3 ms·

Isn't zero-knowledge a subset of end-to-end (where both ends are you)

by homakov 10y ago

Canada 10y ago
No, it's not.
- homakov 10y ago
  Well, who decides what it is? When security words go marketing, it's pointless to argue. Zero knowledge is yet another "military grade" buzzword.
  - Canada 10y ago
    You're right that marketing can sometimes make what was once black into white, but that doesn't make it true. A phrase like "military grade" is now and was always a meaningless, nonsense phrase used to suggest robustness. No military has actually defined any "grade" of encryption to measure with. It's like saying that your ladies deodorant is "Strong Enough For a Man". Sure, whatever. End to end encryption (E2E) on the other hand means something specific: The secrets critical to the security of the system live on the end user devices. If a standard webmail service claims to be E2E, it's not marketing, it's lying. Likewise, zero knowledge has a well defined meaning. It's a protocol where a Prover convinces a Verifier that it has some information, without actually revealing what that information is. For example, Peggy could have a set of public keys, whose order she has randomly shuffled. She can prove to Victor that the output of her Shuffle is a valid permutation of the keys, without revealing to Victor what order they were in before she shuffled them. Zero knowledge protocols are useful building blocks for such tasks as: - Mixing messages in a way that prevents a global passive adversary who also maliciously runs some of the routers in a network from learning the social graph of users (Tor cannot do this, because it is not zero knowledge) - Verifiable secret ballots. Voting systems where you receive proof that your ballot was cast as you intended, but you can't use the proof to convince anyone else. (To mitigate vote buying/voter intimidation) - Offering a database where users can query information, but the database operators cannot know what records have been requested If a product doesn't provide such features, or doesn't make use of a zero knowledge proof, then calling it zero knowledge is nothing more than a brazen lie.
    - homakov 10y ago
      The secrets critical to the security of the system live on the end user devices: Ok so my desktop is device #1, and mobile is #2. I encrypt a note on desktop, then "query information, but the database operators cannot know what records have been requested" with device #2, it seems this concept fits to end-to-end definition you gave? I really think both terms are so vague that can be bended in a way that they look interchangeable. And nothing wrong about it.
      - hvidgaard 10y ago
        They are two very different things. E2E is a term that dictates that when I send information, only the intented reciepient can decrypt it, under the assumption that the keys are safe. Zero knowledge proofs is a constuct where I can prove something to you, without leaking any information. For instance, you want to buy a house, but before the seller wants to sign, he wants proof that you can actually pay x $ in down payment. Traditionally you would go down to your bank, get a piece of paper stating that you have x $ locked and only usable for this purchage for the next 60 days. It doesn't say how much you have in your account, where the money is from or anything else. A zero knowledge proof is the same, just digital. E2E would not help here, because it doesn't prove anything, it's just a term about the comunication being safe.
        homakov 10y ago
        I know what you mean, ZK as in password auth. Then why in the first place encrypted storage was called zero knowledge? Complete misuse of the term.
        hvidgaard 10y ago
        Not really. My example could just as well be done with any public key crypto system. If you want better examples, see the SO post https://mathoverflow.net/questions/22624/example-of-a-good-zero-knowledge-proof https://mathoverflow.net/questions/22624/example-of-a-good-z... But misuse of the term is most likely just because they didn't understand it in the first place. It is well defined, but rather abstract.

Isn't zero-knowledge a subset of end-to-end (where both ends are you)

by homakov 10y ago

Isn't zero-knowledge a subset of end-to-end (where both ends are you)

Canada 10y ago

No, it's not.

homakov 10y ago
Well, who decides what it is? When security words go marketing, it's pointless to argue. Zero knowledge is yet another "military grade" buzzword.
- Canada 10y ago
  You're right that marketing can sometimes make what was once black into white, but that doesn't make it true. A phrase like "military grade" is now and was always a meaningless, nonsense phrase used to suggest robustness. No military has actually defined any "grade" of encryption to measure with. It's like saying that your ladies deodorant is "Strong Enough For a Man". Sure, whatever. End to end encryption (E2E) on the other hand means something specific: The secrets critical to the security of the system live on the end user devices. If a standard webmail service claims to be E2E, it's not marketing, it's lying. Likewise, zero knowledge has a well defined meaning. It's a protocol where a Prover convinces a Verifier that it has some information, without actually revealing what that information is. For example, Peggy could have a set of public keys, whose order she has randomly shuffled. She can prove to Victor that the output of her Shuffle is a valid permutation of the keys, without revealing to Victor what order they were in before she shuffled them. Zero knowledge protocols are useful building blocks for such tasks as: - Mixing messages in a way that prevents a global passive adversary who also maliciously runs some of the routers in a network from learning the social graph of users (Tor cannot do this, because it is not zero knowledge) - Verifiable secret ballots. Voting systems where you receive proof that your ballot was cast as you intended, but you can't use the proof to convince anyone else. (To mitigate vote buying/voter intimidation) - Offering a database where users can query information, but the database operators cannot know what records have been requested If a product doesn't provide such features, or doesn't make use of a zero knowledge proof, then calling it zero knowledge is nothing more than a brazen lie.
  - homakov 10y ago
    The secrets critical to the security of the system live on the end user devices: Ok so my desktop is device #1, and mobile is #2. I encrypt a note on desktop, then "query information, but the database operators cannot know what records have been requested" with device #2, it seems this concept fits to end-to-end definition you gave? I really think both terms are so vague that can be bended in a way that they look interchangeable. And nothing wrong about it.
    - hvidgaard 10y ago
      They are two very different things. E2E is a term that dictates that when I send information, only the intented reciepient can decrypt it, under the assumption that the keys are safe. Zero knowledge proofs is a constuct where I can prove something to you, without leaking any information. For instance, you want to buy a house, but before the seller wants to sign, he wants proof that you can actually pay x $ in down payment. Traditionally you would go down to your bank, get a piece of paper stating that you have x $ locked and only usable for this purchage for the next 60 days. It doesn't say how much you have in your account, where the money is from or anything else. A zero knowledge proof is the same, just digital. E2E would not help here, because it doesn't prove anything, it's just a term about the comunication being safe.
      - homakov 10y ago
        I know what you mean, ZK as in password auth. Then why in the first place encrypted storage was called zero knowledge? Complete misuse of the term.
        hvidgaard 10y ago
        Not really. My example could just as well be done with any public key crypto system. If you want better examples, see the SO post https://mathoverflow.net/questions/22624/example-of-a-good-zero-knowledge-proof https://mathoverflow.net/questions/22624/example-of-a-good-z... But misuse of the term is most likely just because they didn't understand it in the first place. It is well defined, but rather abstract.