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Blockchains and privacy are antithetical. The whole purpose of a blockchain is to keep track of transactions so that everyone knows how many coins everyone else

by lottin 6y ago

Blockchains and privacy are antithetical. The whole purpose of a blockchain is to keep track of transactions so that everyone knows how many coins everyone else has in order to prevent double-spending. You can try to achieve anonymity through obscurity but this will never work in principle or in practice.

kjjjjjjjjjjjjjj 6y ago
Sure, this applies for bitcoin, because bitcoin is legacy technology and has no features or utility. Monero does not work like bitcoin https://steemit.com/monero/@sgp/7yjqso-a-monero-introduction-for-beginners https://steemit.com/monero/@sgp/7yjqso-a-monero-introduction...
derefr 6y ago
The process of reaching consensus on the current state doesn’t have to involve reaching consensus on the past state for all participants. A blockchain can be built such that all historical previous state + the txs required to get to those historical states are discarded after a quorum of nodes reach consensus on it, leaving only the current state. (This is basically what already happens if you do a “network version upgrade” on a Cosmos-based network: everyone keeps their balances, but just in the form of a new genesis block that all the nodes from the previous generation of the network separately deterministically generated from the state, but which new nodes have to just trust. If you join the network during the new generation, you just download the new genesis, and so can’t “see back” past that point.) Just make the whole network do an automatic “network upgrade” every block — and keep all the state in-memory in the meantime — and now you’ve got a blockchain with forward secrecy. (To be clear: nobody’s done this yet.)
- stjohnswarts 6y ago
  wouldn't mean there wouldn't be any rolling back by consensus since there is nothing to roll back in case of an issue? Wouldn't the software have to perfectly retain state in the present since it always deletes old transactions?
- lottin 6y ago
  Honestly I don't see how this would help. If every bit of transaction history is public at some point in time, then the transaction history is public, since it is impossible to make someone forcefully forget something.
  - derefr 6y ago
    Transactions don’t need to ever be broadcast to the network as a whole (e.g. via a gossip protocol) — they only need to be submitted directly to the quorum that will execute them. Think about physical replication in a DBMS: you only need to transact with the master. Physical replication receivers don’t see logical TXs; they just see the new state (= WAL segments) that the master decided on. Of course, in a Proof-of-Work network, the quorum could be anybody, so your OPSEC is “leaky” — it’s like having forward-secrecy enabled on a public chatroom that anyone can enter and sit in listening/recording. But in a Proof-of-Stake or Proof-of-Authority network, the quorum only consists of the stakeholders. So, as long as the stakeholders all intentionally discard transactions, then there’s nobody to recover the data from. It’s very similar to private corporations whose service involves intentionally discaring (or avoiding logging) user interactions, e.g. “private” / “anonymous” email services. Just scaled into a federated, “open-but-audited membership” system. In such a system, network governance would likely declare that new stakeholders must have their infrastructure setup security-audited by auditors chosen by the existing stakeholders, at the new stakeholder’s expense, before being allowed to run as a validator for the network.

by lottin 6y ago

kjjjjjjjjjjjjjj 6y ago

Sure, this applies for bitcoin, because bitcoin is legacy technology and has no features or utility. Monero does not work like bitcoin https://steemit.com/monero/@sgp/7yjqso-a-monero-introduction-for-beginners https://steemit.com/monero/@sgp/7yjqso-a-monero-introduction...

derefr 6y ago

The process of reaching consensus on the current state doesn’t have to involve reaching consensus on the past state for all participants. A blockchain can be built such that all historical previous state + the txs required to get to those historical states are discarded after a quorum of nodes reach consensus on it, leaving only the current state. (This is basically what already happens if you do a “network version upgrade” on a Cosmos-based network: everyone keeps their balances, but just in the form of a new genesis block that all the nodes from the previous generation of the network separately deterministically generated from the state, but which new nodes have to just trust. If you join the network during the new generation, you just download the new genesis, and so can’t “see back” past that point.) Just make the whole network do an automatic “network upgrade” every block — and keep all the state in-memory in the meantime — and now you’ve got a blockchain with forward secrecy. (To be clear: nobody’s done this yet.)

stjohnswarts 6y ago
wouldn't mean there wouldn't be any rolling back by consensus since there is nothing to roll back in case of an issue? Wouldn't the software have to perfectly retain state in the present since it always deletes old transactions?
lottin 6y ago
Honestly I don't see how this would help. If every bit of transaction history is public at some point in time, then the transaction history is public, since it is impossible to make someone forcefully forget something.
- derefr 6y ago
  Transactions don’t need to ever be broadcast to the network as a whole (e.g. via a gossip protocol) — they only need to be submitted directly to the quorum that will execute them. Think about physical replication in a DBMS: you only need to transact with the master. Physical replication receivers don’t see logical TXs; they just see the new state (= WAL segments) that the master decided on. Of course, in a Proof-of-Work network, the quorum could be anybody, so your OPSEC is “leaky” — it’s like having forward-secrecy enabled on a public chatroom that anyone can enter and sit in listening/recording. But in a Proof-of-Stake or Proof-of-Authority network, the quorum only consists of the stakeholders. So, as long as the stakeholders all intentionally discard transactions, then there’s nobody to recover the data from. It’s very similar to private corporations whose service involves intentionally discaring (or avoiding logging) user interactions, e.g. “private” / “anonymous” email services. Just scaled into a federated, “open-but-audited membership” system. In such a system, network governance would likely declare that new stakeholders must have their infrastructure setup security-audited by auditors chosen by the existing stakeholders, at the new stakeholder’s expense, before being allowed to run as a validator for the network.