It's a bit more nuanced isn't it (or am I mistaken)? All you see in the ledgers is the (hopefully single use) addresses the money is sent to, plus all addresses that come after it. There's not much in the system itself that links people / organisations to addresses, right? You'll have to get that information from outside the system: you know yourself, and maybe the receiver as a person, but where it then ends up requires you to obtain knowledge that's not readily available.

Sure there's a lot stored, which does bring privacy concerns that are quite different from our current financial system, I'm not debating that, but it's not as obvious as you put it, as far as I understood it.

"We've killed people based on metadata" - Former USA CIA director. [1]

It really isn't that nuanced at all for Bitcoin. If I know your wallet I can see all of your transactions. Period. And if you want to trade money with me, you need to give me your wallet. Once I find it, thought, it is game over. [2]

There are "tumblers" that attempt to obfuscate the chain by turning one transaction into millions of little ones, but it is just a matter of tree search to reconstruct.

[1] https://www.rt.com/usa/158460-cia-director-metadata-kill-peo...

[2] https://www.blockchain.com/explorer

The problem is that it's global and irrevocable: mistakes and intentional linkages act as a ratchet increasingly deanonymizing the network over time. If it started to have real usage, you'd quickly see the equivalent of the credit card / scoring companies, Google, etc. paying merchants for transaction details and building a web of user information.

Ooof. That is a great second-order observation: agencies profiling you and making lifer harder or easier based on your blockchain history. Not like this is new, as you point out, just even more difficult to expunge: there's no "blockchain" to expunge your blockchain habits! (yet??? I think I have a new startup idea for blockchain ... /bangsheadagainstwall/)

Sadly, these days my threat model for anything new is basically “how will Google/Facebook use this for ad targeting?” — it's good for both a realistic level of risk (most of us are not targeted by the CIA/Mossad/FSB) and a sober assessment of the level of resources available to the attacker.

For blockchains in particular I think we tend underestimate the amount of information which someone with that kind of analytic capacity could derive, especially if they also have other data sources — for example, I would be quite surprised if the various anonymity schemes are less effective when evaluated as part of a full system against someone who has a lot of visibility into web activity (Google Analytics, Facebook beacons), DNS, email, etc.

There are technologies people are working on to solve that. One is called ZK-SNARKS and ethereum is working to integrate the tech. Another is Monero, which is a privacy focused crypto.

Right, I was talking about Bitcoin only. mimblewimble and zcash also both have shielded transactions. I believe they use an ECDH secret for each transaction so that only the two people involved in the transaction can decode it.

If you care about privacy, then consider Monero.

i love when ppl say this. you realize that turning monero into usable cash will at some point req. revealing your identity?

But then the argument is: why would I turn it into usable cash if everyone used it. And by the time you reach that point in the discussion, back slowly away...

the only identifiers i can think of are my height, gait, voice and clothing. Though i get your point and it does seem to be getting harder and harder to find local dealers willing to transact without seeing photo ID. I still think it can be much more private than cash-only purchases, depending on how careful you are about it

Monero does not have this problem. It's what bitcoin should have been.

That’s not an inherent feature of decentralized ledgers; you can have protocols like Zerocash which hide the sender, receiver, amount completely, via the use of zero knowledge proofs