Accelerating transitive closure of large-scale sparse graphs

Finding the transitive closure of a graph is a fundamental graph problem where another graph is obtained in which an edge exists between two nodes if and only if there is a path in our graph from one node to the other. The reachability matrix of a graph is its transitive closure. This thesis describes a novel approach that uses anti-sections to obtain the transitive closure of a graph. It also examines its advantages when implemented in parallel on a CPU using the Hornet graph data structure. Graph representations of real-world systems are typically sparse in nature due to lesser connectivity between nodes. The anti-section approach is designed specifically to improve performance for large scale sparse graphs. The NVIDIA Titan V CPU is used for the execution of the anti-section parallel implementations. The Dual-Round and Hash-Based implementations of the Anti-Section transitive closure approach provide a significant speedup over several parallel and sequential implementations

SHUFFLED INPUT GRAPHICAL PASSWORD AUTHENTICATION SCHEMES BUILT ON CAPTCHA TECHNOLOGY

When we consider the online service or desktop application there is major issue of security breaching. Old password schemes has some drawbacks like hacking of password, shoulder-surfing attack as far as password is concern, online password guessing attack, relay attack. Hence there must be system that provides good solution for such password cracking attacks. There are many solutions for it and various password schemes available that achieves this. The main drawback of these schemes is that users have to deal with complicated and tedious steps as far as registration and login of user is concern as its logic contains some intense AI processes. These complicated AI processes are exhaustive for common user of the system. In this paper we proposed authentication scheme which consist of graphical password based captcha challenge image. It consists of both a captcha and a graphical password schemes. We extend the use of captcha as human present recognition as well as graphical password hence it provides all benefits of captcha and make system more powerful from security point of vie