This updated edition of Diffie and Landau’s text is a must-have for anyone who is interested in how encryption and communicative privacy politics have developed in the US over the past century or so. Privacy On The Line moves beyond a ‘who did what’ in politics, instead seeing the authors bring their considerable expertise in cryptography to bear in order to give the reader a strong understanding of the actual methods of securing digital transactions. After reading this text, the reader will have a good grasp on what types of encryption methods have been used though history, and strong understandings of the value and distinction between digital security and digital privacy, as well as an understanding of why and how data communications are tracked.

The only disappointment is the relative lack of examination of how the US has operated internationally – there is very little mention of the OECD, nor of European data protection, to say nothing of APEC. While the authors do talk about the role of encryption in the context of export control, I was a bit disappointed at just how little they talked about the perceptions of American efforts abroad – while this might have extended slightly beyond the American-centric lens of the book, it would have added depth of analysis (though perhaps at the expense of making the book too long for traditional publication). One of the great elements of this book is an absolutely stunning bibliography, references, and glossary – 106 pages of useful reference material ‘fleshes out’ the already excellent analysis of encryption in the US.

Ultimately, if you are interested in American spy politics, or in encryption in contemporary times, or in how these two intersect in the American political arena, then this text is for you.