I've always found that it's better to ask for forgiveness than permission in a large bureaucratic technically simplified corporation, otherwise I'd get nothing done. Ask, and they say "no".
Yes, that Randall Schwartz.
And no blame, but it's probably a good idea to say, "We're scanning for weak passwords" first. The sysadmin at the library I used to work at ran password crackers occasionally, and sent out an e-mail once saying that he suddenly knew a lot of staffs' boyfriends names. It's a delicate issue.