5 ms·

2^80 is not very weak. That's the level of brute forcing a SHA-1 collision. It's low for a new system, but not very weak. I agree with your 20%/10% comments, b

2^80 is not very weak. That's the level of brute forcing a SHA-1 collision. It's low for a new system, but not very weak. I agree with your 20%/10% comments, but I do not know why you call ZCash an investment. Zcash should discourage people from investing, like Monero does. Be a privacy coin, do not try to get in on the moon and lambo hypetrains if you want to be taken seriously. There is no good justification for 20% right now. ZEC market cap is half a billion today. Do they really need that extra 50 mln now versus over time? Feels greedy. But with so much taken by them that way, does that not reduce their desire to get a backdoor? At any rate, all of this ceremony and your measures seem, as you say, hocus pocus if you're not building from known source! Forget hardware attacks! How can they not have the basics of a secure toolchain?!? Did some participants at least publish the source they used and hashes of the toolchain and environment? At my startup (details in profile) we will end up depending on crypto (among other things) to stay out of prison. Monero is hard to use, privacy wise - EABE and EWE attacks are our concerns. At least with ZCash the model is fairly easy to understand with shielded transactions. Much easier than figuring out ringsize and traceability there. But the Monero community seems better with no 20% take, no central company, none of this trusted nonsense. And no odd comments by both founders that require lots of mental gymnastics to make sense of. Not that any of this should matter. ZCash should be trusted on its own merits regardless of the inventors. Monero has anonymous inventors which could be the NSA for all we know. Alas I am in no position to analyze ZCash math vs RingCT but my feeling is the latter is more understandable and thus might be more secure even if it has much weaker safety promises.

ewillbefull 9y ago
> 2^80 is not very weak. That's the level of brute forcing a SHA-1 collision. It's low for a new system, but not very weak. Note that the 2^80 figure from Peter's blog post is really unsubstantiated. There's another curve in libsnark (which we don't use) that has 80-bits of security. I suspect what happened is whoever Peter was consulting with just repeated this number to him. We've spoken to many cryptographers who are experts on these curves, and none of them think that figure is reasonable. I actually don't believe there are _any_ cryptographers that have publicly made such a claim about the security. 2^96 was the original conservative estimate when the NFS attack was discovered, but subsequent analysis showed concrete security closer to 2^110 (and that's ignoring the unrealistic memory costs of the specific attack.) > How can they not have the basics of a secure toolchain?!? We provided participants with a reproducibly built and stripped down version of Alpine Linux, employed grsec, wrote all of our crypto software in pure Rust, etc. All of our software is reproducibly built, hashed and signed. There is nothing (software-wise) that cannot be caught in post-hoc review. All of it is open-source: https://github.com/zcash/mpc https://github.com/zcash/mpc Several academic papers regarding our protocol have been published since then. We wrote a full security proof of the crypto. We hired NCC group to audit the ceremony as well: https://z.cash/blog/ceremony-audit-results.html https://z.cash/blog/ceremony-audit-results.html More auditing can always be done but this is a continuing process. The primary goal is to make it difficult for someone to undetectably compromise the ceremony.
- the_stc 9y ago
  What is Peter referring to when he says there's no reproducible builds?
  - petertodd 9y ago
    I didn't say that. What I said was those builds hadn't been properly audited; just being reproducible isn't enough unless people actually reproduce them, and additionally, audit the dependencies that go into those builds.
- petertodd 9y ago
  What my blog actually said about that was: "I’ve had some experts tell me they thought the security level was 2^80 operations (very weak), while others (including Zooko himself) thought it was [more like 2^96](https://moderncrypto.org/mail-archive/curves/2016/000742.html https://moderncrypto.org/mail-archive/curves/2016/000742.htm...). I’m not sure which figure is right, but the fact that there’s disagreement is a bad sign." I made it very clear that it is an unsubstantiated figure, and linked to Zooko's analysis. To both yourself and the person you're replying too, please don't put words in my mouth. > We provided participants with a reproducibly built and stripped down version of Alpine Linux, employed grsec, wrote all of our crypto software in pure Rust, etc. All of our software is reproducibly built, hashed and signed. There is nothing (software-wise) that cannot be caught in post-hoc review. All of it is open-source: https://github.com/zcash/mpc https://github.com/zcash/mpc I agree. But that's not what I said; what I said is that post-hoc review hasn't been done, even a year after the fact.
  - ewillbefull 9y ago
    > To both yourself and the person you're replying too, please don't put words in my mouth. What words did I put in your mouth? I cited the 2^80 figure in your blog post and a reasonable theory for why you would bring up such a figure. "Regurgitated" came across as snide so I apologize for that. Note that you used this unsubstantiated figure to say "the fact that there’s disagreement is a bad sign." If there isn't actually any disagreement and the figure is unsubstantiated, why is it not baseless FUD? (BTW I notified you of this error in your blog post some time ago but never heard back.) > what I said is that post-hoc review hasn't been done, even a year after the fact. I know, I wasn't replying to you. As I said, I believe more auditing is needed. I also don't believe some kind of one-and-done audit of the software/deterministic builds would satisfy either of us.
petertodd 9y ago
> Alas I am in no position to analyze ZCash math vs RingCT but my feeling is the latter is more understandable and thus might be more secure even if it has much weaker safety promises. Depends on what type of security you want. If you're talking about security against inflation, then RingCT is definitely safer than Zcash. But if you're talking about privacy security, then Zcash is more secure than RingCT; the trusted setup can only be used to create fake Zcash, not deanonymize transactions.
- kobeya 9y ago
  Well it’s a free choice. You can make non look math systems that have unconditional privacy instead of unconditional inflation guarantees.
  - kobeya 9y ago
    *non moon-math
- RandVal30142 9y ago
  >the trusted setup can only be used to create fake Zcash, not deanonymize transactions. "I think we can successfully make Zcash too traceable for criminals like WannaCry, but still completely private & fungible" "I _don't_ mean weakening security (https://z.cash/support/faq.html#backdoor https://z.cash/support/faq.html#backdoor …). I mean that a secure protocol layer is compatible with good law enforcement." -zooko Not sure how your statements carry water in the face of that comment.

ewillbefull 9y ago

> 2^80 is not very weak. That's the level of brute forcing a SHA-1 collision. It's low for a new system, but not very weak. Note that the 2^80 figure from Peter's blog post is really unsubstantiated. There's another curve in libsnark (which we don't use) that has 80-bits of security. I suspect what happened is whoever Peter was consulting with just repeated this number to him. We've spoken to many cryptographers who are experts on these curves, and none of them think that figure is reasonable. I actually don't believe there are _any_ cryptographers that have publicly made such a claim about the security. 2^96 was the original conservative estimate when the NFS attack was discovered, but subsequent analysis showed concrete security closer to 2^110 (and that's ignoring the unrealistic memory costs of the specific attack.) > How can they not have the basics of a secure toolchain?!? We provided participants with a reproducibly built and stripped down version of Alpine Linux, employed grsec, wrote all of our crypto software in pure Rust, etc. All of our software is reproducibly built, hashed and signed. There is nothing (software-wise) that cannot be caught in post-hoc review. All of it is open-source: https://github.com/zcash/mpc https://github.com/zcash/mpc Several academic papers regarding our protocol have been published since then. We wrote a full security proof of the crypto. We hired NCC group to audit the ceremony as well: https://z.cash/blog/ceremony-audit-results.html https://z.cash/blog/ceremony-audit-results.html More auditing can always be done but this is a continuing process. The primary goal is to make it difficult for someone to undetectably compromise the ceremony.

the_stc 9y ago
What is Peter referring to when he says there's no reproducible builds?
- petertodd 9y ago
  I didn't say that. What I said was those builds hadn't been properly audited; just being reproducible isn't enough unless people actually reproduce them, and additionally, audit the dependencies that go into those builds.
petertodd 9y ago
What my blog actually said about that was: "I’ve had some experts tell me they thought the security level was 2^80 operations (very weak), while others (including Zooko himself) thought it was [more like 2^96](https://moderncrypto.org/mail-archive/curves/2016/000742.html https://moderncrypto.org/mail-archive/curves/2016/000742.htm...). I’m not sure which figure is right, but the fact that there’s disagreement is a bad sign." I made it very clear that it is an unsubstantiated figure, and linked to Zooko's analysis. To both yourself and the person you're replying too, please don't put words in my mouth. > We provided participants with a reproducibly built and stripped down version of Alpine Linux, employed grsec, wrote all of our crypto software in pure Rust, etc. All of our software is reproducibly built, hashed and signed. There is nothing (software-wise) that cannot be caught in post-hoc review. All of it is open-source: https://github.com/zcash/mpc https://github.com/zcash/mpc I agree. But that's not what I said; what I said is that post-hoc review hasn't been done, even a year after the fact.
- ewillbefull 9y ago
  > To both yourself and the person you're replying too, please don't put words in my mouth. What words did I put in your mouth? I cited the 2^80 figure in your blog post and a reasonable theory for why you would bring up such a figure. "Regurgitated" came across as snide so I apologize for that. Note that you used this unsubstantiated figure to say "the fact that there’s disagreement is a bad sign." If there isn't actually any disagreement and the figure is unsubstantiated, why is it not baseless FUD? (BTW I notified you of this error in your blog post some time ago but never heard back.) > what I said is that post-hoc review hasn't been done, even a year after the fact. I know, I wasn't replying to you. As I said, I believe more auditing is needed. I also don't believe some kind of one-and-done audit of the software/deterministic builds would satisfy either of us.

petertodd 9y ago

> Alas I am in no position to analyze ZCash math vs RingCT but my feeling is the latter is more understandable and thus might be more secure even if it has much weaker safety promises. Depends on what type of security you want. If you're talking about security against inflation, then RingCT is definitely safer than Zcash. But if you're talking about privacy security, then Zcash is more secure than RingCT; the trusted setup can only be used to create fake Zcash, not deanonymize transactions.

kobeya 9y ago
Well it’s a free choice. You can make non look math systems that have unconditional privacy instead of unconditional inflation guarantees.
- kobeya 9y ago
  *non moon-math
RandVal30142 9y ago
>the trusted setup can only be used to create fake Zcash, not deanonymize transactions. "I think we can successfully make Zcash too traceable for criminals like WannaCry, but still completely private & fungible" "I _don't_ mean weakening security (https://z.cash/support/faq.html#backdoor https://z.cash/support/faq.html#backdoor …). I mean that a secure protocol layer is compatible with good law enforcement." -zooko Not sure how your statements carry water in the face of that comment.