0-conf requires decentralised consensus of time in order to determine the order and time of each transaction.

Bitcoin has a block time of 10 minutes achieved by brute forcing hashing algorithms of variable difficulty at enormous scale with a difficulty optimised for it to be solved in ~10 mins. This is what gives the currency its security.

With decentralised time consensus such as that required for 0-conf, would it not theoretically be possible to enforce a 10 minute block time by instead implementing the following conditions:

  • Each block submission must contain at least one transaction that has been entered 9mins 55secs after the previous block (ie: No incentive to mine until 5 seconds before 10 min block time)
  • Difficulty optimised to allow the network to solve the block within ~5 seconds
  • In the case of conflict within the 5 second challenge period, lowest hash in bit value wins
  • In the case of conflict after the 5 second challenge period, first hash wins
  • Network decides any further split in consensus thereafter by longest chain as it does now

Assuming this would be doable, would it not technically be possible to secure Bitcoin with the same hashrate it has now, but consume 0.0083% as much power, and make mining far more profitable for miners (especially in countries that don't have cheap energy) with no loss of security?

  • 3
    '0-conf' is inherently insecure, don't listen to anyone trying to tell you otherwise. After all, If it was secure, then why would we need a blockchain record? (ie, as Anonymous wrote, the blockchain is the timestamp)
    – chytrik
    Jan 12 '19 at 10:41

Mining is the timestamp in Bitcoin, it allows for a decentralized system to achieve synchronized ordering of transactions with high probability. If a system for doing decentralized time sync existed there would be no need for mining blocks at all, you'd simply timestamp transactions as they arrived and call it a day.

No system for this exists, hence we use Proof of Work to achieve an approximation.

  • Can't comment inline because not enough reputation, but Satoshi himself spoke both cautiously and positively of zero-conf, his sentiments more or less being "don't immediately part with expensive goods without a confirmation, but it's probably fine for a cup of coffee." The "mining is the timestamp" answer ignores the initial premise of the question that you have already solved for decentralised time consensus required for secure zero-conf to exist. I don't see why this wouldn't be possible?
    – Mobiliseme
    Jan 13 '19 at 2:41
  • If we assume things which don't exist, we might as well ask hypothetical questions contingent on magic. Decentralized time does not exist, which is why Bitcoin exists, as an approximation. If its easy, great, explain how.
    – Claris
    Jan 14 '19 at 8:40

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