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Zerocoin: making Bitcoin anonymous

blog.cryptographyengineering.com

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Re: Zerocoin: making Bitcoin anonymous

#61

Post by jlgreco »

brianberns wrote: post #55
vessenes wrote: post #45

I like seeing proposals like this that use Bitcoin as essentially a protocol layer (and in this case value store). 40KB anything is not going anywhere near the blockchain soon; this is going to be a no-go for the dev team and miners. There are also a bunch of ancillary questions, like can these zero knowledge proofs (presumably non-interactive ones) be combined up with the rest of the blockchain to be turing-complete…

I know what Turing-complete means, but can you explain how the blockchain could become Turing-complete, and why that would be a bad thing?

I'm not sure how it would happen, but if you could get miners to perform arbitrary computation for you, as a consequence of processing zerocoin transactions, then people might decide to abuse that and generate tons of otherwise unnecessary transactions.

Re: Zerocoin: making Bitcoin anonymous

#62

Post by IanCal »

johndevor wrote: post #20
mdelias wrote: post #17

Earlier quoted context omitted.

Since BTC is expected to be regulated like a currency Citation? The recent FinCEN statement [1] does not support your claim. [1] http://fincen.gov/statutes_regs/guidance/html/FIN-2013-G001....

However, an administrator or exchanger is an MSB under FinCEN's regulations Would they not try to claim that using Zerocoin is, in effect, making you an independent exchange? Or are you only an exchanger when going from Bitcoin to USD? An exchanger is a person engaged as a business in the exchange of virtual currency for real currency, funds, or other virtual currency. There is this clause, but it only refers to busi…

"Would they not try to claim that using Zerocoin is, in effect, making you an independent exchange?"

Might be difficult, there's no market there. One Zerocoin is one Bitcoin in value by definition. It's not an exchange to convert dollars into cents, so it would be hard to argue this.

Re: Zerocoin: making Bitcoin anonymous

#63

Post by dragontamer »

johndevor wrote: post #20
mdelias wrote: post #17

Earlier quoted context omitted.

Since BTC is expected to be regulated like a currency Citation? The recent FinCEN statement [1] does not support your claim. [1] http://fincen.gov/statutes_regs/guidance/html/FIN-2013-G001....

However, an administrator or exchanger is an MSB under FinCEN's regulations Would they not try to claim that using Zerocoin is, in effect, making you an independent exchange? Or are you only an exchanger when going from Bitcoin to USD? An exchanger is a person engaged as a business in the exchange of virtual currency for real currency, funds, or other virtual currency. There is this clause, but it only refers to busi…

I'm more interested in: "An administrator is a person engaged as a business in issuing (putting into circulation) a virtual currency, and who has the authority to redeem (to withdraw from circulation) such virtual currency."

If you participate in the Zerocoin network, you can therefore issue Zerocoins (in exchange of bitcoins), and redeem Zerocoins for bitcoins.

Re: Zerocoin: making Bitcoin anonymous

#64

Post by dragontamer »

jasonlingx wrote: post #30
dragontamer wrote: post #8

Since BTC is expected to be regulated like a currency, wouldn't participating in Zerocoin be basically money laundering? If that is the case, participating in the Zerocoin network itself would be a crime. I don't think this is going to go anywhere. And if it does, then hope that the Secret Service doesn't catch you even touching this stuff...

> Since BTC is expected to be regulated like a currency Huh? I thought it's the opposite?

If you live in America, you are subject to American Law. If you don't follow the law, you get put in jail.

Its like any other law, except the Secret Service is especially hard on money launderers.

Re: Zerocoin: making Bitcoin anonymous

#65

Post by dragontamer »

jasonlingx wrote: post #30
dragontamer wrote: post #8

Since BTC is expected to be regulated like a currency, wouldn't participating in Zerocoin be basically money laundering? If that is the case, participating in the Zerocoin network itself would be a crime. I don't think this is going to go anywhere. And if it does, then hope that the Secret Service doesn't catch you even touching this stuff...

> Since BTC is expected to be regulated like a currency Huh? I thought it's the opposite?

If you live in America, you are subject to American law, regardless of the technicalities of the technologies you employ. You are expected to follow the law and the spirit of the law.

Re: Zerocoin: making Bitcoin anonymous

#66

Post by TazeTSchnitzel »

rb2k_ wrote: post #58

Another option would be to just use an existing mixing service: https://en.bitcoin.it/wiki/Mixing_service Those services always reminded me of David Chaum's Mix Networks: http://en.wikipedia.org/wiki/Mix_network )

They're the same as the "laundering" services the article mentions.

Re: Zerocoin: making Bitcoin anonymous

#68

Post by w-ll »

limmeau wrote: post #59
w-ll wrote: post #52

Earlier quoted context omitted.

What stops me from 'minting' zerocoins by selling them to myself? exchanged with gold? what?

When you Mint a zerocoin, you spend a BTC. When you redeem a zerocoin, you receive a BTC. The collective of miners verifies that you don't get rich doing so.

But how do you know I just dont "sell it" to a btc address I already own? Or maybe I dont understand what you mean by spend BTC? Paid to who? The person "minting" coins, which is not a POW system?

Re: Zerocoin: making Bitcoin anonymous

#69

Post by limmeau »

w-ll wrote: post #68
limmeau wrote: post #59

Earlier quoted context omitted.

When you Mint a zerocoin, you spend a BTC. When you redeem a zerocoin, you receive a BTC. The collective of miners verifies that you don't get rich doing so.

But how do you know I just dont "sell it" to a btc address I already own? Or maybe I dont understand what you mean by spend BTC? Paid to who? The person "minting" coins, which is not a POW system?

The Mint transaction, which becomes part of the block chain, establishes consent that the given bitcoin address owns one BTC less and that simultaneously the given Zerocoin becomes valid.

Minting takes place within the block chain, unlike Dollar exchanges on MtGox, which are not directly visible as such in the block chain.

Re: Zerocoin: making Bitcoin anonymous

#70

Post by Flenser »

davmre wrote: post #53
yk wrote: post #39

Earlier quoted context omitted.

As far as I understand the posting, this depends on the total minted Zerocoins. Since you can not tell with any certainty that a specific Zerocoin is already redeemed ( except if all are redeemed, more on that later), the probability that a specific Zerocoin belongs to you is 1/n, where n is the number of addresses which have ever generated Zerocoins. However, there are some assumptions in the argument, most importan…

> the probability that a specific Zerocoin belongs to you is 1/n I think you're missing the subtlety that the parent was trying to get at. Imagine that everyone redeemed their Zerocoins exactly five minutes after minting them; it'd be trivial to match up which coin was being redeemed. Now obviously that'd be stupid, so instead let's say you choose when to redeem your Zerocoin randomly, by sampling a waiting time from…

I don't understand how once the zero coin's serial number is revealed in the spend transaction it can remain anonymous. Can't you then go back and test previous mint transaction to see if it was for that serial number? If you're doing it continuously, so you keep a record of which mint transactions you know have been spent it would reduce the workload.
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