It’s been a longtime feature of the annual Defcon hacker conference that attendees come away not only with knowledge of new software vulnerabilities and hacking techniques but also an elaborately designed conference badge—often electronic masterpieces embedded with intricate puzzles, complex crypto challenges, hidden Easter eggs, and even the mechanical gear trains of a watch.
Each year’s badge creator endeavors to top previous designs and blow the minds of hard-to-impress hackers. But this year’s badges take a different tack. Instead of the badge designs being the star, it’s what is inside the hardware that will really stand out.
This year, Defcon asked legendary hardware hacker Andrew “bunnie” Huang to create the badges—revealed here for the first time—and they include an innovative open source chip that Huang designed and that aims to do no less than advance the state of security, transparency, and trustworthiness in computing.
But the chip isn't just part of the badge. Its core module can be removed and used after the conference as a hardware security token, giving the badge a second life beyond Defcon.
The chip—called the Baochip-1x—is a “mostly” open source microcontroller that has been three years in the making and fulfills Huang’s years-long dream of making a chip whose security is verifiable. Huang has published the source code for the Baochip’s operating system, firmware, processor core, cryptographic engines, and input-output system, on GitHub, making these components available for inspection and use.
The chip is also packaged so that researchers can peer inside to check the silicon itself and compare what they see against the published design, rather than having to trust that the manufactured chip is what the designers intended.
Computer chips are traditionally black-box components with an opaque casing that obscures their circuitry. Even previous open source chips that made their specs and code available for users to examine were encased in impermeable plastic, creating a supply-chain problem. Users had to trust that nothing changed during the manufacturing stage of the chip, such as a backdoor component being added to it.
Unlike conventional chips encased in opaque plastic, the Baochip is packaged so that infrared light can be shone through the back of the silicon, allowing the chip's internal structures to be visually inspected.
Huang plans to demonstrate the technique at the conference, allowing attendees to inspect the chip under an infrared light.
“I've been doing a bunch of stuff along the lines of trust and silicon and verification transparency” for years, Huang tells WIRED. "It's all … this kind of story arc I've been on … to try and get a chip that we can trust down to the very core, down to the transistor … You can actually … see the RAM arrays … on the chip.”
Build-a-Chip
Building a new chip is an expensive project that can cost millions of dollars for fabrication. But Huang got a big break three years ago when a company called Crossbar reached out to him. The company wanted to create a new open source and secure chip but didn’t know how to go about it. Huang agreed to assist on one condition: that they let him piggyback on their manufacturing run by placing his CPU on their chip wafer, allowing both designs to share the same manufacturing run rather than requiring Huang to fund a separate run.
"They look at it as, if they put me on the chip, they get two products for the price of one,” Huang says. This kind of piggybacking is not unusual, he adds, though it’s not something the industry likes to discuss publicly.
The result is a Crossbar chip that includes both Crossbar’s microprocessor and Huang’s. The Baochip is essentially the same chip but with the Crossbar microprocessor disabled, since Huang doesn’t have the rights to distribute it.
The Crossbar version of the chip uses a proprietary ARM core, whereas Huang’s version uses a RISC-V core whose implementation is open source. The RISC-V instruction set is also open and publicly documented. The two versions can use the same underlying infrastructure and peripherals while activating different CPU cores.
There are some closed-source elements on Huang’s chip. Some low-level physical-design and manufacturing elements, including those associated with TSMC's 22-nanometer fabrication process, are proprietary. “But … if you look on the spectrum of how open you can get things, this is … very, very far beyond any [other] security-oriented chip,” Huang says.
Badge Beginnings
Past Defcon badges have used commercial off-the-shelf chips rather than custom-designed open source silicon. The idea for using the Baochip was sparked by a meeting late last year when Huang spoke with Defcon founder Jeff Moss about his progress in developing his open source chip. He told Moss that he planned to release it this summer through his company, Baochip.
Moss realized the concept behind it matched perfectly with the conference theme this year—agency—which Defcon defines as the technologies we use and the choices we make that increase self-determination. And he and Huang realized it would be a great opportunity to help bootstrap the chip’s adoption. Until now, the Baochip has been distributed only in a small development release; the 27,000 Defcon badges represent its first major distribution.
Moss had one requirement for the badges. He wanted them to have a life beyond the conference and not be something that people would just throw in a drawer or a landfill after the event. He’s long been frustrated with the design and limitations of hardware security tokens and crypto wallets that, at the hardware level, can be cracked, so he thought Huang’s chip could be a more secure alternative to existing authentication tokens and wallets.
"I've always kind of dreamed of this idea where you can take your secrets, put them in hardware, and then if an attacker gets in, they can't quite get your secrets,” Moss tells WIRED.
The badge's detachable module can serve as a FIDO hardware security token. Its software supports time-based, one-time password systems and password management. Huang says it is "probably the world's first open source security token that you can fully inspect all the way down to the bootloader [and] transistors.”
The removable module also includes a camera for scanning QR codes to register them to authentication systems. But in keeping with Defcon’s privacy practices and its ban on surreptitious photography at the conference, the camera is very low resolution and nearsighted, and the chip by default only utilizes the black and white data from the camera and doesn’t support photo storage.
"It's … great at scanning QR codes and pretty much bad at everything else,” Huang says.
The badge doesn’t eschew conference life. Huang still included features designed to encourage attendees to interact. The badges, for example, have LED lights that flash in different color palettes and patterns depending on the type of badge—there are different ones for general attendees, speakers, and goons (the small army of volunteers who run the conference) as well as the special black Uber badges that go to contest winners and special VIPs, which give them free Defcon attendance for life. Each badge type starts with a specific color and flashing pattern, but users can add to their colors and build more complex flashing patterns when their badges communicate with other badges.
How Secure Is It?
The chip runs an operating system written in Rust and includes secure boot, a true random number generator, and hardware features intended to harden it against attacks. Huang believes it will be particularly resistant to remote, nonphysical attacks.
The chip also uses resistive RAM, or RRAM, a type of nonvolatile memory that Huang says is designed to make physical extraction of stored data more difficult than conventional flash memory. With flash memory, he says, "if you de-layer it down to the actual flash cells … you can just see the ones and zeros literally on these chips.”
Huang is cautious, however, about overhyping the chip’s security capabilities. He estimates that it could withstand attacks involving tens of thousands of dollars in resources, but says an adversary with millions of dollars and a sophisticated hardware-analysis lab could likely defeat it.
“I actually think it's one of the most secure chips you can get out there, but I [also] think most chips have been oversold in terms of security,” he says.
Huang says he likes the fact that the chip will be stress-tested by Defcon attendees and knows they will likely hack them and expose flaws that will help him make them even more secure.
"I fully expect there will be zero-days [that people find in the code]. It's actually … one of the features … of launching at Defcon,” he says of designing an open source chip capable of being examined.
Today the chip can function as a YubiKey-like security token; but in the future, he says, it could become an HSM or run other software such as Linux. The hardware uses a 350 MHz RISC-V processor with 2 megabytes of SRAM and 4 megabytes of RRAM, which he says puts it “on the edge of being able to run Linux,” and it has 4x 700MHz PicoRV32 cores for doing input-output. It already runs MicroPython and has C and Rust development kits.
Huang plans to expand the chip’s features himself, but he also expects DefCon participants to build on what he’s provided and make the chips their own.
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