<pre>
  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
</pre>

==Abstract==

This document specifies <tt>wpkh()</tt>, and <tt>wsh()</tt> output script descriptors.
<tt>wpkh()</tt> descriptors take a key and produces a P2WPKH output script.
<tt>wsh()</tt> 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: <tt>wpkh()</tt>, and <tt>wsh()</tt>.

===<tt>wpkh()</tt>===

The <tt>wpkh(KEY)</tt> expression can be used as a top level expression, or inside of a <tt>sh()</tt> 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 <tt>wpkh()</tt> expression.

The output script produced is:
<pre>
OP_0 <KEY_hash160>
</pre>

===<tt>wsh()</tt>===

The <tt>wsh(SCRIPT)</tt> expression can be used as a top level expression, or inside of a <tt>sh()</tt> descriptor.
It takes a single script expression as an argument and produces a P2WSH output script.
<tt>wsh()</tt> 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 <tt>SCRIPT</tt> argument to <tt>wsh()</tt>.
Any key expression found in any script expression contained by a <tt>wsh()</tt> expression must only produce compressed public keys.

The output script produced is:
<pre>
OP_0 <SCRIPT_sha256>
</pre>

==Test Vectors==

Valid descriptors followed by the scripts they produce. Descriptors involving derived child keys will have the 0th, 1st, and 2nd scripts listed.

* <tt>wpkh(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)</tt>
** <tt>00149a1c78a507689f6f54b847ad1cef1e614ee23f1e</tt>
* <tt>wpkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)</tt>
** <tt>00149a1c78a507689f6f54b847ad1cef1e614ee23f1e</tt>
* <tt>wpkh([ffffffff/13']xprv9vHkqa6EV4sPZHYqZznhT2NPtPCjKuDKGY38FBWLvgaDx45zo9WQRUT3dKYnjwih2yJD9mkrocEZXo1ex8G81dwSM1fwqWpWkeS3v86pgKt/1/2/0)</tt>
** <tt>0014326b2249e3a25d5dc60935f044ee835d090ba859</tt>
* <tt>wpkh([ffffffff/13']xpub69H7F5d8KSRgmmdJg2KhpAK8SR3DjMwAdkxj3ZuxV27CprR9LgpeyGmXUbC6wb7ERfvrnKZjXoUmmDznezpbZb7ap6r1D3tgFxHmwMkQTPH/1/2/*)</tt>
** <tt>0014326b2249e3a25d5dc60935f044ee835d090ba859</tt>
** <tt>0014af0bd98abc2f2cae66e36896a39ffe2d32984fb7</tt>
** <tt>00141fa798efd1cbf95cebf912c031b8a4a6e9fb9f27</tt>
* <tt>sh(wpkh(xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jPPqjiChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHi/10/20/30/40/*'))</tt>
** <tt>a9149a4d9901d6af519b2a23d4a2f51650fcba87ce7b87</tt>
** <tt>a914bed59fc0024fae941d6e20a3b44a109ae740129287</tt>
** <tt>a9148483aa1116eb9c05c482a72bada4b1db24af654387</tt>
* <tt>sh(wpkh(xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jPPqjiChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHi/10/20/30/40/*h))</tt>
** <tt>a9149a4d9901d6af519b2a23d4a2f51650fcba87ce7b87</tt>
** <tt>a914bed59fc0024fae941d6e20a3b44a109ae740129287</tt>
** <tt>a9148483aa1116eb9c05c482a72bada4b1db24af654387</tt>
* <tt>wsh(pkh(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1))</tt>
** <tt>0020338e023079b91c58571b20e602d7805fb808c22473cbc391a41b1bd3a192e75b</tt>
* <tt>wsh(pkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))</tt>
** <tt>0020338e023079b91c58571b20e602d7805fb808c22473cbc391a41b1bd3a192e75b</tt>
* <tt>wsh(pk(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1))</tt>
** <tt>00202e271faa2325c199d25d22e1ead982e45b64eeb4f31e73dbdf41bd4b5fec23fa</tt>
* <tt>wsh(pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))</tt>
** <tt>00202e271faa2325c199d25d22e1ead982e45b64eeb4f31e73dbdf41bd4b5fec23fa</tt>
* <tt>sh(wsh(pkh(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)))</tt>
** <tt>a914b61b92e2ca21bac1e72a3ab859a742982bea960a87</tt>
* <tt>sh(wsh(pkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)))</tt>
** <tt>a914b61b92e2ca21bac1e72a3ab859a742982bea960a87</tt>

Invalid descriptors with descriptions

* Uncompressed public key in <tt>wpkh()</tt>: <tt>wpkh(5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss)</tt>
* Uncompressed public key in <tt>wpkh()</tt>: <tt>sh(wpkh(5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss))</tt>
* Uncompressed public key in <tt>wpkh()</tt>: <tt>wpkh(04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235)</tt>
* Uncompressed public key in <tt>wpkh()</tt>: <tt>sh(wpkh(04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235))</tt>
* Uncompressed public keys under <tt>wsh()</tt>: <tt>wsh(pk(5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss))</tt>
* Uncompressed public keys under <tt>wsh()</tt>: <tt>wsh(pk(04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235))</tt>
* <tt>wpkh()</tt> nested in <tt>wsh()</tt>: <tt>wsh(wpkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))</tt>
* <tt>wsh()</tt> nested in <tt>wsh()</tt>: <tt>wsh(wsh(pkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)))</tt>
* <tt>wsh()</tt> nested in <tt>wsh()</tt>: <tt>sh(wsh(wsh(pkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))))</tt>
* Script in <tt>wpkh()</tt>: <tt>wpkh(wsh(pkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)))</tt>
* Key in <tt>wsh()</tt>: <tt>wsh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)</tt>

==Backwards Compatibility==

<tt>wpkh()</tt>, and <tt>wsh()</tt> descriptors use the format and general operation specified in [[bip-0380.mediawiki|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==

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