How secure is it to use a password hash of a common English word as a WPA2 key?

"Unless you reveal the method of how you generated your ""long WPA2"" key (which you just did), it's just a complex hexadecimal string which would normally be pretty secure. On the other hand, if someone knew that you were using ""a common English word"" and used a hash of that word as the key, anyone could quickly regenerate a sequence of hashes from a dictionary and use it as a rainbow table to break your password pretty quickly.

If you are looking for a ""difficult password that is still easy to remember"" why don't you come up with a longer pass phrase that means something to you but not easily guessed by anybody else. That would render widespread rainbow tables essentially useless. Start with a phrase (i.e. sequence of words, sentence, etc), mix in a sequence of digits that means something to you (avoid birthdays, phone numbers, etc), and generate a long key that is ""easy to remember"" that way."

"It is safe as long as nobody can possibly figure out the method. This of course includes bragging about it in the office, but also traces of any kind you may leave behind. As an example, if you are to connect a random user to your network, you'll probably use some kind of client-side application to generate the hash. If the random user then notices that there's an echo ""superuser"" | sha1sum in the log it's not too hard to add the two together.

Seeing as you'd have to generate the hash externally, much of the convenience disappears. Generally I'd say that hashing a common word might be an acceptable way to quickly generate a semi-random key, but the key must still be copied or remembered when entering to not pose a weakness.

The only other gain I can think of is that the key/phrase/password can be easily reproduced if lost. If above security-measures are taken I see no reason not to use hashed words as keys."