The TSA mandates that all checked luggage must be locked with a deliberately flawed lock that can be opened with one of a handful of skeleton keys that are supposed to be kept secret. It's been more than a year since the TSA allowed a newspaper photographer to print a high-rez photo of its universal luggage-lock keys, allowing any moderately skilled locksmith to create her own set. Ars Technica downloaded a set of key STL files from Github, printed them on a consumer 3D printer, and showed that they could gain entry to any luggage.
It's a model for what happens with any kind of law-enforcement/public safety back door: the universal keys leak and there's no way to re-key all those locks out there in the field. The FBI and UK security services are calling for backdoors in all crypto — the code we use to protect everything from pacemakers to bank accounts. This is as neat an illustration of why that's a bad idea as you could ask for.
We've currently got a Buccaneer 3D printer on loan from the kind folks at Pirate3D, so we were all set to grab the files and go to work. The issue with the STL files in the GitHub repo is that they're not quite correctly scaled—they need to be sized up by a factor of 1.57 on the X and Y axes, and reduced to 0.64 on the Z axis. This is an easy fix with MeshLab or the 3D modeling application of your choice.
Actually producing high fidelity keys that worked took a day or so—it turned out that the number 2 key lacked a ward cutout needed to properly fit the number 2 lock, but the community quickly came to the rescue with a pull request. After fiddling with the keys' orientation on the print bed, we eventually wound up with our own Travel Sentry keyring—one that effortlessly unlocked both the Travel Sentry locks I had immediate access to.
Video: 3D printed TSA Travel Sentry keys really do open TSA locks [Lee Hutchison/Ars Technica]