Theory on where the Vita keys are kept
I am wondering if the reason we haven't found the Vita decryption keys is that they aren't stored anywhere in the PS3 firmware. I am wondering if they are only stored in the Vita's firmware and all the encrypting and decrypting is done on the Vita itself. I am guessing that Sony did this on purpose as they know that we can dissect the PS3 firmware and find anything in there. If the keys were there, we would have found them by now.
My guess is that the PS3 can't decrypt ANY Vita content as it would require the Vita keys and the PS3 simply doesn't have them.
My guess is that the only way we are going to find the Vita keys is to find an exploit in a Vita game but since there is no way to install a hacked Vita save file, we can't find it that way. We would probably have to find a special exploit in a PSP game that can be used to get out of the PSP sandbox. Maybe something similar to the way we got out of the GameCube sandbox on the Wii. That's way out of my league.
Sony's not perfect and they will make a serious mistake eventually. The only questions are when and will we find it? I guess there are people working on a custom Vita cartridge like what we use in the DS but I'm sure SOny did their homework to try to prevent such an attempt.
It's only a matter of time before the Vita falls just like every thing before it.
If it can be created, it can be hacked as nothing is perfect just like humans.