Published on: 2015-05-27T07:30:32+00:00
The email discusses the use of Full Sequence Replace-By-Fee (FSS-RBF) in increasing fees on bitcoin transactions more efficiently than Child Pays For Parent (CPFP). In one case, adding a new input and increasing the change output value can result in cost savings ranging from 11% to 34%+. If an unspent output has a greater value than one of the outputs spent by the original transaction, it can be replaced, resulting in a 34% savings compared to CPFP. In another case, paying multiple recipients requires adding or swapping inputs, which can lead to overall savings of 25%. FSS-RBF can help reduce transaction size and increase cost savings. However, caution must be taken to ensure that at least one input remains unchanged after multiple rounds of this process.A discussion between Gregory Maxwell and Tom Harding addresses the potential risks of transaction replacement in Bitcoin. Harding raises concerns about certain payments being part of larger deals with unknown connections, which could cause issues if paying parties are kicked out or not informed immediately. Maxwell argues that multisig signers have already accepted the possibility of being written out and should not be considered less reliable. They also discuss Kalle's Proof of Payment proposed standard, where one payer in a two-input transaction could boot the other and claim everything for themselves. The conversation suggests that while there are risks associated with transaction replacement, existing mechanisms can mitigate them.Harding expresses confusion about the relationship between bitcoin transactions and real-world "deals" and calls for more specific definitions. He also discusses changing signatures in transactions and its impact on involved parties. Armory simulfunding transactions are mentioned, where one signer's input can be replaced after broadcasting. The consequences of changing inputs in transactions and the importance of warning signers of multi-input transactions are also discussed. The conversation delves into the complexities of bitcoin transactions and the factors influencing them.Maxwell explains the potential consequences of not contributing to a bitcoin transaction. New inputs combined with new or increased outputs can be seen as a second deal sharing the same envelope. If paying parties are kicked out, the entire transaction may be compromised, leading to real-world consequences. For example, in an Armory simulfunding transaction, one payer's input could be replaced after broadcasting, which could cause problems if the receiver cares about the payment source or makes subsequent decisions based on it. Maxwell also mentions the proposed Proof of Payment standard by Kalle, which allows one payer in a two-input transaction to boot the other and claim everything for themselves. However, this may not work as expected in the real world, especially when there are limited tickets available for a concert. The conversation emphasizes the need for caution when changing how an input is signed and highlights that replacement is a new concept requiring stronger warnings than those for 0-conf.The context explains how replacing a bitcoin transaction works and the implications of doing so. It clarifies that RBF applies only to pending transactions in the mempool waiting to be incorporated into a block. If a replacement transaction conflicts with an already confirmed original transaction, it will be rejected as a double spend. Implementations utilizing RBF must have a backup plan to handle the rejection of a replacement transaction as a double spend. Changing the contents of blocks, aside from mining a competing chain, would be a significant change to Bitcoin's design.The context mentions the mempool policy rule in Bitcoin's design, which states that any change to the contents of blocks other than through mining a competing chain would be a substantial alteration to Bitcoin's design.There is a discussion about whether transactions in buried blocks can be overridden or replaced by RBF. First-seen-safe replace-by-fee (FSS RBF) is a compromise between the standard RBF and first-seen mempool behavior. FSS RBF allows higher fee-paying transactions to replace previous transactions if all outputs in the previous transaction are still paid by the replacement. FSS RBF introduces additional criteria for replacing a transaction, such as all outputs existing in the new transaction and being unspent. Various usage scenarios for FSS RBF are mentioned, including increasing the fee on a single transaction and paying multiple recipients in succession. Wallets should treat conflicting incoming transactions as equivalent as long as their owned transaction outputs do not change.In an email conversation between Tom Harding and an unknown recipient, Harding questions the necessity of contributing to a transaction and suggests using another unused input with a larger fee instead. He highlights the unreliability of depending on the signature content of a transaction until it is buried. Harding argues that an inability to replace an input means that one cannot use RBF for additional fees without taking change in more cases. He believes there should be a benefit to this.FSS RBF is explained as a modification to the Bitcoin Core implementation that allows users effective ways to resolve "stuck" transactions and use blockchain space efficiently while maintaining zeroconf behavior.
Updated on: 2023-08-01T12:49:57.529715+00:00