Exploring the Topological Properties of the Tor Dark Web

The web graph can be used to get insight into the internal structure and connectivity of the Tor dark web. This paper analyzes the internal structure of the Tor dark web graph and examines the presence of bow-tie structure as found in the World Wide Web. The web graph is generated from the data collected by the Python crawler customized to scrape data from the Tor dark web. Each of the nodes in the graph represents an individual Tor hidden service, and an edge denotes the hyperlink from one hidden service to the other. Various graph metrics are then computed and analyzed for both directed and undirected graphs using the Python NetworkX package. It was found that most of the nodes of the graph have in-degree and out-degree less than ten. The presence of power-law in degree distribution could neither be confirmed nor denied. The Tor web graph is sparse with a few connected pairs of nodes. Like the surface web, the dark web can also be decomposed into a bow-tie structure though with small component sizes. Several important and well-known websites on the surface web have incoming links from the dark web. Moreover, the Tor network also shows the characteristics of small-world and scale-free networks.