of the power industry while making remote control possible, but the use of computer-based control systems is a potential field for cyberattacks which may cause equipment destruction and electricity network destabilization. One of the main requirements for the utilization of digital substations is the synchronization between different equipment used in it. Several algorithms and protocols have been proposed so far for time synchronization in distributed...