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Transactions

Transaction format and validation. 40 proposals.

  • BIP 11: M-of-N Standard Transactions: Deployed. Made "M-of-N" transactions, which require any M signatures out of N possible keys, a standard type that nodes relay. This enabled shared-control arrangements such as escrow or wallets needing two of…
  • BIP 12: OP_EVAL: Closed. Proposed a new script command, OP_EVAL, that would let the receiver of coins define the conditions for spending them instead of the sender. It was abandoned over security concerns and replaced by…
  • BIP 16: Pay to Script Hash: Deployed. Introduced Pay to Script Hash (P2SH), letting a sender pay to a short fingerprint of spending rules that the recipient reveals only when spending. This shifted the cost and complexity of setups like…
  • BIP 31: Pong message: Deployed. Adds a "pong" reply that a node sends back when it receives a "ping" containing a random number. This lets software reliably tell whether a connection to another node is still alive.
  • BIP 47: Reusable Payment Codes for Hierarchical Deterministic Wallets: Deployed. Introduces reusable payment codes that someone can publish once, for example on a website, without the privacy loss of reusing an address. Senders use the code to derive fresh addresses for each…
  • BIP 53: Disallow 64-byte transactions: Draft. Proposes making transactions that are exactly 64 bytes long (excluding signature data) invalid. Such transactions can be confused with internal pieces of a block's Merkle tree, the structure…
  • BIP 54: Consensus Cleanup: Complete. Bundles fixes for several long-standing protocol weaknesses: the timewarp attack (manipulating block timestamps to speed up coin issuance), blocks that take extremely long to validate, Merkle tree…
  • BIP 60: Fixed Length "version" Message (Relay-Transactions Field): Closed. Proposed making the "relay transactions" flag a fixed, always-present part of the initial handshake message rather than an optional extra. The optional field, introduced by BIP 37, made message…
  • BIP 61: Reject P2P message: Deployed. Adds a "reject" message so a node can tell a peer why it refused a transaction or block. This made troubleshooting easier for wallet and node developers, though Bitcoin Core later removed the message.
  • BIP 62: Dealing with malleability: Closed. Proposed a set of rules to stop third parties from altering a transaction's ID without changing what it does, a problem called malleability. It was withdrawn after Segregated Witness (SegWit) solved…
  • BIP 70: Payment Protocol: Deployed. Defines a payment protocol in which a merchant sends a signed payment request directly to the customer's wallet. It aimed to improve checkout and protect against attackers swapping addresses, though…
  • BIP 77: Async Payjoin: Draft. Introduces a second version of Payjoin that works asynchronously, so sender and receiver do not need to be online at the same moment. An untrusted relay called a directory server passes encrypted…
  • BIP 78: A Simple Payjoin Proposal: Deployed. Defines Payjoin, a way for the payer and the recipient to both contribute coins to a single payment transaction. Because the result looks like an ordinary payment but breaks common assumptions used…
  • BIP 79: Bustapay :: a practical coinjoin protocol: Closed. Describes Bustapay, a simple protocol in which the sender and receiver of a payment jointly build and sign the transaction, each adding their own coins. Mixing ownership this way undermines the…
  • BIP 89: Chain Code Delegation: Deployed. Describes a technique for multisignature wallets in which one main participant keeps certain key-derivation information to themselves and gives co-signers only what they need for each signature.…
  • BIP 107: Dynamic limit on the block size: Closed. Proposed a block size limit that adjusts automatically according to the volume of transactions on the network. The aim was to expand capacity when demand is high while avoiding a fixed number that…
  • BIP 114: Merkelized Abstract Syntax Tree: Closed. Proposed MAST, which organizes a script's possible spending conditions into a tree so that only the condition actually used needs to be revealed. This saves space and improves privacy by hiding…
  • BIP 125: Opt-in Full Replace-by-Fee Signaling: Deployed. Defines how a sender can mark an unconfirmed transaction as replaceable, so nodes will accept a new version paying a higher fee. This 'replace-by-fee' lets users speed up a transaction stuck because…
  • BIP 131: "Coalescing Transaction" Specification (wildcard inputs): Closed. Proposed a new kind of transaction that could spend all coins sent to an address at once using a single 'wildcard' input. This would make consolidating many small payments much cheaper, but would…
  • BIP 136: Bech32 Encoded Tx Position References: Draft. Defines "TxRef," a short, human-friendly code that points to a confirmed transaction by its location in the blockchain (block and position) rather than by its long ID. It uses the same…
  • BIP 140: Normalized TXID: Closed. Proposes a "normalized" transaction ID calculated without the signature data, so the ID cannot be changed by tampering with signatures. This would eliminate transaction malleability, which…
  • BIP 151: Peer-to-Peer Communication Encryption: Closed. Proposed encrypting the traffic between Bitcoin nodes so that internet providers and eavesdroppers could not easily read or tamper with it. This early design was later superseded by the version 2…
  • BIP 174: Partially Signed Bitcoin Transaction Format: Deployed. Defines PSBT (Partially Signed Bitcoin Transaction), a standard file format for a transaction that is still collecting signatures. It lets different wallets, hardware devices, and co-signers pass a…
  • BIP 176: Bits Denomination: Complete. Proposes "bits" as the standard name for one millionth of a bitcoin (100 satoshis). The goal is to make everyday amounts easier to express without long strings of decimal places.
  • BIP 179: Name for payment recipient identifiers: Complete. Suggests replacing the word "address" with "invoice" or "invoice address." Because Bitcoin addresses are meant to be used only once, the authors argue the new term better discourages address reuse,…
  • BIP 197: Hashed Time-Locked Collateral Contract: Draft. Describes a script for collateral-backed loans built on hashed time-locked contracts, based on the Atomic Loans design. It lets a borrower lock bitcoin as collateral for a loan with rules enforced…
  • BIP 327: MuSig2 for BIP340-compatible Multi-Signatures: Deployed. Standardizes MuSig2, a scheme that lets several people jointly create a single signature that looks like an ordinary one-person Taproot signature. This makes shared-control wallets cheaper and more…
  • BIP 330: Transaction announcements reconciliation: Draft. Specifies a method for two nodes to efficiently work out which transactions the other is missing, instead of announcing each one individually. It is a building block for Erlay, which would let nodes…
  • BIP 331: Ancestor Package Relay: Draft. Lets nodes request and share an unconfirmed transaction together with the parent transactions it depends on, as a single package. This helps low-fee parents get relayed when a child pays extra fees…
  • BIP 337: Compressed Transactions: Draft. Proposes a compression scheme that can shrink Bitcoin transactions to less than half their usual size. This is useful when bandwidth is very limited, such as broadcasting transactions over satellite…
  • BIP 339: WTXID-based transaction relay: Deployed. Nodes share new transactions by announcing short identifiers, and this change lets them use the "wtxid", an identifier that also covers a transaction's SegWit signature data. The older identifier…
  • BIP 370: PSBT Version 2: Deployed. Updates the Partially Signed Bitcoin Transaction (PSBT) format, a standard file for passing an unfinished transaction between wallets and signing devices. Version 2 allows inputs and outputs to be…
  • BIP 371: Taproot Fields for PSBT: Deployed. Adds Taproot-related information to the Partially Signed Bitcoin Transaction (PSBT) format that wallets use to hand transactions to signers. This lets hardware wallets and other signing tools…
  • BIP 372: Pay-to-contract tweak fields for PSBT: Draft. Adds fields to the Partially Signed Bitcoin Transaction (PSBT) format for 'pay-to-contract' data, extra information used when a key has been mathematically adjusted to commit to some contract or…
  • BIP 386: tr() Output Script Descriptors: Deployed. Defines the descriptor function for Taproot outputs, combining a main key with an optional tree of alternative spending conditions. This gives wallets a standard way to describe, back up and recover…
  • BIP 387: Tapscript Multisig Output Script Descriptors: Deployed. Defines descriptor functions for multisignature setups inside Taproot scripts, which require a different construction than older multisig. One form keeps keys in the given order and the other sorts…
  • BIP 431: Topology Restrictions for Pinning: Draft. Explains 'pinning', a problem where someone can block a transaction from being replaced with a higher-fee version, which can endanger time-sensitive protocols like Lightning. It describes stricter…
  • BIP 433: Pay to Anchor (P2A): Draft. Defines Pay to Anchor, a tiny standard output that anyone can spend without a signature. Its purpose is to act as a hook for fee-bumping: by spending it in a follow-up transaction, any party can add…
  • BIP 446: OP_TEMPLATEHASH: Draft. Proposes OP_TEMPLATEHASH, a Taproot script instruction that produces a fingerprint of the transaction spending a coin. Scripts can use it to require that coins be spent only in a specific pre-agreed…
  • BIP 448: Taproot-native (Re)bindable Transactions: Draft. Bundles three small script instructions, OP_TEMPLATEHASH, OP_CHECKSIGFROMSTACK and OP_INTERNALKEY, into a single proposed upgrade. Together they would let transactions commit to specific future…