@node Precautions
@unnumbered Precautions

The very important precaution is the @strong{cryptographically good}
pseudo random number generator. GoVPN uses native operating system PRNG
as entropy source. You have no way to check it's quality in closed
source code operating systems, so it is recommended not to use them if
you really needs security. Moreover it is possible that those OS leaks
information about possible PRNG states. And at least Apple OS X and
Microsoft Windows are already known to have weak CSPRNGs.

GoVPN could use it's own PRNG implementation like
@url{https://www.schneier.com/fortuna.html, Fortuna}, but it is
much easier to use the right OS, to use free software.

Also you should @strong{never} use one key for multiple clients. Salsa20
encryption is randomized in each session, but it depends again on PRNG.
If it fails, produces equal values at least once, then all you traffic
related to that key could be decrypted.