Why bitcoin is not anonymous
Imagine that the person owns a purse Andthat has bitcoins. No one knows what a person is associated with this wallet. A person wants to transfer the bitcoins to your wallet Used on the exchange to exchange bitcoins for “real” money. The exchange knows the number of the card, which removes money from the purse B, and some exchanges even require a phone number or even a selfie with your passport.Transfer bitcoin anonymous wallet And to non-anonymous wallet B is public, accessible information. All transactions for all of the wallets stored in a database called the blockchain. It is inherent in the mechanics of bitcoin. You can watch transactions of any wallet blockchain.info.
You put it in a mixer with a bitcoin wallet And. It remembers how much you “should” and transfers your bitcoins to other users of the mixer, each on a small lot of money. On your wallet B it makes the translation of some of his purse, which gathered the required amount of bitcoins with other users. In the end blockchain.info it is seen that bitcoin wallet And went to dozens or hundreds of unrelated purses with you. The associated costs B bitcoins came from a purse belonging to the mixer. Thus the obvious connection between the wallet And a and B are no more.
The clustering method against the mixers
With the development of information technologies and the accumulation of an increasing number of statistical data appeared methods of processing large datasets (Big Data). One of them is the clustering method. The method in the probabilistic partitioning all the input data for certain subgroups defined criteria.
In simple words, you can collect all the information from the blockchain, and this is enough to link two of the purse, between which is a mixer. Basic criteria: when the transfer is made and the amount of transfer. In the mixer went 0.235 BTC and a couple of hours on a purse came 0.230 BTC. Analysing the blockchain, the program will mark these two as wallet associated with reliability close to 100%.
According to the cited on the Internet analytical data, 95% of the transactions through the mixers is decrypted successfully by the method of clustering.
Is it possible to counteract this
You can try to complicate the task of these spy analysts. For example, to introduce into the mixer the amount, break it into many translations in a dozen different wallets (addresses), and output them on the bitcoins slowly over a week or two. Some mixers provide such an interface.
This enough effective focus, there is no certainty.
The concern is that the mapping bitcoin addresses < mastodons engaged in the bitcoin industry, Bitfury and Chainalysis, and they work closely with the special services. A darknet businesses were deanonymization their analysts. They use not only the analysis of the blockchain, but all the information I can gather: public databases, social networks, data from the exchanges, "merge" information to customers, etc., Their resources are huge.
For serious cases it is necessary to Supplement or replace the mixers, other methods of anonymizing your bitcoins. For example, this is the transfer of bitcoins in the anonymous cryptocurrencies: zcash for, Monero or Dash. Their blockchain is not publicly available and, therefore, opportunities for deanonimizatsii much less.