You can use fxor to encrypt your important files or just to play with OTP, Then code was written carefully as supposed to do with any crypto tool.
fxor tested on GNU/Linux and FreeBSD and OpenBSD.
FAQ: https://github.com/abderraouf-adjal/fxor/blob/master/FAQ
Github: https://github.com/abderraouf-adjal/fxor
Home page: https://abderraouf-adjal.github.io/fxor
OTP: https://en.wikipedia.org/wiki/One-time_pad