what went wrong: TLDR probably Ctrl-C,Ctrl-V. (Just to be clear, this is about Zcoin, not Zcash/Zerocash. The two are completely different) The fix is here. https://github.com/zcoinofficial/zcoin/commit/33796c839f7d4d... What happened? First, some stylized facts about ZCoin: 0) ZCoin is a fork of Bitcoin that uses a 4 year old academic research library, libzerocoin, to make anonymous payments using the Zerocoin proto…
Another major bug caused by copy+paste. I seem to remember a security researcher article months (years?) ago that identified this theme, showed a way to grep a codebase for likely c+p errors and found a load of bugs in real production code that had remained hidden for years. I think I landed there from HN, but my google-fu is failing me now, can anyone else remember it?
Zerocoin implementation bug
131–140 of 142 posts
Re: Zerocoin implementation bug
#132Earlier quoted context omitted.
"Someone steals my credit card, and if I notice within 2 months, I can get everything back." No. You may still be liable for $500 if you fail to report it within 48 HOURS: http://consumer.findlaw.com/credit-banking-finance/are-you-l... "Another advantage is that it doesn't take several hours" You hold a common misconception of how transactions work. Bitcoin transactions are transmitted/notified instantly (like credit…
that argument about bitcoin mining not being wasteful just shows it's not wasteful compared to other decentralized, trustless currencies. It still loses out to traditional payment methods. "It will only use 1% of the world's electricity consumption". We can only do that for 100 things. Does "decentralisation of currency" belong in the top 100 things to devote electricity generation to? EDIT: do you have a link to a f…
"Does "decentralisation of currency" belong in the top 100 things to devote electricity generation to?"
I think so. If (big if) Bitcoin ever becomes so successful that 1% of the energy is spent on it, think about the massive scale of positive social and economic changes it means it will have brought: freeing people from economic censorship and persecution, reducing international payment friction hence increasing economic trade, etc.
But I think neither you nor I can envision the scale of such potential social and economic changes. It is like asking a random person from the 1890s how much do they think automobiles will change the world, and almost nobody would have predicted automobiles are a major enabler of the economic expansion of the 20th century.
Transaction speeds: zero-conf txs are at risk of a double-spend, but in practice this happens extremely rarely.
Re: Zerocoin implementation bug
#133Earlier quoted context omitted.
I don't think the principle of money is actually that difficult. We've all had that moment in middle school where we realised that money would be worthless if everyone stopped caring about it. It's just that some people stopped running around wide-eyed telling others about this revelation a few days later. I guess we did get lucky in that the object of obsession they chose wasn't the law. Please don't tell them that…
> money would be worthless if everyone stopped caring about it. Sure, on the surface this is easy to understand. But what might it look like for such a process to unfold? How do the fundamental dynamics and primary characteristics of a money system change over time, and why? Honestly, I can't really answer those questions in any kind of sophisticated way. A lot of discussions involving the Fed and broad macroeconomic…
Re: Zerocoin implementation bug
#134Earlier quoted context omitted.
That's true, but if this was the epic exit scam they were planning for so many years, it's a bit disappointing.
410 BTC is half a million dollars.
Not saying it's impossible this is a scam, but I still doubt it.
Re: Zerocoin implementation bug
#135Earlier quoted context omitted.
Seems very unlikely since it would inevitably cause many to lose faith in the currency. If they really want to cash out, they can just do what almost every other upstart cryptocurrency founder does and make it clear they're taking some of the pie.
You're assuming the one who introduced the bug was a founder with the ability to do that.
Re: Zerocoin implementation bug
#136Earlier quoted context omitted.
This type of challenge is implicit in any cryptocurrency with strong confidentiality (i.e. which conceals the amount being transferred from public view) unless you trust the "inputs-equal-outputs" proving mechanism (which, in Zcash's case, is the zk-SNARK that accompanies a shielded transaction). One potential solution is to periodically require that all coins be unshielded (i.e. sent to a t-address) and passed throu…
What? This is totally incorrect. It is perfectly possible to build systems that verify total issuance while concealing amounts. Blockstream's Confidential Transactions does this, for example.
Obviously there are implementation risks, but in terms of cryptographic risk you are correct.
Re: Zerocoin implementation bug
#137Earlier quoted context omitted.
>No. You may still be liable for $500 if you fail to report it within 48 HOURS "may" is much different than "are". I've had it happen 3 different times and didn't realize until many days later and was never asked to pay for any of it. Guess how much you lose if someone steals $50,000 of bitcoin from you and you don't notice for 48 hours? >Transactions will be confirmed and spendable by the recipient within 10min on a…
""may" is much different than "are"" Which is why I corrected the poster who made it sound like credit cards "always" protect you, when it's not true. "Often" and "mostly", but not "always". "Guess how much you lose if someone steals $50,000 of bitcoins" Hardware wallets solve the theft problem. To date there have been no verifiable incidents of Bitcoins stolen from hardware wallets. Credit cards as they are implemen…
This is a distinction irrelevant in the real world where the status quo (at least in the US) is that companies protect you. Bitcoin has to compete with what exists, not a potential strawman based on what the laws say.
>Hardware wallets solve the theft problem. To date there have been no verifiable incidents of Bitcoins stolen from hardware wallets.
Can hardware wallets be stolen? If so, you just lost $50k regardless of the attacker gaining access to it. If not, it means you have keys backed up somewhere that can be stolen.
>>"Almost nobody gives two shits about how long it takes"
>Listen, I was just pointing out people who say "CCs transactions are quicker than Bitcoin transactions" are wrong.
Don't quote out of context. The rest of my sentence clearly shows I'm referring to the speed for the consumer. From a consumer perspective, the transaction is done right when the credit card machine returns (a.k.a within seconds).
>Accepting a zero-conf Bitcoin transaction is similar ("as risky as") accepting a CC transaction after swiping/chip-and-pin.
No it's not. A zero-conf transaction someone can double-spend against and the merchant has no recourse and the consumer has no risk. Merchants will be forced to wait for confirmation unless they have other leverage against the consumer to use on bad behavior.
In CC transactions, the risk to the merchant is a chargeback. A consumer can only lie about these a few times in their life before they get caught by a combination of the credit card company and a merchant and they will be arrested for credit card fraud.
Until the government steps in and writes laws making double-spending fraud, CC will be safe than zero-conf transactions.