keys = File.read("./dictionary.txt").lines.to_a.reverseThe author decided to show that if he knew all but one character of his network password, he could bruteforce the missing character. To that end, he took all 256 possibilities for that character, and computed the resulting keys. Then tried connecting with those keys.
This shows a connection rate of 30 attempts/2 minutes which is 0.25/second. That is not practical for most attacks.
Obviously there are some legal considerations in certain countries regarding development, possession and usage of such an application but the risk seems to be rather small if you restrict network services, change the MAC and use End-to-End encryption. Besides you might even get away with calling it a tool for penetration tests.