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Re:A Survey on Homomorphic Encryption Schemes: Theory and Im... by whatidonteven on Wednesday September 06, 2017 @02:17PM (#15185859)
Aren't there MASSIVE (read: showstopper) complications when you want to use FHE for "looping" computations?

I always thought FHE was only good if you can fully unroll your "fixed-length" computation, and even then you can only use each "program" once without compromising security.

Re:A Survey on Homomorphic Encryption Schemes: Theory and Im... by swordswinger12 on Wednesday September 06, 2017 @07:15PM (#15187909)
The short answer is yes. There are some (slow) ways to fix this: https://people.csail.mit.edu/nickolai/papers/goldwasser-we.p...
Re:A Survey on Homomorphic Encryption Schemes: Theory and Im... by whatidonteven on Wednesday September 06, 2017 @08:43PM (#15188323)
Their construction relies on two unproven conjectures.

In particular the "Extractable Witness Encryption" conjecture is impossible under a reasonable falsifiable assumption: https://pdfs.semanticscholar.org/8587/dba4ff31e8118e9bd5914a...

Under that assumption, general purpose differing-inputs obfuscation cannot exist.

The way I understand it, FHE being applicable to anything other than "unwrapping a path through a circuit" seems implausible. Any claims of arbitrary encrypted computation should be viewed with the highest dose of skepticism.

Re:A Survey on Homomorphic Encryption Schemes: Theory and Im... by middleorigin on Wednesday September 06, 2017 @02:20PM (#15185894)
Hmm so it doesn't work well with variable length data?
Re:A Survey on Homomorphic Encryption Schemes: Theory and Im... by whatidonteven on Wednesday September 06, 2017 @02:24PM (#15185920)
You could say that.

Every time you want to run a computation on your FHE-enabled VPS you would need to upload data proportional to the maximum number of operations in the computation. Otherwise, re-running the same computation with a different input gives away information about both of your inputs and about the computation.