I would like to acknowledge the many people from whom I have learned cryptography and PKI over the years, especially the technical wizards at VeriSign.

Some 30 years ago, a friend of mine, Winn Schwartau, who has run many Information Warfare conferences over the years, approached me with an opportunity to make the communication software I had created for CP/M and MSDOS encrypt files and chat for the US IRS. We actually delivered a working product (which used a hardware DES board), and they accepted it. Unfortunately, congress never authorized funding for this, so it was never deployed, and the IRS continued sending sensitive financial information in plaintext over phone lines via modems for some time. Hopefully, they fixed this somewhere along the way! However, this got me started in the fascinating field of cryptography (using DES at the time).

I also learned a lot about cryptography from a great book on the subject, Applied Cryptography, by Bruce Schneier (one of my favorite authors on computer security). Thanks for the insight and knowledge, Bruce!

In 1998, I was working for a computer security company called SecureIT, founded by Jay Chaudhry (now CEO of Zscaler). We did white hat hacking plus firewall consulting and training. One of our customers was VeriSign. We made it further into their layers of security than anyone else, and they apparently decided we were safer on the inside than on the outside, so they bought us. They thought since we made great training for CheckPoint Firewall-1, we would be able to make equally great training for cryptography and PKI. Unfortunately, the two areas are quite different and the attempts by our firewall trainers did not go well. I was not a trainer, but I offered to try, since my degree was in math and I had learned at least some cryptography in the IRS project some years before. VeriSign loved what I came up with, and I spent the next two years traveling all over the world, teaching PKI to large customers and affiliates.

Since I was creating the training, I was allowed to ask anyone at HQ any question, and they were required to answer. I was “drinking from a firehose,” learning from literally the top people in the field. I also did very well there with Incentive Stock Options. Those helped me to co-found CipherTrust in 2000 (again with Jay Chaudhry), where I applied much of the technology I had learned at VeriSign.

I would also like to acknowledge the contributions of my two technical reviewers who have made this book better, more technically correct, and easier to understand.

The first half was reviewed by Merike Kaeo. I have known her for some 20 years and consider her one of the top people in the computer security field. She is also a senior advisor at my venture in Singapore, Sixscape Communications Pte Ltd. I am very honored that she was willing to spend some of her valuable time reviewing the first half.

The second half was reviewed by one of my students from my VeriSign days, Hans van de Looy. He is based in the Netherlands and was working for a networking company called Pink Roccade when I met him in my VeriSign training classes there. He is also an elite (white hat) hacker and is well known at DefCon and Black Hat Briefings.