BIP 0382

BIP: 382
 Layer: Applications
 Title: Segwit Output Script Descriptors
 Author: Pieter Wuille <pieter@wuille.net>
 Ava Chow <me@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
==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==
Valid descriptors followed by the scripts they produce. Descriptors involving derived child keys will have the 0th, 1st, and 2nd scripts listed.
* wpkh(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)
** 00149a1c78a507689f6f54b847ad1cef1e614ee23f1e
* wpkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)
** 00149a1c78a507689f6f54b847ad1cef1e614ee23f1e
* wpkh([ffffffff/13']xprv9vHkqa6EV4sPZHYqZznhT2NPtPCjKuDKGY38FBWLvgaDx45zo9WQRUT3dKYnjwih2yJD9mkrocEZXo1ex8G81dwSM1fwqWpWkeS3v86pgKt/1/2/0)
** 0014326b2249e3a25d5dc60935f044ee835d090ba859
* wpkh([ffffffff/13']xpub69H7F5d8KSRgmmdJg2KhpAK8SR3DjMwAdkxj3ZuxV27CprR9LgpeyGmXUbC6wb7ERfvrnKZjXoUmmDznezpbZb7ap6r1D3tgFxHmwMkQTPH/1/2/*)
** 0014326b2249e3a25d5dc60935f044ee835d090ba859
** 0014af0bd98abc2f2cae66e36896a39ffe2d32984fb7
** 00141fa798efd1cbf95cebf912c031b8a4a6e9fb9f27
* sh(wpkh(xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jPPqjiChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHi/10/20/30/40/*'))
** a9149a4d9901d6af519b2a23d4a2f51650fcba87ce7b87
** a914bed59fc0024fae941d6e20a3b44a109ae740129287
** a9148483aa1116eb9c05c482a72bada4b1db24af654387
* sh(wpkh(xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jPPqjiChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHi/10/20/30/40/*h))
** a9149a4d9901d6af519b2a23d4a2f51650fcba87ce7b87
** a914bed59fc0024fae941d6e20a3b44a109ae740129287
** a9148483aa1116eb9c05c482a72bada4b1db24af654387
* wsh(pkh(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1))
** 0020338e023079b91c58571b20e602d7805fb808c22473cbc391a41b1bd3a192e75b
* wsh(pkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))
** 0020338e023079b91c58571b20e602d7805fb808c22473cbc391a41b1bd3a192e75b
* wsh(pk(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1))
** 00202e271faa2325c199d25d22e1ead982e45b64eeb4f31e73dbdf41bd4b5fec23fa
* wsh(pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))
** 00202e271faa2325c199d25d22e1ead982e45b64eeb4f31e73dbdf41bd4b5fec23fa
* sh(wsh(pkh(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)))
** a914b61b92e2ca21bac1e72a3ab859a742982bea960a87
* sh(wsh(pkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)))
** a914b61b92e2ca21bac1e72a3ab859a742982bea960a87
Invalid descriptors with descriptions
* Uncompressed public key in wpkh(): wpkh(5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss)
* Uncompressed public key in wpkh(): sh(wpkh(5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss))
* Uncompressed public key in wpkh(): wpkh(04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235)
* Uncompressed public key in wpkh(): sh(wpkh(04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235))
* Uncompressed public keys under wsh(): wsh(pk(5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss))
* Uncompressed public keys under wsh(): wsh(pk(04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235))
* wpkh() nested in wsh(): wsh(wpkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))
* wsh() nested in wsh(): wsh(wsh(pkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)))
* wsh() nested in wsh(): sh(wsh(wsh(pkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))))
* Script in wpkh(): wpkh(wsh(pkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)))
* Key in wsh(): wsh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)
==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 Implementation==
wpkh(), and wsh() descriptors have been implemented in Bitcoin Core since version 0.17.