I’m not an expert in RustDesk, but I did take a quick look at the code, and it’s filled with massive red flags like [1], where it appears the general mechanism is SHA256(SHA256(password++salt)++challenge). I can’t even tell if the whole thing is vulnerable to trivial MITM ([2] makes it sound like it might be; while investigating, I ran into the concerning comment [3], “fall back to non-secure connection in case pk mismatch”). I can’t find any actual documentation of the protocol and it’s a custom thing built on NaCl boxes, yikes. [4] generates a keypair on the fly for a new connection to sign the box containing the symmetric key generated at the same time…

I would recommend never using this software.

[1]: https://github.com/rustdesk/rustdesk/blob/7aa98d43cf1962a7a2... [2]: https://github.com/rustdesk/rustdesk/discussions/8392 [3]: https://github.com/rustdesk/rustdesk/blob/7aa98d43cf1962a7a2... [4]: https://github.com/rustdesk/rustdesk/blob/7aa98d43cf1962a7a2...