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I am always amazed at the concept that blockchain is private at any level. The architecture is built specifically to share transactional data. It is useful for

I am always amazed at the concept that blockchain is private at any level. The architecture is built specifically to share transactional data. It is useful for creating a digital entity that is unique and can be treated as currency, but the shared transactional nature is a huge, huge privacy flaw, as far as I understand blockchain (at least Bitcoin). Please correct me if I am wrong about the public nature of transactions - I haven't seen anything discussing the encryption of transactions but I am by no means an expert on this. So assuming the transactions are accessible to anyone (and even encrypted is somewhat worrisome), what are the implications? Well, for a while Whole Foods was accepting payment by Bitcoin. That means if you know Whole Foods' Bitcoin account number you could simply look up all transactions to Whole Foods to see how much money they were making through Bitcoin, how many unique accounts paid them as well was when and how much. Does every business want their detailed transaction history to be public? And on a personal level, I remember when Netflix released anonymized data of movie ratings with ratings and date stamps. From this alone, some people were identified by looking at other personalizing data: https://www.wired.com/2007/12/why-anonymous-data-sometimes-isnt/ https://www.wired.com/2007/12/why-anonymous-data-sometimes-i... All it would take is one data harvesting company to pair your account to your transactions and then could track everything you do through it. I really hope this isn't how all of this works... and even if there are protections to prevent this, it seems like a viable attack vector to consider for any blockchain technology.

nybble41 7y ago
> Well, for a while Whole Foods was accepting payment by Bitcoin. That means if you know Whole Foods' Bitcoin account number... They wouldn't have just one "account number". Standard practice is to use a different address for each transaction, both for privacy and for increased security. (An attacker only has the public key hash to work from for any unspent transactions, not the full public key.) Now, these funds would probably be consolidated into a smaller number of holding accounts, and you might be able to deduce some other likely payments to Whole Foods by looking at which inputs were combined together in later transactions, but obtaining their complete ledger is nowhere near as simple as looking at one payment to Whole Foods and finding all the other transactions involving the same address.

nybble41 7y ago

> Well, for a while Whole Foods was accepting payment by Bitcoin. That means if you know Whole Foods' Bitcoin account number... They wouldn't have just one "account number". Standard practice is to use a different address for each transaction, both for privacy and for increased security. (An attacker only has the public key hash to work from for any unspent transactions, not the full public key.) Now, these funds would probably be consolidated into a smaller number of holding accounts, and you might be able to deduce some other likely payments to Whole Foods by looking at which inputs were combined together in later transactions, but obtaining their complete ledger is nowhere near as simple as looking at one payment to Whole Foods and finding all the other transactions involving the same address.