daira

7 ms·

1.
by daira 7y ago
> BLAKE3 appears to have 128 bits of security against all attacks. That's not accurate. The best pseudo-preimage attack on BLAKE2s has complexity 2^{253.8} against 6.75 rounds (section 3.2 of https://eprint.iacr.org/
2.
by daira 8y ago
There's a pretty detailed proposal of a privacy-preserving L2 solution for Zcash, called BOLT ( https://z.cash/blog/bolt-private-payment-channels/ ). The original paper is at https://eprint.iacr.org&
3.
by daira 9y ago
Disabling SharedArrayBuffer is just stopping the most obvious method of exploitation; it's by no means a fix. Expect a slew of papers over the next few years on other methods of exploitation from JS.
4.
by daira 9y ago
But you don't detect that one case where you are actually compromised. You dismiss it like you do all the false positives. At best, when you get pwned you think back to having dismissed the key change warning and know what happened,
5.
by daira 9y ago
The legacy codebase issue we are lamenting there is just that the code inherited from Bitcoin is in C++. It's of course possible to interface between C++ and Rust, and that's what we're intending to do in future. It would hav
6.
by daira 9y ago
As far as I know we've never claimed that the distribution is flat or that the "effective anonymity" is equivalent to a uniform distribution over prior notes (I certainly didn't claim that). One of the advantages of Zcas
7.
by daira 9y ago
Note that the number of prior shielded transactions (not the proportion, and not the value) is what is actually relevant to the privacy of new shielded transactions. Roughly speaking, the privacy you get with Zcash is comparable to what you
8.
by daira 10y ago
This bug had nothing to do with Zcash. Please correct your comment to say Zcoin, if that's what you meant. In any case, Zcash is also derived from Bitcoin and builds with `-Werror` (edit: not `-Wall`, but we're working on that). T
9.
by daira 10y ago
Zcash, for example, is built with `-Werror` (edit: not `-Wall`, but we're working on that). So this is absolutely feasible on a Bitcoin-derived codebase.
10.
by daira 10y ago
No, that is not the bug. See Ian Miers' comments.
11.
by daira 10y ago
I'm not aware of any proof that Borromean signatures, relied on by CT, are secure assuming only ECDLP. There is certainly no such proof in the paper https://github.com/Blockstream/borromean_paper/blob/mas
12.
by daira 10y ago
This isn't a subtle or difficult-to-find case. It's a case of "why the heck would anyone write code like that, in any language, in the first place?" The only language-level abstraction needed to avoid this particular kin
13.
by daira 10y ago
Just to clarify, the code that was duplicated per denomination is not part of libzerocoin itself, it's in main.cpp. I'm not sure who wrote it; it may or may not have been part of the academic prototype Ian refers to. In any case,
14.
by daira 10y ago
The crypto used in Confidential Transactions, or any implementation of it, does not only rely on ECDLP. There's plenty of scope for potential protocol or implementation errors. (The Zcoin issue, remember, is an implementation error.)
15.
by daira 10y ago
There are ways to significantly reduce the cost of zk proof verification by batching (that are compatible with the existing Zcash protocol without a fork).
16.
by daira 10y ago
Fixed in Zcash 1.0.3. (They were always "working", despite the bugs that were recently fixed. You can see plenty of successful z-address transactions on the blockchain.)
17.
by daira 10y ago
The concern in that last sentence seems misplaced; there is no relation between proportion of monetary base held by an attacker, and proportion of mining power held by an attacker.
18.
by daira 10y ago
Basically yes. Strictly speaking privacy also relies on assumptions about Curve25519 (with a Blake2b-based key derivation function) and ChaCha20, but those are standard and uncontroversial.
19.
by daira 10y ago
It's a bit more complicated than that. The main responsibility for implementing connection layer unlinkability lies with Tor (if you use Zcash over Tor, which we will aim to provide good support for), but how effective that is in resis
20.
by daira 10y ago
Of course they've had to pay. In the case of the investors, they've had to pay cash up-front to fund the development of Zcash. In the case of other shareholders of Zerocoin Electric Coin Company, they've had to pay for, or ot
21.
by daira 12y ago
I don't actually see any assertions on this thread by natdempk or tptacek claiming that TextSecure is "trustworthy" and/or "solid". Did I miss something? My own opinion is that both strong cryptographic and sec
22.
by daira 12y ago
The scopes had a great deal of overlap; although we (Least Authority) didn't consider the iOS client at all, the rest of iSec's audit has essentially the same scope as ours. The point I was trying to highlight is how easy it is to
23.
by daira 12y ago
Actually I strongly suggest reading these in conjunction with iSec's issues 12 through 16, because each team spotted some details that the other missed.
24.
by daira 12y ago
Findings iSEC-RFACC0114-1 and iSEC-RFACC0114-3. (2 out of the 17 vulnerabilities found by iSec, of varying severity.)
25.
by daira 12y ago
This issue (or one with very similar effect) was also found by the Least Authority audit: https://github.com/cryptocat/cryptocat/issues/607 (The 'issue E' that it references is https://gi
26.
by daira 13y ago
I was one of the auditors for Least Authority. Just wanted to add that this audit was really fun to do! If you have the necessary experience and are part of a good team, security auditing is a fantastic job. -- Daira Hopwood