53 - Disallow 64-byte transactions
BIP: 53 source Layer: Consensus (soft fork) Title: Disallow 64-byte transactions Author: Chris Stewart Comments-URI: https://github.com/bitcoin/bips/wiki/Comments:BIP-0053 Status: Draft Type: Standards Track Created: 2025-04-11 License: BSD-3-Clause Table of ContentsAbstractSpecificationMotivationBlock malleabilityBlock malleability with consensus INVALID transactionsBlock malleability with consensus VALID transactionsAttack on SPV clientsRationaleSPV clientsBackward compatibilityPre-segwit 64-byte transactionsSegwit 64-byte transactionsReference implementationCopyrightAcknowledgements Abstract This BIP describes the rationale for disallowing transactions that are serialized to 64 bytes without the transaction's witness. We describe the weaknesses to the Merkle tree included in Bitcoin block headers, and various exploits for those weaknesses. Specification This BIP disallows Bitcoin transactions that are serialized to 64 bytes in length without their witness. Motivat...