Keycard Blog

A reproducible build means that anyone can take the published source code of a hardware wallet's firmware, compile it with the documented toolchain, and get a binary that is bit-for-bit identical to what the vendor ships. This matters because it is the only way to verify, rather than trust, that the firmware running on your device matches the code you can read and audit. Without it, open source is a transparency gesture rather than a security property. What a reproducible build actually proves