Krux is an open-source firmware that empowers users to create their own secure Bitcoin signing devices using readily available hardware, such as the Yahboom K210 module. Built for the Kendryte K210 chipset—a dual-core 64-bit RISC-V processor with 8 MB SRAM, AES, and SHA256 accelerators—Krux transforms devices like the Yahboom K210 into air-gapped tools for offline transaction signing. This makes it ideal for self-custody enthusiasts looking to secure their Bitcoin without relying on proprietary hardware.
Krux supports both single-signature and multisignature wallets, enabling offline signing via QR codes or SD cards using the PSBT (Partially Signed Bitcoin Transaction) format. It integrates seamlessly with third-party wallet coordinators for broadcasting transactions, keeping your private keys offline. The Yahboom K210, featuring a 2MP camera, 2-inch touchscreen, and TF card support, is a plug-and-play option, while DIY setups with Maix boards offer customization for tinkerers.
Recent updates to Krux (e.g., v25.03.0) include Taproot and Miniscript support, performance optimizations, and camera adjustments for the Yahboom’s GC2145 sensor. It’s a community-driven project, still unaudited, so use it at your own risk. Pair this setup with a Bitcoin price chart—hovering around $118,000 as of July 18, 2025—to highlight its real-world context. Ready to build?
On a following post we will cover the steps required to Flash Krux using the official installer and the Yahboom K210 module to create our signing device and start securing our Bitcoin today.
Thank you for giving your time to this post and hope that it has been useful to you and that it may have provided value, please share it with friend and family and if you feel so incline please drop me a few sats below it is greatly appreciated.
As always if you see anything that I may have gotten wrong and needs to be corrected please feel free to point it out by emailing me at [email protected]