What NC State achieved is cool, but it seems a bit like saying "Homomorphic encryption is broken when you can blackmail the sysadmin."
I’m off to read this paper S I don’t understand how they are using a side channel to extract information that the operating device theoretically shouldn’t have. If there’s a measurable power usage difference over the operations that implies that the encrypted bits do leak information about what is encrypted.
This attack is on machine A, not machine B. The "leak" happens as the data is being encrypted. They're sidechanneling a machine that has the plaintext on it.
>Our proposed attack targets the Gaussian sampling in the SEAL’s encryption phase
It's literally about stealing the data from the encryptor, which is usually a trusted machine.
There's no reason rowhammer should be able to break homomorphic encryption. Homomorphic encryption means at no point is the data on the machine unencrypted, so there is nothing to leak from RAM.
>Homomorphic encryption is really about the utility when it leaves the device, not at the encryption stage.
???
This make no sense. Homomorphic encryption is used for a device to do computations on encrypted data without the device knowing what the encrypted data is.
For example, computing the square of an integer that is homorphically encrypted would not tell the device doing the computation what the original number is or what the square is. Encrypted data comes in, stays encrypted at all times, an algorithm does some operations on the encrypted data, and encrypted data is then sent out.
This paper and attack are not about the encryption stage. The attack is on the operating on homomorphic data.