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Swift Homomorphic Encryption

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Re: Swift Homomorphic Encryption

#31

Post by ReptileMan »

What is the processing that the server does on the encrypted phone number? I am not sure I understand. I always thought that this type of encryption was (roughly and imprecisely) - you send some encrypted blob to the server, it does some side effect free number crunching on the blob and returns the output blob. You decrypt the blob and everyone is happy.

But to return information if some number is spam it has to be either plaintext or hashed condition somewhere outside of the phone?

Re: Swift Homomorphic Encryption

#32

Post by nmadden »

The thing that I always want to know with FHE: the gold standard of modern encryption is IND-CCA security. FHE by definition cannot meet that standard (being able to change a ciphertext to have predictable effects on the plaintext is the definition of a chosen ciphertext attack). So how close do modern FHE schemes get? ie how much security am I sacrificing to get the FHE goodness?

Re: Swift Homomorphic Encryption

#34

Post by jancsika »

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…

Digression-- this is a good example where the mumbo jumbo that anarchists buzz on about applies in a very obvious way.

You were literate in that domain. The interviewer wasn't. In a conversation among equals you'd just continue talking until the interviewer yielded (or revealed their narcissism). The other interviewers would then stand educated. You see this process happen all the time on (healthy) FOSS mailing lists.

Instead, you had to weigh the benefit of sharing your knowledge against the risk of getting in a pissing contest with someone who had some unspecified (but real!) amount of power over your hiring.

That's the problem with a power imbalance, and it generally makes humans feel shitty. It's also insidious-- in this case you still don't know if the interviewer said "no" because they misunderstood homomorphic encryption.

Plus it's a BigTechCo, so we know they understand why freely sharing knowledge is important-- hell, if we didn't do it, nearly none of them would have a business model!

Re: Swift Homomorphic Encryption

#36

Post by MBCook »

colmmacc wrote: post #14
tedunangst wrote: post #11

Earlier quoted context omitted.

Okay, I figure if Apple wanted, they could simply query every number and see which disk blocks get read. But now maybe I'm confused. They read the whole database on every query?

My understanding of encrypted search in FHE is that there can be multiple copies of the same search key, and that search keys aren't simply in-place encrypted versions of themselves - as encrypted fields in a database are - but are mappings embedded in a higher dimensional space that is encrypted. That reads like sci-fi nonsense, but the "on the metal" result is that a search key will translate to a set of memory loc…

Do I have this right?

If the server could actually decode things it would’ve gotten something that could be decrypted into let’s say 15 phone numbers. A little bit like if they were hashed, to simplify.

So the answer the server returns isn’t who the phone number belongs to, it’s who those 15 phone numbers belong to.

And then the client can decrypt it and just get the one that it cares about.

But unlike if you were just doing hash buckets no one who saw the data going back-and-forth could actually understand any of it. Correct?

Is this only really good for data to look up cases? I had thought homomorphic encryption could be used to do actual calculations, at least certain kinds.

Re: Swift Homomorphic Encryption

#37

Post by ChadNauseam »

jancsika wrote: post #34
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…

Digression-- this is a good example where the mumbo jumbo that anarchists buzz on about applies in a very obvious way. You were literate in that domain. The interviewer wasn't. In a conversation among equals you'd just continue talking until the interviewer yielded (or revealed their narcissism). The other interviewers would then stand educated. You see this process happen all the time on (healthy) FOSS mailing lists…

In my experience this comes up a lot less often when people are paid to be empirically right, and the most annoying arguments occur when no one has an interest in being right and instead wants to defend their status. e.g. try telling a guy with his date nearby that he's wrong about something irrelevant like how state alcohol minimum markups work. An even more common scenario is when someone is passionate about a political topic and they publicly say something incorrect, and now would look like a fool if they admitted they were wrong. Sometimes I worry that a post-money future would become entirely dominated by status considerations and there would be no domain where people are actually incentivized to be right. Do you know if there's any anarchist thought related to this topic?

Re: Swift Homomorphic Encryption

#38

Post by MBCook »

tempay wrote: post #30
dllthomas wrote: post #27

Earlier quoted context omitted.

I don't see why it would? IIUC, the promise of homomorphic encryption is that I can encrypt my database of contacts and send it to an untrusted server, later send the encrypted query to that untrusted server, and get back an encrypted response, without the server being able to tell anything that couldn't be told from the wire (some bounds on how much data, timing of communication, that sort of thing) or provide an in…

That's not the use case mentioned here. The example given is blocking known spam callers and displaying identity information on the incoming call screen. To do this without homomorphic encryption requires the entire DB to be sent to every client. Even if size wasn't an issue (which it is), it's hard to update it frequently. Homomorphic encryption means you can ask Apple "who is calling me" without Apple knowing who i…

Not really. You could do it the way the Have I Been Pwned database works.

You hash your query and then send only the first X number of bits.

The server returns all results that hash up to that same first X number of bits.

The server doesn’t know exactly what number you were looking for, and you don’t have to download the entire database.

But in this case the server WOULD be able to figure out the set of possible phone numbers you were asking about. Because of the complexity of passwords the search space would be a lot larger.

So privacy wise this does seem better.

Re: Swift Homomorphic Encryption

#39

Post by lcnPylGDnU4H9OF »

jancsika wrote: post #34
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…

Digression-- this is a good example where the mumbo jumbo that anarchists buzz on about applies in a very obvious way. You were literate in that domain. The interviewer wasn't. In a conversation among equals you'd just continue talking until the interviewer yielded (or revealed their narcissism). The other interviewers would then stand educated. You see this process happen all the time on (healthy) FOSS mailing lists…

> the mumbo jumbo that anarchists buzz on about

I enjoy exposing myself to new-to-me opinions. Do you know a decent anarchist blog/vlog to dip my toes into this area?

Re: Swift Homomorphic Encryption

#40

Post by dboreham »

ReptileMan wrote: post #31

What is the processing that the server does on the encrypted phone number? I am not sure I understand. I always thought that this type of encryption was (roughly and imprecisely) - you send some encrypted blob to the server, it does some side effect free number crunching on the blob and returns the output blob. You decrypt the blob and everyone is happy. But to return information if some number is spam it has to be e…

The "side effect free number crunching" in this case is: is in

You're on the right track with the idea of hashing -- I find it helpful to explain any fancy encryption scheme beginning with "if it were just hashing", then extend to "well this is a very fancy kind of hash", and now I kind of understand what's going on. Or at least it's no longer magic.

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