It's not clear from the context if you mean to say that's simple or hard with that link.
A OTP might be mathematically simple, but logistically it's very hard - you have to safely distribute the key and that key must be at least as long as the message you're passing.
A OTP might be mathematically simple, but logistically it's very hard - you have to safely distribute the key and that key must be at least as long as the message you're passing.