Fill-or-kill transaction

Summary:

The concept of fill-or-kill transactions is not new and has been discussed previously in the Scaling Bitcoin workshop. In Satoshi's implementation of nLockTime, a significant range of timestamps was wasted, which could be used to create a fill-or-kill system. Two new parameters, nLockTime2 and nKillTime, were defined to enable this system. However, this violates present assumptions about transaction validity unless a constraint exists that any output of such an expiry block is not spent for at least 100 blocks. To ensure safety, all outputs of a transaction that can expire should have op_maturity/csv/rcltv of 100, making them as reorg-safe as coinbase transactions. Unfortunately, this does not work well with p2sh. The resolution for the fill-or-kill system is four blocks or 2048s (34m), and the maximum confirmation window is 8188 blocks (56.9 days) or 16,769,024s (48.5 days). Both time-based and height-based nLockTime2 are supported, but height-based OP_CLTV is not compatible with nLockTime2. To spend a height-based OP_CLTV output, users must use the original nLockTime. A new OP_CLTV2 might be required that can verify both nLockTime and nLockTime2.The height-based nLockTime2 will overflow in 55 years, and it is highly likely that a hard fork will occur to implement a better fill-or-kill system. If not, another tx nVersion might be used for another 55 years.

Updated on: 2023-06-10T22:42:03.014753+00:00