MasterSecret implements Parcelable, secure?

[payload]

Hi. I was grepping the code for weird places to confirm if I can use TextSecure as my SMS replacement.

I saw that MasterSecret nulls out some buffer in its constructor where secretKey and macKey was residing. Is this because we don't want to leave some copy of the secretKey in freed memory? I guess so.

But than again MasterSecret gets copied around often in Parcel I think. For each Intent.putExtra and for the single MasterSecret.parcelClone call (why?). Why aren't these copies nulled out after use? Especially because Parcel comes from a pool with no documented scope.

[moxie0]

MasterSecret is for location encryption. It needs to be passed across binder calls. Attempts to "null out" immutable objects in Java will not end well. In general, attempting to clean or protect memory in the JVM is not really possible.