.

[Gavin Andresen]

why conflate the two issues?

Because to non-technical users, "privacy" is a single feature, not a series of separate technical issues.

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[marcus_of_augustus]

Does this patch give any sort of warning if bitcoin isn't being used through a proxy?

It raises the valid question whether the satoshi bitcoin client should actually have some kind of warning/button/icon to indicate that it isn't being used through a proxy.

(I mean checking in the Options... is not hard but all browsers now have the little padlock icon when a secure SSL connection is active ... for example.)

[figvam]

Could you also compile a 32-bit Linux binary?

[netrin]

why conflate the two issues?

Because to non-technical users, "privacy" is a single feature, not a series of separate technical issues.

Neither feature impacts nor increases the urgent need for the other and neither could claim to be the final "privacy" feature.

Could you also compile a 32-bit Linux binary?

I've failed to compile wxWidgets 2.9.2 and couldn't compile the patch with wxWidgets 2.8 on 32-bit Ubuntu 11.04  

[ctoon6]

Does this patch give any sort of warning if bitcoin isn't being used through a proxy?

I worry that a user will be REALLY careful keeping all their addresses separated so their ordinary transactions are separate from their fund-the-oppositition transactions, and then will get busted by the Secret Police who were eavesdropping on their bitcoin IP traffic at their ISP.

I see what you're saying although I don't think that's really a fair criticism of the patch.  Obtaining any really high level of anonymity is a very complex endeavor that no patch alone will get you.

This patch and a tor patch and an integrated laundering patch would just about cover it.

It may even be worthwhile to make a network almost exactly like tor, except only for bitcoin.

[Suggester]

That's just excellent work. I'm surprised it generated so little buzz and isn't adopted into the official client until now.

On a separate note, Suggester suggests a Redistribute coins button, an option which moves all your funds to a chosen number of new wallets with the desired proportion of your current coins assigned for each. A user would then be able to consolidate his wealth from all his, say, 17 addresses into just 3 new ones, with the first one containing 49% of his coins, the second one 26%, and the third 25% (he will be able to assign those %'s arbitrarily using a simple interface). Similarly, he might want to break up his single wallet into, say, 4 different wallets, using them for 4 different purposes. When the transactions clear after 10 minutes, it'll be harder for anyone to prove that this user still owns the coins previously associated with his identity.

For the suggestion to be practical for anonymity purposes though, I strongly recommend another adjustable option where the user chooses how much time to assign for the whole operation. For example, choosing "63.2 hours" would move random chunks of the coins into their new distribution over that period of time (the client would have to be connected for the whole duration). That would make plausible deniability much stronger because you usually don't have 17 people simultaneously sending all their coins to 3 new addresses! If done correctly, it will be virtually impossible after that for anyone to prove that he still owns the coins. We're essentially simulating a change-of-ownership.

This can all be currently done using windows explorer and separate wallet files, but it'll be a big pain in the butt.

[SgtSpike]

That's just excellent work. I'm surprised it generated so little buzz and isn't adopted into the official client until now.

On a separate note, Suggester suggests a Redistribute coins button, an option which moves all your funds to a chosen number of new wallets with the desired proportion of your current coins assigned for each. A user would then be able to consolidate his wealth from all his, say, 17 addresses into just 3 new ones, with the first one containing 49% of his coins, the second one 26%, and the third 25% (he will be able to assign those %'s arbitrarily using a simple interface). Similarly, he might want to break up his single wallet into, say, 4 different wallets, using them for 4 different purposes. When the transactions clear after 10 minutes, it'll be harder for anyone to prove that this user still owns the coins previously associated with his identity.

For the suggestion to be practical for anonymity purposes though, I strongly recommend another adjustable option where the user chooses how much time to assign for the whole operation. For example, choosing "63.2 hours" would move random chunks of the coins into their new distribution over that period of time (the client would have to be connected for the whole duration). That would make plausible deniability much stronger because you usually don't have 17 people simultaneously sending all their coins to 3 new addresses! If done correctly, it will be virtually impossible after that for anyone to prove that he still owns the coins. We're essentially simulating a change-of-ownership.

This can all be currently done using windows explorer and separate wallet files, but it'll be a big pain in the butt.

That would be a great feature of an online wallet website.  Just send funds with the parameters and addresses, and it'll all be done automatically by the site for a small fee.

[cjp]

I really need this patch! Is it available for version 0.4.0?

It doesn't seem to be in the standard client (0.4.0) yet. Why not? Sure, advertising it as an anonymity feature might give false expectations, but the same is true for the current client, since Bitcoin already has an anonymity reputation. This feature is not sufficient for complete anonymity, but it is a necessary (IMHO) component of a anonymous set-up, and as such it is a useful addition to the client. Sure, it adds complexity to the user interface (I haven't seen it yet), but this can easily be an 'optional' feature (and disabled by default), can't it?

Besides, I need it for a completely different reason: I want to manage several separated accounts, for an open source software development 'bounty' system (e.g., 'if you want to have this feature, send BTC to that address'). I want others to be able to see how much has been donated so far (or even how much they can receive if they implement the requested feature), so I don't want to accidentally spend bitcoins from the donation address.

[pointbiz]

I really need this patch! Is it available for version 0.4.0?

It doesn't seem to be in the standard client (0.4.0) yet. Why not? Sure, advertising it as an anonymity feature might give false expectations, but the same is true for the current client, since Bitcoin already has an anonymity reputation. This feature is not sufficient for complete anonymity, but it is a necessary (IMHO) component of a anonymous set-up, and as such it is a useful addition to the client. Sure, it adds complexity to the user interface (I haven't seen it yet), but this can easily be an 'optional' feature (and disabled by default), can't it?

Besides, I need it for a completely different reason: I want to manage several separated accounts, for an open source software development 'bounty' system (e.g., 'if you want to have this feature, send BTC to that address'). I want others to be able to see how much has been donated so far (or even how much they can receive if they implement the requested feature), so I don't want to accidentally spend bitcoins from the donation address.

It's possible https://www.bitaddress.org  could be useful for you to create separate accounts which you won't accidentally spend.

[btc_artist]

TLDR: this patch allows you to:
- see all addresses, including change
- see which addresses are linked together (does recursive expansion of address linkages)
- select which address(es) to send from, rather than letting the client to chose for you

Very nice. I hadn't seen this before now.

why conflate the two issues?

Because to non-technical users, "privacy" is a single feature, not a series of separate technical issues.

You have an excellent point about how non-technical users view privacy.  But you have to take a series of small steps to achieve a larger goal.  In privacy mode, Google Chrome lists several ways your privacy could still be compromised, yet that didn't keep them from adding privacy mode.  This patch should be added to the official client, but will obviously not be the last privacy-related improvement to bitcoin.

I updated the code for 0.4 but never released builds since I didn't perceive any demand for them.  The code is now updated for the 0.5 qt gui so once 0.5 is officially released I'll release builds with my patch as well.

Awesome.  I'll patch 0.5 when I start using it.

[cjp]

It's possible https://www.bitaddress.org  could be useful for you to create separate accounts which you won't accidentally spend.

Thanks for the suggestion. Isn't it true that I can do the same with some Linux scripts? I think I've read something like that in another thread. I'd prefer that approach, since I don't really trust arbitrary websites. It might secretly remember the private keys of the generated addresses and its operators might decide to cash out as soon as a certain amount of money is stored on addresses generated by them.

Anyway, I think this still requires a patch in my Bitcoin client, so that I can later import the private key.

I updated the code for 0.4 but never released builds since I didn't perceive any demand for them.  The code is now updated for the 0.5 qt gui so once 0.5 is officially released I'll release builds with my patch as well.

I don't need builds; please give me an URL for the source code of the version 0.4 patch. I'll give your code a quick security review (so hopefully it won't be too large) and then I'll compile my own client.

[btc_artist]

I'd prefer that approach, since I don't really trust arbitrary websites. It might secretly remember the private keys of the generated addresses and its operators might decide to cash out as soon as a certain amount of money is stored on addresses generated by them.

bitaddress.org is designed so that you can download the HTML/JS file(s) and run them on an offline machine.  It's all done in Javascript client-side and nothing goes to the server.

[netrin]

I don't need builds; please give me an URL for the source code of the version 0.4 patch. I'll give your code a quick security review (so hopefully it won't be too large) and then I'll compile my own client.

From the OP:

My github bitcoin fork: https://github.com/coderrr/bitcoin/tree/v0.3.24%2Bcoderrr
The commits with the changes: https://github.com/coderrr/bitcoin/commit/74411bec8438431e92a1ad0fd78495f3d742473d https://github.com/coderrr/bitcoin/commit/9376bcbaf7796f7fcf5e7f9976d3d42917507c63

[luv2drnkbr]

Thank you!

[0ni0ns]

Any chance of a windows build of 0.5 with the patch?

[phelix]

Any chance of a windows build of 0.5 with the patch?

+1

[SgtSpike]

Any chance of a windows build of 0.5 with the patch?

+1

+2

[finway]

That's where needs really are.

[mintymark]

I have to say that having read this, I am very disappointed. The anonymity available in bitcoin comes done to this: with special tools, a specialist will be able to violate the anonymity of anyone using the standard client. Shouldn't this be fixed at the protocol level? Perhaps by exchange of bitcoin amounts with random clients, these transactions might disguise legitimate transactions breaking the chain of address dependency.  This is not 'what it says on the box'!

Its true that eves-dropping is an issue, but its another issue, and in particular it requires action beforehand, while the blockchain is a permanent record, so can be analysed years afterwards to prove that I was sending money to more than one hot_lady!  (or whatever!)

Eves-dropping is an issue, but its not a reason for lack of action on this issue, Gavin, how could you imply such a thing? It sounds like an excuse for inaction.

While I really applaud the work of coderr and the Bitcoin authors, anonymity is a part of Bitcoins promise, this post makes it clear to me that for now at least, the past blockchain can be forensically analysed to reveal far more information than a casual user would expect. We need to see how we can deliver on this promise.

[SgtSpike]

I have to say that having read this, I am very disappointed. The anonymity available in bitcoin comes done to this: with special tools, a specialist will be able to violate the anonymity of anyone using the standard client. Shouldn't this be fixed at the protocol level? Perhaps by exchange of bitcoin amounts with random clients, these transactions might disguise legitimate transactions breaking the chain of address dependency.  This is not 'what it says on the box'!

Its true that eves-dropping is an issue, but its another issue, and in particular it requires action beforehand, while the blockchain is a permanent record, so can be analysed years afterwards to prove that I was sending money to more than one hot_lady!  (or whatever!)

Eves-dropping is an issue, but its not a reason for lack of action on this issue, Gavin, how could you imply such a thing? It sounds like an excuse for inaction.

While I really applaud the work of coderr and the Bitcoin authors, anonymity is a part of Bitcoins promise, this post makes it clear to me that for now at least, the past blockchain can be forensically analysed to reveal far more information than a casual user would expect. We need to see how we can deliver on this promise.

The bottom line is, Bitcoin should have never been advertised as being anonymous, because it simply isn't true.  At least, not with the default client.