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by swordswinger12 3289 days ago
The original goal of the academic "encrypted database" proposals like CryptDB was security against this kind of adversary. The idea was that if all the data is encrypted even when you're querying it, you get some security against a compromised OS. Unfortunately, in this paper we showed even this "always encrypted" approach has many subtle flaws that leave the data vulnerable to inference attacks.
1 comments
Ar-Curunir 3289 days ago
It's much better than what is out there in industry, however: plaintext data. Usually the attacker when you upload data to the cloud isn't the cloud provider, but outside intruders.

I feel it's not constructive to claim that solutions that provide intermediate security are useless; schemes that provide strong security (eg. ORAM based schemes) are far from practicality, and so these intermediate security solutions are the best we've got.

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swordswinger12 3289 days ago
To be clear: nowhere in this paper did we claim any particular solution is useless. However, the degree to which these systems are useful, and what situations they are useful for, is not well-understood. Prior work has shown that the encryption used in many of these systems is breakable (i.e. the plaintext is recoverable with near-perfect accuracy) with simple attacks. See, for example, this recent paper (https://eprint.iacr.org/2016/895) on cryptanalysis of order-revealing encryption.

Respectfully, I find this "more secure stuff is slow so we have to live with what we've got" argument to be specious. There simply is no evidence that a fast encrypted database must also provide very weak confidentiality guarantees.

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Ar-Curunir 3289 days ago
The evidence lies in the failure of the cryptographic community to provide a solution with strong security properties that is performant. For example, nobody has even attempted an ORAM-based database system. We also do not have schemes that can efficiently provide an intermediate level of security, between "weak" and "strong" systems.

Either way, as I said earlier, it's a question of threat models. Most cloud users trust Google and Amazon. These companies also have strong intrusion detection capabilities, so with non-negligible probability an outside attacker would be detected within a reasonable amount of time. In such a scenario, it is better to have some protection than none at all.

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swordswinger12 3289 days ago
The failures of the academic cryptography community to provide solutions to real-world problems in general are well-documented, and I will not belabor them here (q.v. Rogaway's "The Moral Character of Cryptographic Work").

I will only say that I don't think this problem (strong security + performance) has been on the minds of very many people for very long, and this work is really still in its infancy.

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