"I've been denied entry to the US essentially for carrying my trainings material. Wow.
It appears I can't attend Blackhat this year. I was denied entry to the US for carrying trainings materials for the Blackhat trainings, and intending to hold these trainings as a private citizen instead of as a company.
After a 9-hour flight and a 4 1/2 hour interview I was put onto the next 9-hour flight back to Germany. Future trips to the US will be significantly more complicated as I can no longer go to the US on the visa waiver program.
A little background: For the last 7 years, I have attended / presented at the 'Blackhat Briefings', a security conference in the US. Prior to the conference itself, Blackhat conducts a trainings session, and for the past 6 years, I have given two days of trainings at these events. The largest part of the attendees of the trainings are US-Government related folks, mostly working on US National Security in some form. I have trained people from the DoD, DoE, DHS and most other agencies that come to mind."