On Aug 6, 2009, at 1:52 AM, Ben Laurie wrote:

Zooko Wilcox-O'Hearn wrote:
I don't think there is any basis to the claims that Cleversafe makes
that their erasure-coding ("Information Dispersal")-based system is
fundamentally safer, e.g. these claims from [3]: "a malicious party
cannot recreate data from a slice, or two, or three, no matter what the
advances in processing power." ... "Maybe encryption alone is 'good
enough' in some cases now  - but Dispersal is 'good always' and
represents the future."

Surely this is fundamental to threshold secret sharing - until you reach
the threshold, you have not reduced the cost of an attack?

Until you reach the threshold, you do not have the information to attack. It becomes information theoretic secure.

They are correct, if you lose a "slice, or two, or three" that's fine, but once you have the threshold number, then you have it all. This means that you must still defend the site from attackers, protect your media from loss, ensure your admins are trusted. As such, you have accomplished nothing to make the management of the data easier.

Assume your threshold is 5. You lost 5 disks... Whose information was lost? Anyone? Do you know? What if the 5 drives were lost over 5 years, what then? CleverSafe can not provide any security guarantees unless these questions can be answered. Without answers, CleverSafe is neither Clever nor Safe.


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