http://www.oxforddictionaries.com/us/words/the-oec-facts-about-the-language http://www.oxforddictionaries.com/us/words/the-oec-facts-abo... Well assuming rando

http://www.oxforddictionaries.com/us/words/the-oec-facts-about-the-language http://www.oxforddictionaries.com/us/words/the-oec-facts-abo... Well assuming random guessing with 95% vocabulary coverage its about 50,000 words. A passphrase checker that doesn't start from there but rather works from the ascii tokens is likely not very helpful for checking the strength of a passphrase. > ... should be 8 characters or longer, which forces you to use multiple words or extra symbols. > ... should have upper case, lower case, symbols, and numbers; or at least three of those four groups. > ... should not be a common word and should not be a common phrase. > ... should not contain a date, a name, or other things that can be associated with you. > ... should be created randomly or semi-randomly. > ... should not be a suggestion when you type in the first few characters into Google. As for your cited tester, you seem to have ignored every single piece of advice on the page and it seems it doesn't test for it in an automated way. I'd say, in this case, the problem is a bug in the tester rather than the truth of that being "safe". If you had followed the guidelines, yes, it'd likely be reasonably safe.