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diff --git a/bip-0339.mediawiki b/bip-0339.mediawiki new file mode 100644 index 0000000..806ba1c --- /dev/null +++ b/bip-0339.mediawiki @@ -0,0 +1,59 @@ +<pre> + BIP: 339 + Layer: Peer Services + Title: WTXID-based transaction relay + Author: Suhas Daftuar <sdaftuar@chaincode.com> + Comments-Summary: No comments yet. + Comments-URI: https://github.com/bitcoin/bips/wiki/Comments:BIP-0339 + Status: Draft + Type: Standards Track + Created: 2020-02-03 + License: BSD-2-Clause +</pre> + +==Abstract== + +This BIP describes two changes to the p2p protocol to support transaction relay +based on the BIP 141 wtxid of a transaction, rather than its txid. + +==Motivation== + +Historically, the inv messages sent on the Bitcoin peer-to-peer network to +announce transactions refer to transactions by their txid, which is a hash of +the transaction that does not include the witness (see BIP 141). This has been +the case even since Segregated Witness (BIP 141/143/144) has been adopted by +the network. + +Not committing to the witness in transaction announcements creates +inefficiencies: because a transaction's witness can be malleated without +altering the txid, a node in receipt of a witness transaction that the node +does not accept will generally still download that same transaction when +announced by other peers. This is because the alternative -- of not downloading +a given txid after rejecting a transaction with that txid -- would allow a +third party to interfere with transaction relay by malleating a transaction's +witness and announcing the resulting invalid transaction to nodes, preventing +relay of the valid version of the transaction as well. + +We can eliminate this concern by using the wtxid in place of the txid when +announcing and fetching transactions. + +==Specification== + +# A new wtxidrelay message is added, which is defined as an empty message where pchCommand == "wtxidrelay". +# The protocol version of nodes implementing this BIP must be set to 70016 or higher. +# The wtxidrelay message MUST be sent in response to a version message from a peer whose protocol version is >= 70016 and prior to sending a verack. A wtxidrelay message received after a verack message MUST be ignored or treated as invalid. +# A new inv type MSG_WTX (0x00000005) is added, for use in both inv messages and getdata requests, indicating that the hash being referenced is a transaction's wtxid. In the case of getdata requests, MSG_WTX implies that the transaction being requested should be serialized with witness as well, as described in BIP 144. +# After a node has received a wtxidrelay message from a peer, the node MUST use the MSG_WTX inv type when announcing transactions to that peer. +# After a node has received a wtxidrelay message from a peer, the node SHOULD use a MSG_WTX getdata message to request any announced transactions. A node MAY still request transactions from that peer using MSG_TX getdata messages, such as for transactions not recently announced by that peer (like the parents of recently announced transactions). + +==Backward compatibility== + +As wtxid-based transaction relay is only enabled between peers that both support it, older clients remain fully compatible and interoperable after this change. + +==Implementation== + +https://github.com/bitcoin/bitcoin/pull/18044 + +==Copyright== + +This BIP is licensed under the 2-clause BSD license. |