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Bitcoin Users Reveal More Private Information Than They Realize

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Re: Bitcoin Users Reveal More Private Information Than They Realize

#21

Post by Sinergy »

Taek wrote: post #19
Sinergy wrote: post #15

I hope everybody here knows about BitcoinFog, Shared Send, and other mixers. And uses them for random transactions now and then to give the rest of us plausible deniability.

Most mixers introduce points of centralization, which allow a party to steal your coins or allow them to break privacy. JoinMarket is a good solution that works on Bitcoin today. Monero is a good altcoin which will automatically mix your coins using crypto. I believe it is more powerful than JM but requires using an altcoin. Zcash offers unmatched anonymity powered by fancy new crypto (less tested, less certainty on…

Assuming you are careless enough to use only one mixer for a transaction, they form points of centralization.

Assuming no mixer reputation, they allow a party to steal your coins. Note that breaking a large transaction into small pieces allows you to determine a sort of short-term reputation while only risking one piece at a time.

My standard first two steps used to be SharedCoin->BitcoinFog, for example.

Re: Bitcoin Users Reveal More Private Information Than They Realize

#22

Post by ikeboy »

LAMike wrote: post #11

When SegWit is released in a few months, confidential transactions will be right around the corner

That only keeps the amount transferred private, not the addresses. Also, it has nothing to do with segwit, it was proposed well before segwit was a thing.

Re: Bitcoin Users Reveal More Private Information Than They Realize

#24

Post by feral »

This is a nice write-up.

That said, I hope this is less of a surprise to people now: I coauthored one of the first pieces of working pointing out basically these same issues back in 2011 - almost 5 years ago:

http://anonymity-in-bitcoin.blogspot.ie/2011/07/bitcoin-is-n...

It's interesting to see what perceptions have changed. That there's still confusion shows how hard it is to disseminate information about encryption and privacy; maybe this the same reason e2e email encryption seems so difficult to get adopted, even decades after PGP: it's just hard to communicate about the bounds of privacy.

One point: the 'clusterisation' mentioned in the linked article isn't 'magic': most of the techniques people are using are actually very simple heuristics, based on properties of the Bitcoin protocol (transaction input linking, which we demonstrated), or assumptions about transaction 'change' (prone to false positives).

It's worth noting that there are more sophisticated tools that could be applied: machine learning or stats methods - but I've not seen them yet. Possibly because its hard to come up with good training datasets (unless you are a retainer or wallet?) and not worth investing in when simple methods show so much. But its worth bearing in mind that more complex analysis is possible.

The overall conclusion being, IMO, that if you want privacy, it's probably usually easier to design it in from the start, rather than retrofit by progressively patching holes in a leaky system, against progressively better attacks: the latter is so hard to get to the point where it works solidly: for human reasons as much as technical ones; I think Bitcoin privacy seems destined to be an example of this.

Re: Bitcoin Users Reveal More Private Information Than They Realize

#25

Post by natrius »

Money is a claim on value, and fungibility forces everyone to honor all claims on value. An incorruptible record of the flow of trade through an economy allows you to eliminate fungibility. You can withdraw your consent for people to trade claims on your production. This ability requires no one's permission and makes you more powerful as an individual.

ISIS, for instance, can only hold territory because everyone accepts the claims on value that they give their foot soldiers. I want to stop honoring those claims to reduce their power. Manufacturers shift their carbon emissions to friendly jurisdictions instead of, you know, not risking our only home for cheap consumer goods. They do this to acquire more claims on value, and I don't want to honor those claims because I like Earth.

Fungibility is literally killing people and destroying our planet. I think we'll be better off without it, though as with all significant social shifts, it probably needs more study to avoid unforeseen consequences like genocides and stuff. Blockchains are not anonymous—their incorruptible histories give us the tools to reshape our society. Use them.

Re: Bitcoin Users Reveal More Private Information Than They Realize

#26

Post by moeadham »

NobleSir wrote: post #2

Shameless plug for Monero https://eprint.iacr.org/2015/1098.pdf (ring ct author here) edit: See also https://github.com/shennoether/ringct and https://github.com/monero-project/bitmonero

Monero definitely deserves more credit that it is currently given.

Re: Bitcoin Users Reveal More Private Information Than They Realize

#27

Post by gnaritas »

Sinergy wrote: post #15

I hope everybody here knows about BitcoinFog, Shared Send, and other mixers. And uses them for random transactions now and then to give the rest of us plausible deniability.

> Mixers

A PC name for money launderers. If you need a money launderer, you should rethink what you're doing.

Re: Bitcoin Users Reveal More Private Information Than They Realize

#28

Post by ultramancool »

eru wrote: post #23
ultramancool wrote: post #3

What's next? Well, true anonymity via zero knowledge proofs of course. https://z.cash/

What about https://en.wikipedia.org/wiki/Zerocoin inside bitcoin?

Zcash is what zerocoin has become (same developers). The hopes of getting something like this into bitcoin... may still be possible, but would require agreement amongst miners and developers. Something that seems unlikely right now.

The separate altcoin is the smartest way to experiment with it for now at least.

Re: Bitcoin Users Reveal More Private Information Than They Realize

#29

Post by AgentME »

gnaritas wrote: post #27
Sinergy wrote: post #15

I hope everybody here knows about BitcoinFog, Shared Send, and other mixers. And uses them for random transactions now and then to give the rest of us plausible deniability.

> Mixers A PC name for money launderers. If you need a money launderer, you should rethink what you're doing.

They're not necessarily about hiding from the law. They can be used to get any privacy from the general public. All bitcoin transactions are publicly broadcast to everyone. Do you use a shower curtain specifically for hiding from the government?

Re: Bitcoin Users Reveal More Private Information Than They Realize

#30

Post by miscellaneous »

gnaritas wrote: post #27
Sinergy wrote: post #15

I hope everybody here knows about BitcoinFog, Shared Send, and other mixers. And uses them for random transactions now and then to give the rest of us plausible deniability.

> Mixers A PC name for money launderers. If you need a money launderer, you should rethink what you're doing.

Noun, 1. money laundering: Concealing the source of illegally gotten money.

Do you have any evidence that suggests that all users of mixers obtained their Bitcoin illegally?

This HN post is a criticism of the privacy of Bitcoin transactions. Mixers can improve the privacy of Bitcoin transactions. I don't see how your comment adds to this discussion, unless you think financial privacy is a crime - in which case your statement applies equally to cash transactions.

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