https://bitcointalk.org/index.php?topic=509144.msg5636651#msg5636651

Quote from: AnonyMint on March 11, 2014, 08:09:49 AM

Listen up please to learn some new technical information...

Quote from: Rampion on March 10, 2014, 12:35:51 PM

Quote from: domob on March 10, 2014, 11:35:38 AM

Got any good suggestions for trustless and low-fee mixers? I think all the P2P mixer projects are not yet fully ready, as far as I know.

...

Tumblers like bitcoinfog provide better obfuscation, but the (huge) trade-off is that you should trust an unknown third party. I'd never risk more than 1% of my holdings to such services, but I think the service they provide is necessary and should be used, albeit with care and with just a very minor portion of ones funds at a time.

Problem is there is no way to know if a centralized service (VPN, exchange, mixer, tumbler, laundry) is hacked, under NSA gag order, dishonest, buggy, etc..

Also using the centralized (VPN, mixer, tumbler, laundry) identifies you as someone that deserves extra monitoring by the authorities.

A decentralized solution is always best, as it should look like regular transactions.

Quote from: dserrano5 on March 10, 2014, 01:21:53 PM

Quote from: domob on March 10, 2014, 12:55:34 PM

Yes, I think CoinJoin should be a very good start. But do any really decentralised and fully working implementations of CoinJoin exist already? I don't think so and would be interested to know if they are.

I'm not aware of any either but don't let that deter you from using one of the already existing solutions even if they aren't perfect.

A decentralized CoinJoin will have difficulty forming transactions (including unequal or equal transaction amounts) that look like this if anyone can join:

https://blockchain.info/tx/e4abb15310348edc606e597effc81697bfce4b6de7598347f17c2befd4febf3b?show_adv=true

Quote from: piuk on November 18, 2013, 04:28:16 PM

A sharedcoin transaction will look something like this: https://blockchain.info/tx/e4abb15310348edc606e597effc81697bfce4b6de7598347f17c2befd4febf3b (picked at random). As you can see multiple inputs and outputs make the determining the actual sender and receiver more difficult.

The server does not need to keep any logs and transactions are only kept in memory for a short time. However If the server was compromised or under subpoena it could be force...

Because the way it must work is the users sign the transaction first with their requested outputs, then in the second round they sign their payments as inputs to the transaction. If the payment inputs are less than the total, then the transaction is invalid. There is no way to determine who cheated and rate limit them. Thus the saboteur can stomp on every attempt to create a CoinJoin transaction and destroy the decentralized system.

DarkCoin says they can solve this by charging a fee, but you will see I originally proposed that idea in the CoinJoin thread and the requirement is all the participants must be permanently identified and then must use divide-and-conquer to whittle down to who was the saboteur. But identification defeats the mixing!

Thus I have not yet seen a workable decentralized CoinJoin that can scale. And I don't expect one.

I posted this to the CoinJoin thread to get their technical peer-review of my statement.

Quote from: Gabi on March 10, 2014, 02:30:00 PM

Now, if the zerocoin concept would be implemented in bitcoin, it would be cool.

Just forget zerocoin even in an altcoin it won't work. Because it requires a trusted person to hold the private key that can unlock everything including taking all the zerocoins. This can't be fixed (contrary to ruminations otherwise), it is a fundamental mathematical property of the way zero knowledge proofs work when combined with an accumulator.

Also zerocoin has to be dedicated to preset transactions amounts (e.g. 1 BTC) else the anonymity set can be trivially collapsed by comparing input and output transaction amounts.

Quote from: phillipsjk on March 10, 2014, 04:09:44 PM

Quote from: gollum on March 10, 2014, 02:09:21 PM

Never recommend noobs to use Tor, it's a honeypot where they are worse off than not using Tor at all.
Noobs should use a trustworthy VPN instead.
The optimal solution is VPN + Tor.

Not if you stay in-network. Unfortunately, my services (bitcoin node) are not tor-enabled yet. Namecoin has the potential to facilitate this with human-readable addresses as well.

Not true. Tor is always subject to timing analysis by an entity such as the NSA (which is recording ans storing nearly all global encrypted traffic in Utah) which can see the encrypted packets running between Tor nodes.

Popular VPNs are also very likely all honeypots and unpopular ones give only a small anonymity set.

Currently the only known way to be reliably anonymous is use a connection to the internet that can't be traced to you, e.g. netcafe without cameras any where and don't drive your car as that has secret tracking built-in according to CEO of Ford, a throw-away mobile device and simm that doesn't have your id registered and used for no other activity, etc.

Quote from: AnonyMint on March 11, 2014, 09:39:41 AM

Quote from: Rampion on March 11, 2014, 09:31:38 AM

Anonymint: we are not discussing being safe against a global adversary such as the NSA, we all know that mixers + Tor is probably not enough to defeat them because of honeypots, timing attacks, deep packet inspection, etc...

We are discussing using basic security procedures in order not to be "the low hanging fruit" and thus being reasonably safe against the casual hacker/criminal doing trivial blockchain and network analysis to easily link identities to BTC balances. For that purpose running your wallet through Tor and using a decentralized and trustless mixer such as coinjoin should be enough.

The government and the criminals are sometimes one in the same.

But (uninformed) trust is all that is holding up the $150 trillion in fractional reserves, so you won't find too many people that subscribe to my view (yet). They will learn by 2020.

And you did not address my technical point about CoinJoin, which has nothing to do with the NSA.

In short, we are pretty well f8cked approaching the 2016ish global conflagrapocalpyse.

Adam Back (the creator of Hashcash which Bitcoin is based on) explains the anonymity problem (jump to 24:25 mins into the video).