The DigiNotar root CA has been compromised and has been blacklisted by Mozilla and Chrome. I've already un-trusted their root CA in Keychain on my OS X devices, but how can I do something similar on my iPhone and iPad?
Edit: I'd like to do this without having to jailbreak any device.
Edit: The i0S 5 update from Apple removes the DigiNotar root CA from your iDevice and also gets rid of trust for MD5-signed certs. See this Ars Technica article for details.
Best Answer
You don't. (not without jail breaking iOS) More sadly, we've gone from the situation on iOS 4 -> 5 ->6 -> iOS 7 and still cannot choose what certificates are trusted by the OS.
This is either a bug in the iPhone configuration utility or an unimplimented feature. If you care, do reach out to apple to ask for this.
http://www.apple.com/feedback or http://bugreporter.apple.com
Unless you are comfortable writing a technically correct bug, the feedback link is a better avenue. Calling AppleCare or asking for this at the genius bar might also be worthwhile.