Let's give an example of bitcoinfog de-anonimization:
1DiYwzdc + wJdVzooF1H8h1h6 + wW4EV16PTjn is an Agora deposit address.
It receives 3 transactions from a tumbler on 17 nov 2014:
It's pretty obvious that the money is received from a tumbler, it doesn't make sense to send 3 deposits of those sizes to a darknetmarket on the same day.
This means that the actual deposit was 1,70324005 BTC.
Next step: Since in this example it's bitcoinfog and we know they have a 1-3% randomized fee we know that the minimum amount deposited into bitcoinfog is 1,7204 BTC(1% fee) and the maximum amount is 1,7559 BTC(3% fee). We also know that nearly all darknetmarket users think tumblers are holy and trust them blindly so they don't think to randomize deposits as well.
Next step: we look for bitcoin transactions between 1,7204 and 1,7559 within let's say 6 hours before the first transaction to 1DiYwzdc, we end up with a list of addresses that received between those amounts of btc.
Next: We take that list and use any method we have available to determine who those addresses belong to, some addresses belong to miners, some to exchanges, some to whoever else. One address raises our attention, 1QEA95T + rb6H1kn9guPy + 354M3X + wrCdvNhdX, look at the transactions....wait.......BINGO. We found the bitcoinfog deposit address.
1.7343 BTC was sent to 1QEA95T in this transaction. If you look at the originating address you see it's a change address for it's previous transaction, follow those and you end up at this transaction.
The sending addresses are operated by Localbitcoins. We now know the buyer bought his coins through LBC, if he used proper OPSEC(tor+anonymous buying method) he is probably safe. If not, LE knows who he is, imagine if he used circle or coinbase..
Repeat after me: Bitcoin is not anonymous, stop trusting anonymous services that promise you anonimity. The tumblers know their shit doesn't work, why would they care if they get 1-3% off every transaction that goes through them though? I can't even blame them for trying(and succeeding).
Inb4 Gramsadmin shows up and offers a bullshit explanation on how Grams is the ish, walletexplorer is not the only way certain services can be identified, Helix used predictable patterns in the past, Bitcoinfog used standard 13,88 BTC addresses to pay out withdrawals from in the past. Even if you randomize deposits and randomize withdrawals from tumblers you can not be safe from a method similar to this, for example if the market is compromised you could just as well have deposited into a single address.
The ONLY way tumblers can be effective is if they manually process each tumbling of coins, this is humanly not possible. Even then you are still trusting them not to be LE. This method doesn't prove anything 100%, but if the IRS can subpoena Facebook for 100s of user details and only get a 2% conviction rate you can bet your ass that the FBI can subpoena services based on the information they get from methods like these.
Finally, this is deanonimyzing tumblers from OUT to IN, the other way around is equally feasible, just slightly harder as you are now looking for an address that received between (deposit x 0.97) and (deposit x 0.99) BTC in let's say 1 to 4 transactions within about 6 hours. I am just too lazy to do try that the moment.
I am just a bored guy, imagine the tools LE has.
come on guys, learn to use Monero
and learn the best practices for using Monero. (use Mixin 3 or higher, know when to re-anonymize your transaction, such as when an exchange sends you a transaction with Mixin 0, 1 or 2)
Your transactions can be unlinkable in 2015.
Use www.mymonero.com for a software GUI.
Neither DARKWALLET or DARKCOIN's darksend/masternode technology, nor BITCOINDARK's telepathy nor SHADOWCOIN's technology will work as well as some good old fashioned stealthed ring signatures.
you will have to demand your markets upgrade too. Although Monero has been around for a while, it's software infrastructure is only just improving enough to be usuable. So things like multisig are still work in progress.