CanoKey  is an open-source secure key with supports of
U2F / FIDO2 with Ed25519 and HMAC-secret
OpenPGP Card V3.4 with RSA4096, Ed25519 and more 
PIV (NIST SP 800-73-4)
HOTP / TOTP
All these platform-independent features are in canokey-core .
For different platforms, CanoKey has different implementations, including both hardware implementations and virtual cards:
In QEMU, yet another CanoKey virt-card is implemented. CanoKey QEMU exposes itself as a USB device to the guest OS.
With the same software configuration as a hardware key, the guest OS can use all the functionalities of a secure key as if there was actually an hardware key plugged in.
CanoKey QEMU provides much convenience for debugging:
libcanokey-qemu supports debugging output thus developers can inspect what happens inside a secure key
CanoKey QEMU supports trace event thus event
QEMU USB stack supports pcap thus USB packet between the guest and key can be captured and analysed
Then for developers:
For developers on software with secure key support (e.g. FIDO2, OpenPGP), they can see what happens inside the secure key
For secure key developers, USB packets between guest OS and CanoKey can be easily captured and analysed
Also since this is a virtual card, it can be easily used in CI for testing on code coping with secure key.
libcanokey-qemu is required to use CanoKey QEMU.
git clone https://github.com/canokeys/canokey-qemu
If you want to install libcanokey-qemu in a different place,
-DCMAKE_INSTALL_PREFIX=/path/to/your/place to cmake below.
make install # may need sudo
Then configuring and building:
# depending on your env, lib/pkgconfig can be lib64/pkgconfig
./configure --enable-canokey && make
Using CanoKey QEMU
CanoKey QEMU stores all its data on a file of the host specified by the argument when invoking qemu.
qemu-system-x86_64 -usb -device canokey,file=$HOME/.canokey-file
Note: you should keep this file carefully as it may contain your private key!
The first time when the file is used, it is created and initialized by CanoKey, afterwards CanoKey QEMU would just read this file.
After the guest OS boots, you can check that there is a USB device.
For example, If the guest OS is an Linux machine. You may invoke lsusb and find CanoKey QEMU there:
Bus 001 Device 002: ID 20a0:42d4 Clay Logic CanoKey QEMU
CanoKey QEMU consists of two parts,
the latter of which resides in QEMU. The former provides core functionality
of a secure key while the latter provides platform-dependent functions:
USB packet handling.
If you want to trace what happens inside the secure key, when compiling
libcanokey-qemu, you should add
-DQEMU_DEBUG_OUTPUT=ON in cmake command
cmake .. -DQEMU_DEBUG_OUTPUT=ON
If you want to trace events happened in canokey.c, use
qemu-system-x86_64 --trace "canokey_*" \ -usb -device canokey,file=$HOME/.canokey-file
If you want to capture USB packets between the guest and the host, you can:
qemu-system-x86_64 -usb -device canokey,file=$HOME/.canokey-file,pcap=key.pcap
Currently libcanokey-qemu.so has dozens of global variables as it was originally designed for embedded systems. Thus one qemu instance can not have multiple CanoKey QEMU running, namely you can not
qemu-system-x86_64 -usb -device canokey,file=$HOME/.canokey-file \ -device canokey,file=$HOME/.canokey-file2
Also, there is no lock on canokey-file, thus two CanoKey QEMU instance can not read one canokey-file at the same time.