I am implementing file transfer using 1-to-1 chat and using the following link to implement it. http://ocsgcf.blogspot.com/ Using the mentioned approach I am able to transfer between two users. Now I am working to add encryption in this. I could not find any documentation on this. When I send file invite from my code to skype for business desktop client. It returns Encryption-Key and Hash-Key. Now I do not know how to use these keys in file transfer. Please advice.