World War II emphasized the strategic importance of computation, communication, and information. There was unprecedented investment in the development of new technologies during the war. We start with Alan Turing and others at Bletchley Park.

In the 1960s and 1970s, there was a great deal of research done to build the first wide-area packet switched networks for the US Department of Defense. In the 1980s, the first “Internet” was formed to allow academic researchers to access supercomputer resources.

The World-Wide-Web was invented in 1990 but it was not an overnight success. But by 1994 - “the year of the web” - the web was being widely used and Internet usage was growing by leaps and bounds.

The late 1990’s saw the web and Internet used increasingly to revolutionize how business was done. Companies like Amazon were founded and grew very rapidly.

The Internet is designed based on a four-layer model. Each layer builds on the layers below it. The Link and Internetwork layers are the lowest layers of that model.

The Transport layer is built on the Internetwork layer and is what makes our network connections reliable.

With reliable “pipes” available from the Transport layer, we can build applications like web browsers, file transfer applications, or email clients and servers.

Using simple examples, we examing how to shield data from prying eyes and make sure that the data was not altered while in transit.

We apply the basic ideas of encryption and signing to who we actually secure the connections that we use on today’s Web and Internet.