An Open-Source Chip Built So You Can Check the Silicon With a Flashlight

Andrew "bunnie" Huang is going to hand DEF CON 34 attendees a flashlight and a piece of silicon and ask them to look inside. The Baochip-1x microcontroller, the chip powering this year's DEF CON hacker conference badges, is packaged so infrared light passes through the die instead of bouncing off an opaque plastic shell. A researcher can hold the chip up to an IR camera, see the transistor layers, and compare what is physically there against the design files Huang has already published on GitHub. The packaging is not a marketing feature. It is the answer to a specific problem the open-source chip movement has not, until now, solved.

A chip's design can be open from the transistor level up, but the moment that design is sent to a foundry, the buyer has to trust that what comes back is what was sent. A backdoor added in the fab, a substitution of a sub-block, a malicious modification that does not show up in the design files: these are the reason hardware supply-chain audits exist, and the reason "open source" has historically stopped at the schematic. Prior open silicon projects published their specifications and let researchers verify the design. The Baochip-1x is engineered so the silicon itself can be checked, in the hand, against the design.

Huang spent three years getting there. The microcontroller is described as "mostly" open: the operating system, firmware, processor core, cryptographic engines, and input/output system are all published and can be inspected. The "mostly" is the honest part. The radio-frequency block, the analog circuitry, and the foundry's process design kit, the proprietary recipe for how the chip is actually manufactured, are not. A reviewer can verify the digital logic. The rest of the chip is still on trust. That qualifier matters for anyone deciding what the Baochip-1x does and does not prove.

What it proves is a habit, not a guarantee. The infrared-transmissive packaging is a designer-stated property of the current chip; independent teardowns and datasheet inspection have not yet corroborated it at write time. The on-site demonstration at DEF CON this August is the moment that property moves from a Wired report's claim to something a researcher can do in front of an audience. If the inspection works as Huang describes, it sets a baseline: a chip whose published design and physical implementation can both be checked, in the same room, by the same person, with off-the-shelf IR equipment.

The badge itself is a runway for the demo, not the headline. DEF CON has a long tradition of turning its conference badge into an annual hardware curiosity, and this year's is the detachable Baochip-1x core module. After the conference, attendees can pull the module out of the badge frame and keep using it as a hardware security token. The token is where the chip's open cryptographic engines are meant to do real work, rather than sit on a conference lanyard. The badge gives the chip a built-in audience. The security token is the second life.

The Baochip-1x does not solve hardware supply-chain trust in general. It is one chip, one designer, one packaging choice. Foundries still run proprietary process steps. The radio and analog blocks still require trust. A determined adversary with access to the foundry's manufacturing line can still alter a chip in ways a post-fab IR check would not see. The honest reading is narrower and more useful: a working example of a chip whose physical silicon a reviewer can in principle compare to the published design, and a method other open-source silicon projects can copy.

Huang plans to demonstrate the technique at DEF CON this month. The on-stage IR inspection is the moment the manufacturing-stage trust gap stops being a property Huang says his chip has and starts being a property someone can point a camera at. What happens after, whether the method gets borrowed by other open-source silicon projects or stays a footnote on one conference badge, will be visible in the teardowns and follow-on work that arrive in the months after the conference.