BIPs bitcoin improvement proposals

Segwit Output Script Descriptors

  BIP: 382 source
  Layer: Applications
  Title: Segwit Output Script Descriptors
  Author: Pieter Wuille <pieter@wuille.net>
          Andrew Chow <andrew@achow101.com>
  Comments-Summary: No comments yet.
  Comments-URI: https://github.com/bitcoin/bips/wiki/Comments:BIP-0382
  Status: Draft
  Type: Informational
  Created: 2021-06-27
  License: BSD-2-Clause

Table of Contents

Abstract

This document specifies wpkh(), and wsh() output script descriptors. wpkh() descriptors take a key and produces a P2WPKH output script. wsh() descriptors take a script and produces a P2WSH output script.

Copyright

This BIP is licensed under the BSD 2-clause license.

Motivation

Segregated Witness added 2 additional standard output script formats: P2WPKH and P2WSH. These expressions allow specifying those formats as a descriptor.

Specification

Two new script expressions are defined: wpkh(), and wsh().

wpkh()

The wpkh(KEY) expression can be used as a top level expression, or inside of a sh() descriptor. It takes a single key expression as an argument and produces a P2WPKH output script. Only keys which are/has compressed public keys can be contained in a wpkh() expression.

The output script produced is:

OP_0 <KEY_hash160>

wsh()

The wsh(SCRIPT) expression can be used as a top level expression, or inside of a sh() descriptor. It takes a single script expression as an argument and produces a P2WSH output script. wsh() expressions also create a witnessScript which is required in order to spend outputs which use its output script. This redeemScript is the output script produced by the SCRIPT argument to wsh(). Any key expression found in any script expression contained by a wsh() expression must only produce compressed public keys.

The output script produced is:

OP_0 <SCRIPT_sha256>

Test Vectors

TBD

Backwards Compatibility

wpkh(), and wsh() descriptors use the format and general operation specified in 380. As these are a wholly new descriptors, they are not compatible with any implementation. However the scripts produced are standard scripts so existing software are likely to be familiar with them.

Reference Implemntation

wpkh(), and wsh() descriptors have been implemented in Bitcoin Core since version 0.17.