I updated my iPad Air to iOS 8 and keychain not working correctly
Since iOS is a sandbox I do not know of any tools to help reset the keychain and download it again with out resetting all settings. Do you have the iCloud Keychain running, is it backed up via iCloud? If so then trying to reinstall your iCloud data back may fix the issue. Start by going to Setting> General>Reset reset all settings. If this does not work try  erase all content and settings and restore from and iCloud backup. If you are still acing issues the try a  full erase of the iOS and your data. Then restore from an iCloud backup.