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Comment by makomk | Hacker News Reader

This involves saving an encrypted copy of the message and unencrypted metadata about which identities are messaging each other when to the publicly-accessible Bitcoin Cash blockchain forever. Not only is this rather inefficient (every single full Bitcoin Cash node carries a copy of every user's messaging history forever), it's not good for privacy and definitely not "uncensorable". You're entirely reliant on miners including the messages in blocks and those full nodes giving you a copy of your messages on request.

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The unencrypted metadata is a transaction between Bitcoin addresses, not mapped to any identity. This is similar to the Bitcoin network, where we just know that addresses contain a certain amount of Bitcoin but we cannot identify who the address belongs to. Compared to privacy apps such as Signal or Telegram, they have some metadata about users.

One should think of a message as a small transaction that embeds some encrypted data on the blockchain. Miners are including messages on blocks because they get paid a small miner fee. These transactions are uncensorable because the Bitcoin network is uncensorable. Traffic of apps such as Telegram can be identified and blocked as Russia has done so in the past.

Bitcoins pseudonymous nature is getting weaker daily and blockchain analysis is maturing as a technology, the biggest coin mixer recently admitted that their services were useless and shutdown. There's very few exchanges if any in the western world where you can swap cash for bitcoin and not hand over ID.

Blockchains are forever.

And absolutely terrifying the moment elliptical curves get broken.

When elliptical curves get broken, Bitcoin is also broken. So we think this day is far off.

You can't undo the blockchain by breaking ECC. Everything is still provably written there and stored on computers across the globe, private wallet keys that will be vulnerable, not the history.

Hash functions are considered fairly immune from post-quantum cryptography. Applying Grovers algorithm means SHA-256 ends up with 128 bits of security.

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