Max Hillebrand on Nostr: I think this does not solve the problem for you. Including a recent block hash is a ...
I think this does not solve the problem for you.
Including a recent block hash is a proof of absence, meaning that the note cannot have been created before that block was mined. It proofs the lower bound, that the message is older than that block. The attacker can include a very old blockhash years after it was mined.
What you are looking for instead is a proof of existence, meaning that the note was created before a certain time. You can do this with NIP3 open timestamps, when including a reference to a note ID into a bitcoin transaction and block, you can verify the upper bound, that this note was written before that block was mined. If the attacker now years later proposes a new note with enough proof of work, then he still cannot include this note into the old block, so the attack is deterred.
Of course you can easily combine the two methods, include the recent bitcoin blockhash into your nostr message, then put the note ID into open timestamps. This way you proof both absence and existence, meaning you have a cryptographic proof of the time window when a note was created.
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Repost from github, we really need a nostr git client.
Including a recent block hash is a proof of absence, meaning that the note cannot have been created before that block was mined. It proofs the lower bound, that the message is older than that block. The attacker can include a very old blockhash years after it was mined.
What you are looking for instead is a proof of existence, meaning that the note was created before a certain time. You can do this with NIP3 open timestamps, when including a reference to a note ID into a bitcoin transaction and block, you can verify the upper bound, that this note was written before that block was mined. If the attacker now years later proposes a new note with enough proof of work, then he still cannot include this note into the old block, so the attack is deterred.
Of course you can easily combine the two methods, include the recent bitcoin blockhash into your nostr message, then put the note ID into open timestamps. This way you proof both absence and existence, meaning you have a cryptographic proof of the time window when a note was created.
...
Repost from github, we really need a nostr git client.