The Navy’s Unidirectional Network Graph
During the October 7th lecture, discussion of the web, as a graph, was opened. The course covered the ideas of links as they make all the nodes of the web graph interconnected. However, an important aspect of this notion is that links are one directional. In contrast to the edges that connect friends, which are two-way. Web links are connected via a one-directional hyperlinks; meaning that one web page links to another page but the latter page does not reciprocate the link. This is important to understand, especially when it comes to security and the ability of computers to communicate with other computers in a secure network.
For example, the United States Navy uses a proprietary program called the Navy Pump to connect computers on the military network. More specifically, the system allows a unidirectional edge to form from high security networks to low security networks. This allows networks that have a high security clearance to transfer information to computers that have less security clearance and may be at risk to cyber threats. Since the connection is one directional, high security computers can easily communicate with low security computers without the risk of the leaks.
This design is inherently asymmetric for intentional reasons. A computer higher up the security clearance graph should have access to associate with lower classified computers. However, as previously mentioned, those less secure computer do not automatically gain access. Therefore, low security computers never have access to data at free will, it requires a computer from the secure network to initiate the exchange. Thanks to the uni-directed graph design of the Navy Pump network, the US military is able to protect sensitive data by opening one direction portals to keep classified data secure.
Source: http://www.nrl.navy.mil/itd/chacs/sites/edit-www.nrl.navy.mil.itd.chacs/files/files/networkPumpBrochure_0.pdf