[jgrahamc]

"Your summary of Level 5 is not quite right - Level 5 is about storing separate chunks of ciphertext"

Ah, I see. So you generate hash H and using some private key K you calculate C(H,K) where C is some cryptographic algorithm and then you split C(H,K) into parts and spread them around.

So my scenario is complicated by the necessity to compromise K in addition to one of the places where bits of the C(H,K) is stored.

I still feel that the real security of this system relies on the difficulty of computing H.