When designing secure systems, electronic commerce, Internet of Things, social media, smart homes, industrial control systems, and distributed systems overall call for security protocols, often also called cryptographic protocols, to secure the exchanges between the network nodes. This Festschrift is a set of 23 essays dedicated to Joshua Guttman's 66.66th birthday. Granted, this book was published in December 2021, but aren't we all playing catchup in this post-pandemic era? It is still timely today.

The editors of this Festschrift collected 23 essays from authors in the field of formal methods for protocol analysis, an area that has been touched upon in this set of book reviews a few times. For those who are interested and new in the field, I urge you to pick up those other books as a basic introduction, if need be.

Spread over 425 pages with 65 black and white illustrations and with a preface by the editors, this book provides access to a higher ground in this field of formal methods. The authors who wrote these essays are themselves in the right position to comment on Joshua Guttman's contributions, which include the concept of "Strand Spaces" for protocol analysis. Of course this field is close to my heart. What does it mean that a protocol is secure? How do we express it? What concepts are needed to describe the minute differences that shield the information from the attackers, the evil adversaries Eve and Mallory that intrude upon Alice and Bob? What granularity is needed to express the security guarantees, the lack thereof, the attacks that have already been performed, and the ones we will discover tomorrow?

These 23 essays are self-contained contributions, as an homage to Joshua Guttman, that describe how influential his work has been, but also where the work went to next. Applications to modern concepts, such as smart home environments called Node-RED, blockchain, security domains, prototyping formal method tools, value of privacy in federated data trading, are represented here. For those who are familiar with the field, these are delightful departures into new corners. And for those who are new to the field, perhaps this is a motivation to delve deeper into an area that brings together a few disciplines to make things work just right. I remember walking down the aisles of a bookshop in the DC area with some of these experts mentioned here, picking up various mathematics books off the shelves that illustrated some basic concepts needed to perform various forms of protocol analysis.

Each essay is, as previously mentioned, self-contained and has its own bibliography, so one can enjoy each one of them as a "bonbon," e.g. to savor as your bedtime reading. While they are anything but introductory, these essays do provide explorations of the field of protocol analysis, a thorough checkup of the primitives that make up the building blocks of our "secure systems" we create today. One such essay I will highlight: Sylvan Pinsky's reference to Joshua Guttman's pioneering of strand spaces, which allowed showing whether security protocols are correct, is an homage to his work. Another essay talks about explaining security protocols to your children. There is an essay for everyone in this collection.

Overall I liked reading this collection of essays: the curation by the four editors, assembling these works from knowledgeable contributors in this protocol analysis field, is different from simply picking a few papers and stapling them together. Joshua Guttman, someone I had the pleasure of meeting many years ago at the Protocol Exchange meetings in the DC area, sometimes held at the National Cryptologic Museum right outside of "The Agency," as a few call the National Security Agency, deserves all the credit he gets in this Festschrift. It shows the impact Joshua Guttman has made, the inspirations he has created and continues to make.

I hope you will enjoy reading this Festschrift as much as I did. My copy will find its permanent space on my bookshelf.

Sven Dietrich reviews technology and security books for IEEE Cipher. He welcomes your thoughts at spock at ieee dot org