Bitcoin Forum

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bitcoinbitcoin:
How anonymous are bitcoins?

Can nodes on the network tell from which and or to which bitcoin address coins are being sent? Do blocks contain a history of where bitcoins have been transfered to and from? Can nodes tell which bitcoin addresses belong to which IP addresses? Is there a command line option to enable the sock proxy the first time that bitcoin starts? What happens if you send bitcoins to an IP address that has multiple clients connected through network address translation (NAT)?

> Can nodes on the network tell from which and or to which bitcoin
> address coins are being sent? Do blocks contain a history of where
> bitcoins have been transfered to and from?

Bitcoins are sent to and from bitcoin addresses, which are essentially random numbers with no identifying information.

When you send to an IP address, the transaction is still written to a bitcoin address.  The IP address is only used to connect to the recipient's computer to request a fresh bitcoin address, give the transaction directly to the recipient and get a confirmation.

Blocks contain a history of the bitcoin addresses that a coin has been transferred to.  If the identities of the people using the bitcoin addresses are not known and each address is used only once, then this information only reveals that some unknown person transferred some amount to someone else.

The possibility to be anonymous or pseudonymous relies on you not revealing any identifying information about yourself in connection with the bitcoin addresses you use.  If you post your bitcoin address on the web, then you're associating that address and any transactions with it with the name you posted under.  If you posted under a handle that you haven't associated with your real identity, then you're still pseudonymous.

For greater privacy, it's best to use bitcoin addresses only once.  You can change addresses as often as you want using Options->Change Your Address.  Transfers by IP address automatically use a new bitcoin address each time.

> Can nodes tell which bitcoin addresses belong to which IP addresses?

No.

> Is there a command line option to enable the sock proxy the first
> time that bitcoin starts?

In the next release (version 0.2), the command line to run it through a proxy from the first time is:
bitcoin -proxy=127.0.0.1:9050

The problem for TOR is that the IRC server which Bitcoin uses to initially discover other nodes bans the TOR exit nodes, as all IRC servers do.  If you've already connected once before then you're already seeded, but for the first time, you'd need to provide the address of a node as such:
bitcoin -proxy=127.0.0.1:9050 -addnode=<someipaddress>

If someone running a node with a static IP address that can accept incoming connections could post their IP to use for -addnode, that would be great.

> What happens if you send bitcoins to an IP address that has multiple
> clients connected through network address translation (NAT)?

Whichever one you've set your NAT to forward port 8333 to will receive it.  If your router can change the port number when it forwards, you could allow more than one client to receive.  For instance, if port 8334 forwards to a computer's port 8333, then senders could send to "x.x.x.x:8334"

If your NAT can't translate port numbers, there currently isn't a command line option to change the incoming port that bitcoin binds to, but I'll look into it.

Why would you run bitcoin through Tor?  What is the security advantage?

I just realize that this is a very old post.

I wouldn't say running bitcoin through tor would be a security advantage, rather more of an anonymity advantage in that it would be almost impossible to link a transaction to your ip.

How might someone determine your IP address through bitcoin (assuming you are not sending using the IP address option)?  I'm just curious how Tor protects your anonymity beyond the protection offered by bitcoin.

Much easier said than done.    Most routine e-commerce transactions will link the bitcoin address with other identifying information, and determined attackers can overcome the privacy of even extremely careful bitcoin users:

(1) If you don't use Tor, the merchant (or whoever your payment counterparty might be) will have a log or cache entry linking your IP address to your bitcoin address.

(2) If you use Tor, but the end-to-end info is unencrypted, the Tor exit node can (and you should assume will) have a log or cache entry linking your bitcoin address, any identifying info you sent to the merchant, and the merchant.

(3) If you use Tor, but forget to or can't turn off web cookies, your bitcoin address can be linked to a web cookie, which in turn is often linked to your IP address by an advertising aggregator like Google/Doubleclick.

(4) If you order goods shipped to your address, the merchant will have a log or cache entry linking your name, snail-mail address, and any other identifying information you gave, even if you used Tor.

(5) Each bitcoin record links your bitcoin address with those of all the counterparties that address has transacted with.   Depending on the length and variety of the record it can reveal your shopping pattern which is often uniquely distinguishable from other shopping patterns, just as fingerprints or DNA are unique. 

(6) Determined investigators or a software system somebody might write (similar to advertiser's software used to track user preferences across merchants) can gather and integrate information from different bitcoin nodes, vendors, etc. the bitcoin user's software has communicated with.   Even if one log by itself doesn't tell much information, an aggregation of logs from several different merchants and transactions might speak volumes.

(7) etc., there are undoubtedly many other ways to link bitcoin addresses with other identifying information, caused by bitcoin itself, by outside entities the information-gathering and sharing nature of which most users will not be aware, or combinations thereof.

Secure anonymity on the Internet is pretty hard to do.

All the information gathering you mentioned above did not come from the bitcoin network.  You are referring to common browser and user security weaknesses.  Let's assume that a user is not revealing personal information on a channel outside of the bitcoin network.  Maybe they are using Tor (and turning off cookies).  Or maybe they place an ad in the newspaper with their bitcoin address.

What might someone be able to learn about this bitcoin address I saw in a recent newspaper classified ad: 1N9vKDweKCF9Yibapky7UmqRJ8PKgnvM2s

I'm fairly technical and I feel confident you cannot learn anything about the bitcoin client that is receiving bitcoins at that address.

http://blockexplorer.com/address/1N9vKDweKCF9Yibapky7UmqRJ8PKgnvM2s

I can not believe this reply is empty.
No mercy from those who get rich and get the advantage of being anonymous currency. AND GET RICH.
THANKS SATOSHI FOR WORKING BETTER FUTURE FOR HUMANITY.
and you didn't even touch billion dollars wallet.
thanks again

In fact, Bitcoin is probably the most transparent payment network in the world. At the same time, bitcoin can provide acceptable privacy if used properly. Always remember to develop good habits to protect your privacy is your own responsibility. And the biggest feature of bitcoin is not anonymity but the transfer of equal wealth with the fastest speed of transmission to the elimination of all kinds of ideologies in the world.

BTC is anonymous until you convert it into fiat.

In some countries it will be not anonymous anymore. However, it is still safer that fiat money. I love Bitcoins for this reason.

the principle of the blockchain is to be transparent, if we want anonymity must turn to the monero

you have a very brilliant thought that can be realized to be real where bitcoin is now really starting to be known throughout the world, Maybe the right call for you is einstein crypto

I hate to open up such an old thread, just found it odd to see Satoshi asking this question and then answering it himself, did he slip up and forget to use another account to post the question?
Are their any other accounts linked to Satoshi?

Can't you see the title? It's a repost of another user's question...

PS. I can't help but notice that all the replies from 2018 are hilariously bad except for the first one. The ICO spam era must have been worse than I thought.

What have you learned from what he wrote? Because if learning is all you care about you won't try to make the founder look like a spammer, that's his way of explaining more about Bitcoin and anonymity, if you don't or can't learn anything here just ignore.

Just something i found interesting. It gave you sig spammers something to post about  :D

The Op is not interested in what was written. He just want to prove that satoshi has alts.

Lolz, they are hilarious but I can't say that they are bad because there was no abundance of bitcoin knowledge then. Bitcoin was relatively new and as such people are expected not to have in-depth knowledge of it.

BTW: I thought all satoshi threads are locked, did theymos forget this one?

OP's would sling that NAT thing at me like it was a threat back in the days.

Cheers.

I thought they were all locked too, was surprised that i could post.
I was just reading a few old Satoshi posts for fun.
I also noticed that Satoshi profile is number 3, i wasnt really expecting it to be #1, who were the first 2 members here?

ha, yeah I remember those days... people would throw around 'NAT' like it was some magic word for being compromised. it's funny looking back because it was mostly just FUD from folks who didn't understand the network layer.

wasn't a threat, just a sign of who hadn't set up a node behind a firewall. the whole debate back then was about pseudo-anonymity vs real anonymity, which we're still arguing about now with coinjoin and cashfusion. the pattern is always the same: someone finds a potential weakness, it gets blown out of proportion for a cycle or two, then the actual tech slowly improves to fix it.
that NAT scare was just a precursor to the whole chain analysis panic we see today.

it's less about the tech and more about people's comfort level with being observed.