Why is OTP not vulnerable to brute-force attacks?
Brute force on OTP will give you all sorts of messages which are meaningful and not meaningful.

For example, you have a 4-character encrypted text: weaw. Now brute-forcing will give you all sorts of meaningful and not meaningful messages like:


erwe
hell
road
....


Now, which one was the real message? That would be difficult, rather impossible to guess.