Op 29 sep. 2017, om 05:18 heeft Peter Todd <[email protected]> het volgende geschreven: > > On Thu, Sep 28, 2017 at 03:43:05PM +0300, Sjors Provoost via bitcoin-dev > wrote: >> Peter Todd wrote: >> Perhaps outside the scope of BIP173, but what about baking it into the >> protocol? That way a transaction that's sent too late, simply won't get >> confirmed. This removes the need for refund logic or asking a customer to >> pay just a few extra cents. You could also disallow a second payment. >> >> Two downsides I can think of: >> * privacy, as differences in expiration policy would be visible on chain >> * miners might be able to game it in their interaction with brokers > > This has been discussed many times before; there are *severe* downsides to > making it possible for transactions to become invalid after the fact.
I've heard of that general principe, but I'm having trouble finding a good resource that describes it more precisely. Is it a peer to peer or mempool issue? E.g a transaction might be accepted into the mempool and relayed at one point in time and suddenly become invalid before they're committed to a block? Or that a node receives a transaction, thinks it's invalid because the address already expired, but then receives an older block later which contains that transaction? Once in a block, I don't see how it would become invalid later. But as a miner tries to find a block and updates the timestamp, they would have toss the transaction out at some point. Another objection I can think of, is that the soft fork introducing this change would have to use a transaction type that's non-standard at the moment. This would make it difficult for a non-upgraded node to broadcast such a transaction. The recipient would have to know if the sender has upgraded before communicating an address, which sounds impractical at best. >>> Being just an expiration time, seconds-level resolution is unnecessary, and >>> may give the wrong impression. I'd suggest either: >>> >>> 1) Hour resolution - 2^24 hours = 1914 years >>> 2) Month resolution - 2^16 months = 5458 years >> >> So that's 4.8 characters for hours, or 3.2 for years, plus checksum space? >> The shorter the better. Perhaps one or two bits can be used to specify an >> exponent; a large range seems more useful than high precision. For instance >> a merchant doesn't care if the customer pays within 10:00:00 minutes or >> 10:00:01 minutes and you wouldn't care if your address is valid 50 years or >> 50 years and 3 minutes. This point may be mute if minute level resolution is >> not practical. > > Note that "large range" is a requirement driven by the fact that expiry times > will inevitably be specified absolutely, not relatively: when the range runs > out you need to upgrade the standard. Better to use another character and use > a > range that won't run out any time soon. > > This wouldn't create a need for more checksum space. You're right, relative time makes no sense. So it would take 5 characters to get roughly two minute resolution that lasts for 100 years. Sjors
signature.asc
Description: Message signed with OpenPGP
_______________________________________________ bitcoin-dev mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
