The original idea was one where all transactions are conducted over a website only accessible via Tor. This part has been viable for years - it's always the money part that makes it risky for both the seller and the buyer.
The parts involving mail and double-sending drugs are ways to make the business scale, and make it work globally. They give plausible deniability to those receiving drugs.
I see lots of comments in this thread that "it would never work" and "the feds will come after you", but nothing detailing a specific way that they would detect who was mailing the drugs or running the business. The closest anyone came was Babylon, who suggested that the police might stake out all mailboxes in the area the packages came from, but that 's easily diffused: Locating the business in New York City, with 100k(?) public mailboxes would do the trick, or using common packaging like business envelopes.
(And to those that don't understand the concept of a thought experiment: No, I'm not actually planning to start a heroin store.)
Bullshit.Contrary to bitcoins, which are virtual and are only information bits, It is quite easy to track any physical evidence.
There are millions of possible methods using which any "heroin store" or other drug store can be tracked.
Let me just point out a few which came to my mind just now. This is surely only tiny part of what FBI/CIA/Whatever can use to track down location of the drug store.
1. Analysing paper type used in packaging the packages - where it was bought, where was it produced. It can probably narrow down the search to s section of country (state or land).
2. Analysing different residues that exist in the paper due to its previous location. Such residues may include :
- Dust from special type of soil existing only in certain territory
- Pollens from certain types of plants that exist only in a certain area, or have greatest concentration in certain area
- Humidity of the paper -can help narrow the search if the drug store is near water or far from water
- Chemicals in the paper (can narrow the search if drug store is located in a city/district with chemical plant, certain type of city etc)
3. Analyse organic residues from the person doing packaging & their DNA
4. Analyse the drugs themselves - repeat everything you have done with paper to the drugs & more.
Just the few methods above will probably be enough to narrow down the search to a small district of a city, or just few blocks... If not, then probably some additional, beter methods exist.
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Of course i realise that if you would be extremely, (or actually:
INSANELY) careful, pack all stuff underwater to avoid polluting, buy your paper in another country, work in latex gloves all the time, use mailboxes in a different random city each time etc, then perhaps you could successfully stay anonymous for few years or something... But
sooner or later you will make a mistake, because that's how human brain works. It always makes some number of mistakes, doesn't matter how hard you try.
And when you make the one fatal mistake, FBI/CIA/CSI will get you.