Frequently Asked Questions

Who are you?

We are Jorge Martinez Pizarro, a Spanish mathematician turned professional programmer, and Stefan Richter, a German theoretical computer scientist who learned to appreciate programming through bitcoin and Scala.

What is this about?

When you use bitcoin today, you have to give away bitcoin addresses to people. That is, you announce "I have control over this address" to your business partners or even the whole world. The structure of the public blockchain often makes it possible for anyone to group multiple addresses as belonging to the same entity or person. This means that anybody who listened to your announcement and can perform this analysis gains knowledge like "you own at least x bitcoins" or "I know these addresses belong to you and I can now watch for your use of them".

Such analysis techniques have been known for a long time, but until now, mostly researchers have been able to actually process the huge amounts of data in the blockchain this way. However, interested parties have always been free to invest into evaluating this data. Arguably, criminals or government agencies might be parties interested in such knowledge. Bitcoinprivacy.net puts this power back in the hands of every bitcoin user.

What exactly can you tell me?

Probably the simplest analysis is repeatedly grouping addresses that appear together as inputs in the same transaction. There are other heuristics, but this is what you can find out with our tool from the beginning. So when you enter a bitcoin address, we can tell you what other addresses have been used in the same payments as this one, and what balances they contain. So when you pay someone, you can now tell what the recipient learns about you with respect to bitcoins you own.

Is it reliable?

This particular heuristic is very reliable. It proves that the people who own a group of private keys had to work together in order to spend bitcoins. However, there are two caveats:

  • 1. This does not mean that one person actually owns all these bitcoins. A counterexample might be an address belonging to an exchange or wallet provider. This entity controls bitcoins given to them by their customers.
  • 2. CoinJoin is a proposal for a group of techniques that lets multiple people join their transactions together to make it look like one person spent all these bitcoins, in order to thwart exactly the kind of analysis we are performing. If everyone used CoinJoin, the naive implementation that we are using now would be useless. If you have used a CoinJoin implementation on your addresses, the results from our search can not be trusted anymore. Your addresses are effectively mixed with those of other people. But beware: There is research that makes it possible to unmix joined coins. It is just a little more work. We plan on implementing these ideas later on.

How can I protect my privacy?

Following the general suggestion of never reusing addresses is a very good idea. It does not prevent you from linking addresses, but the moment that they are linked they are also spent; so the public learns nothing about your bitcoin balance. Unfortunately, many wallets (web wallets in particular) make this simple measure hard or even impossible. 

Mike Hearn has written about ways of actually avoiding merging addresses. Unfortunately, we are not aware of any tools implementing this, so it remains a manual process.

How does this work?

We built the open source Bitcoin Graph Explorer to do the heavy lifting. Feel free to fork and explore!

How can I help?

Glad you asked. Processing and storing gigabytes upon gigabytes of blockchain data doesn't come for free. If you find this helpful, we are grateful for your donation: 1L1EnvmZ8Gg42NTzGwEHrMD4XaosmgntKF If you are a developer, feel free to contribute to our our open source projects on github. Writing tests would be a great start, because we never seem to get around to that.

How can I reach you?

We'd love to read your feedback: info@bitcoinprivacy.net .

 

Are you GDPR compliant?

We are a private non-commercial website and don't store personal data of any kind. So I guess we are. If you think otherwise, send us an email!