Gnuk is an implementation of USB cryptographic token for GNU Privacy Guard. Gnuk supports OpenPGP card protocol version 2, and it runs on STM32F103 processor.
Cryptographic token is a store of private keys and it computes cryptographic functions on the device.
The idea is to separate important secrets to independent device, from where nobody can extract them.
See Development Environment for development environment for Gnuk. Gnuk is developed on the environment where there are only Free Software.
Hardware requirement for Gnuk is the micro controller STM32F103. In version 1.1.x, Gnuk supports following boards.