I\'m in early (pre-coding) stages of developing a mobile web application using jQuery Mobile (we looked at Sencha Touch for a few weeks, but jQuery Mobile is a better fit for ou
The KeyChain solution would work only on iOS devices, so if that's your only target you are fine.
But what about the others? Kind of a waste using PhoneGap but then deploying only to one framework...
I know localStorage is not secure, but if you are aware of the limitations there are ways to make a bit less "obvious".
Here's the jQuery.handleStorage plugin which also handles AES encryption... You could have a look at the source and implement only the parts you need (in case you don't want to use the whole plugin, which also supports desktop browsers!).
PS: I am not affiliated in any way to that plugin or the author