A program for secure file sharing

The program is a client-server system where users can join and exchange files and messages with other users. At the same time, it is guaranteed that each file will be completely encrypted with a synchronous algorithm (Idea 128 bit) during transmission. The exchange of private keys is carried out using an asynchronous algorithm (you can choose any, the implementation will not change). The project was implemented back in 2017, when messengers could not yet boast of direct encryption.