I guess they could identify you only once you cashed out. Other than that, your identity is safe (unless you have verified your identify in an online wallet, of course);
WRONG. For but one of a hundred other ways your identities could be linked, even if you mix with CoinJoin, check out this pretty picture from a research paper I referenced in my earlier post on this thread:
Stop giving dangerously bad advice!
What I was always wondering about was how those mixing services work? Do they just send the transaction that you want to send to eg 10000 different addresses before sending it to the destination address? So it would be a huge amount of work to check all the addresses? I cant imagine how else they could make a transaction non trackable on Bitcoins blockchain. But this would also not be doable because of the transaction cost and speed. Maybe someone can explain it to me?
You ask some reasonable questions. More reasonable still would be the question of how to actually protect your privacy. That last is a difficult question. Strong anonymity (or more properly, the transaction unlinkability required for strong privacy) requires considerable expertise; there does not currently exist any point-and-click solution which will make that happen for you.
Ive been trying to write up a little post on the basics; but it takes time, since unlike some people here, I dont simply toss out substance-free gab to hear myself talk. It is a complicated topic; and I know that if I give the wrong advice, people could get hurt. I may or may not finish what I was writing. Meanwhile, here are some notes:
I observe in brief that I have never used a Bitcoin mixer site. I am a privacy activist. I have exclusively connected to the Internet through Tor for some years nowjust on principle. Ive been intrigued by the potential of private digital currency since Chaumian Digicash was still a thing; that was a few decades ago. And I have never used a Bitcoin mixer site. That might suggest to you something about those Bitcoin mixers.
Some people here need to read this paragraph thrice, from the newbie-level introduction at https://bitcoin.org/en/you-need-to-know#anonymous (italics added):
Quote from: bitcoin.org
Bitcoin is not anonymous
Some effort is required to protect your privacy with Bitcoin. All Bitcoin transactions are stored publicly and permanently on the network, which means anyone can see the balance and transactions of any Bitcoin address. However, the identity of the user behind an address remains unknown until information is revealed during a purchase or in other circumstances. This is one reason why Bitcoin addresses should only be used once. Always remember that it is your responsibility to adopt good practices in order to protect your privacy. Read more about protecting your privacy.
Some effort is required to protect your privacy with Bitcoin. All Bitcoin transactions are stored publicly and permanently on the network, which means anyone can see the balance and transactions of any Bitcoin address. However, the identity of the user behind an address remains unknown until information is revealed during a purchase or in other circumstances. This is one reason why Bitcoin addresses should only be used once. Always remember that it is your responsibility to adopt good practices in order to protect your privacy. Read more about protecting your privacy.
The same people should also read that read more link very carefully.
Observe some discussion by smart people who know what they are talking about. (N.b. that I cant recommend CoinJoin or Joinmarket at this time unless you know its limitations, and you really know what you are doing. Look back to the above graphic. The little crossover icons in the left half represent CoinJoins.)
Finally, I must quote this for the right spirit. Privacy is not for criminals; it is to protect you from criminals:
I don't have much need for anonymity, but not having everyone from your nosy neighbors to random thieves knowing all your financial activity is both a matter of human dignity and basic safety.
There exist corrupt and oppressive governments. There also exist robbers, stalkers, identity thieves, and kidnappers who are increasingly sophisticated in their exploitation of digital information sources. I think it is only a matter of time before organized crime catches on in a big way to the goldmine of useful information which can be linked through blockchain tracing; perhaps they have already, and I just dont yet know it. All these threats can work retroactively, too. Every transaction you commit to the blockchain is there forever.
Dont be paranoid, but take precautions. I use Bitcoin for whatever I want to, nobody knows how much I have, and I sleep quietly at night. Of course, I dont engage in criminal activitythats outside my threat model. I just wantno, I demand privacy; and I have it, at the expense of some large effort. Its worthwhile!