An ESP32 can run a DIY FIDO2/U2F security-key project, but the available documentation does not verify a specific build that costs $6 or prove that it works like a YubiKey. A GitHub project lists ESP32-S2 and ESP32-S3 targets and requires USB-OTG-capable hardware. That is evidence a maker implementation exists—not evidence of the headline build’s parts cost, compatibility with particular accounts, or security equivalence.
What is verified about the $6 ESP32 build?
The exact build behind the headline could not be substantiated from the available sources: there is no confirmed parts list, firmware revision, test method, or account-service results. Treat “$6” and “actually works” as claims that need attribution to the original builder, not independently established facts.
A separate project, jocover/esp32_u2f on GitHub, describes creating a FIDO2/U2F token with an ESP32. It lists ESP32-S2 and ESP32-S3 as supported targets and says USB-OTG hardware is required. This establishes that a DIY implementation is documented; it does not verify the exact $6 device or its compatibility with any particular service.
Which ESP32 boards can support a DIY security key?
The cited repository names ESP32-S2 and ESP32-S3 targets, but the chip name alone is not enough to select a board. The board must provide USB-OTG capability, and its exact revision must match the project’s target-specific firmware and flashing instructions. The repository includes example flashing commands and identifies esptool as a tool.
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- Check the exact chip and board revision.
- Confirm USB-OTG support and the connector used for the USB connection.
- Follow the repository’s instructions for the selected target rather than assuming one ESP32 board’s firmware will work on another.
No specific board model or price for the headline build is established, so there is no verified bill of materials from which to confirm a $6 total.
Does an ESP32 security key work like a YubiKey?
“Works” needs a defined test. A firmware project that implements FIDO2/U2F does not, by itself, demonstrate successful enrollment or sign-in with a specific relying party, nor does it establish the behavior of the exact device in the headline. Those outcomes require dated test details identifying the firmware, hardware, services, and procedures used.
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Nor does implementing a related protocol make a DIY device equivalent to a commercial YubiKey. A meaningful comparison would need documentation about supported protocols, firmware maintenance, key storage and recovery, hardware protections, independent security evaluation or certification, relying-party compatibility, enrollment and backup, and total cost. The cited project descriptions do not establish those points for the $6 build.
What other ESP32 maker projects show—and do not show
The librekeys/pico-fido2 repository describes a separate USB passkey and OpenPGP smartcard project for Raspberry Pi RP235x or ESP32, with FIDO-related and OTP features. Its feature list is not proof of certification, independent security review, or equivalence to a YubiKey.
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A separate EvilKey project on Hackaday.io, created on September 26, 2026, describes an ESP32-S3 FIDO2 maker project using a Waveshare touch AMOLED board and adding an interface and other USB functions. It is an adjacent example, not evidence for the headline build’s hardware or cost.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What to check before relying on a DIY key
Before using a DIY device for important accounts, establish what its firmware supports and how the account provider accepts it. Check the project’s maintenance and security documentation, the device’s key-storage and recovery model, and whether you can enroll a separate backup authenticator. A feature list alone cannot answer those questions.
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Do not infer that a DIY ESP32 device has the same protections as a commercial key from the fact that both use FIDO-related protocols. The sources describe projects, not independent security evaluations of the headline device.
Quick Recap
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