Universal Windows Platform (UWP) application - Single Packet Authorization (SPA) client. SPA is an alternative to port knocking. See fwknop-tutorial for more details about Single Packet Authentication and fwknop.
This UWP client only supports AES (Rijndael) encryption and HMAC SHA-256 signing. Tested with fwknopd server 2.6.9 running on OpenWrt.
I did not publish this app to Windows Store. Just side-loaded to my devices. I may consider publishing in the future if there is a demand.
The interesting part (SPA data generation, encryption and signing) is here and it is a direct port of the fwknop-2.6.8 library.
Couple of screenshots just to give an idea of what it is:
