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Swift Homomorphic Encryption

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Re: Swift Homomorphic Encryption

#91

Post by hansvm »

nmadden wrote: post #54
hansvm wrote: post #53

Earlier quoted context omitted.

You can't attain IND-CCA2 (adaptively choosing cyphertexts based on previous decryptions). You can attain IND-CCA1 (after a decryption oracle, you're done fiddling with the system).

Right, but IND-CCA1 is kind of a toy security goal though. A sort theoretical consolation prize if you can’t achieve the real thing. And AFAICT, no actually implemented schemes do obtain even CCA1?

Sure, but that's "how much security you're sacrificing to get the FHE goodness," and, as always in crypto systems, implementations might not be that good.

> A sort theoretical consolation prize if you can’t achieve the real thing

The real thing exists largely because it makes proofs easier. For something like FHE you can bolt on some extra user-space features to build something like IND-vCCA (your decryption oracle refuses to operate if the result was not obtained by executing the right algorithm on the right ciphertext), which may or may not make FHE suitable for this or that target application. It's not a weak property though.

Re: Swift Homomorphic Encryption

#92

Post by yalogin »

FHE is cool but I wonder how many use cases it actually fits. Don’t get me wrong, it gives better security guarantees for the end user but do they really care if the organization makes a promise about a secure execution environment in the cloud?

Also from an engineering point of view, using FHE requires a refactoring of flows and an inflexible commitment to all processing downstream. Without laws mandating it, do organizations have enough motivation to do that?

Re: Swift Homomorphic Encryption

#93

Post by 77pt77 »

tombert wrote: post #28

I wrote some basic homomorphic encryption code for a hackathon like 8 years ago. When I interviewed for a BigTechCo [1] about a year later, the topic came up, and when I tried explaining what homomorphic encryption was to one of the interviewers, he told me that I misunderstood, because it was "impossible" to update encrypted data without decrypting it. I politely tried saying "actually no, that's what makes homomorp…

> he told me that I misunderstood, because it was "impossible" to update encrypted data without decrypting it. I politely tried saying "actually no, that's what makes homomorphic encryption super cool", and we went back and forth; eventually I kind of gave up because I was trying to make a good impression.

The moment you have to explain yourself you've already lost.

No argument you make will change their mind.

They are just stupid and that will never change.

And never forget, these people have power over you.

Re: Swift Homomorphic Encryption

#94

Post by [deleted] »

tombert wrote: post #28

I wrote some basic homomorphic encryption code for a hackathon like 8 years ago. When I interviewed for a BigTechCo [1] about a year later, the topic came up, and when I tried explaining what homomorphic encryption was to one of the interviewers, he told me that I misunderstood, because it was "impossible" to update encrypted data without decrypting it. I politely tried saying "actually no, that's what makes homomorp…

[deleted]

Re: Swift Homomorphic Encryption

#95

Post by nightpool »

yalogin wrote: post #92

FHE is cool but I wonder how many use cases it actually fits. Don’t get me wrong, it gives better security guarantees for the end user but do they really care if the organization makes a promise about a secure execution environment in the cloud? Also from an engineering point of view, using FHE requires a refactoring of flows and an inflexible commitment to all processing downstream. Without laws mandating it, do org…

> but do they really care if the organization makes a promise about a secure execution environment in the cloud?

Uh... demonstrably yes? No "secure execution environment" is secure against a government wiretap order. FHE is.

Re: Swift Homomorphic Encryption

#96

Post by nightpool »

bluedevilzn wrote: post #2

This must be the first real world use case of HE. It has generally been considered too slow to do anything useful but this is an excellent use case.

Second: Google Recaptcha Enterprise can use Homomorphic Encryption to check whether your password has been compromised (searching the set of all breached passwords without disclosing which individual password you want to check)

Now, in practice, HaveIBeenPwned does the exact same thing with a k-anonymity scheme based off of MD5 collisions, which is wayyyy easier in practice and what most people actually deploy, but the Google thing is cool too.

Re: Swift Homomorphic Encryption

#97

Post by nightpool »

Groxx wrote: post #24
dagmx wrote: post #20

Earlier quoted context omitted.

I believe Safari does the same as well, so not even technically the first at Apple if I’m correct?

After reading the technical details... I'm really not sure tbh: https://support.apple.com/guide/security/password-monitoring... I'm sure someone here understands that and can answer conclusively, but that's not me today.

No, the Apple article says that they're using the much faster and easier to implement k-anonymity strategy

Re: Swift Homomorphic Encryption

#99

Post by innermatrix »

kmeisthax wrote: post #26
MBCook wrote: post #12

Earlier quoted context omitted.

I tried to look homomorphic encryption up casually earlier this year. I saw references that it was being used, but I don’t think they said where. This is one topic I have a very hard time with, I just don’t know enough math to really grok it. It just seems crazy a system could operate on encrypted data (which is effectively random noise from the server’s point of view) and return a result that is correctly calculated…

Let's say I want you to add two numbers, but I don't want you to know what those numbers are, nor what the result is. What I can do is multiply both numbers by some other number you don't know. I then give you the premultiplied numbers, you add them, and give back a premultiplied answer. I can then divide out the number to get the true result. What we've done here is this: (a * key) + (b * key) = (c * key) The rules…

Finite fields have multiplicative inverse only if the base is a prime, and that's what makes the rest of your usual algebra work (or not).

For example, for N = 5, 0 * 2 = 2, 1 * 2 = 2, 2 * 2 = 4, 3 * 2 = 1, 4 * 2 = 3, so the inverse of "* 2" is uniquely defined. On the other hand, for N = 4, 0 * 2 = 0, 1 * 2 = 2, 2 * 2 = 4, 3 * 2 = 2, so the inverse of "* 2" is not uniquely defined.

Re: Swift Homomorphic Encryption

#100

Post by bobbylarrybobby »

yalogin wrote: post #92

FHE is cool but I wonder how many use cases it actually fits. Don’t get me wrong, it gives better security guarantees for the end user but do they really care if the organization makes a promise about a secure execution environment in the cloud? Also from an engineering point of view, using FHE requires a refactoring of flows and an inflexible commitment to all processing downstream. Without laws mandating it, do org…

I assume companies like it because it lets them compute on servers they don't trust. The corollary is they don't need to secure HE servers as much because any data the servers lose isn't valuable. And the corollary to that is that companies can have much more flexible compute infra, sending HE requests to arbitrary machines instead of only those that are known to be highly secure.
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