Return-Path: Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 436EEC002D for ; Tue, 26 Jul 2022 21:56:24 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 25AAC8175D for ; Tue, 26 Jul 2022 21:56:24 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org 25AAC8175D Authentication-Results: smtp1.osuosl.org; dkim=pass (2048-bit key) header.d=satoshilabs.com header.i=@satoshilabs.com header.a=rsa-sha256 header.s=google header.b=R2s25VRX X-Virus-Scanned: amavisd-new at osuosl.org X-Spam-Flag: NO X-Spam-Score: -2.099 X-Spam-Level: X-Spam-Status: No, score=-2.099 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id xs6SJ9Pi2MSb for ; Tue, 26 Jul 2022 21:56:22 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.8.0 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org A239D8175B Received: from mail-yw1-x1133.google.com (mail-yw1-x1133.google.com [IPv6:2607:f8b0:4864:20::1133]) by smtp1.osuosl.org (Postfix) with ESMTPS id A239D8175B for ; Tue, 26 Jul 2022 21:56:22 +0000 (UTC) Received: by mail-yw1-x1133.google.com with SMTP id 00721157ae682-31f379a0754so54123857b3.2 for ; Tue, 26 Jul 2022 14:56:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=satoshilabs.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=HWuHhDEDS92p9vT7EdAzwe36oWZSlMa7y6/AcO1R4Pw=; b=R2s25VRXgc4pEdd0NxhksEcgVWLYlUXJY3cq/DVOqqG2GjqX3dsUeuJrtkvKVFUhR5 ME2UPAf7xM331BUOcBe7dCnbWgdoueoLMwDa0OXp63Ppu9IWi8qZpsl7p/N3UJpnmilh t9k8kqC6Efy7YAdXwzBi/d44Xl5IpWOKRxN6jiyiNresvmt9hefb5FiNR3reImHrQUS2 FeluKVensr+c1sr+1WUCih2f4sHmcEID/FNlKEm5C0jkFE0XIarUqn2eskxbBdCntLqa xpDiVMZTsJEmbnskdlU2gbW1BoeEJ9Su4j9w7lROcN7rdQYjr0EmXW5TdG7soc2NvZUA EGtA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=HWuHhDEDS92p9vT7EdAzwe36oWZSlMa7y6/AcO1R4Pw=; b=kY0IhWB+Lo2SKbjn5xEYwyfx4D7PrARVDITDpIcd9Zy1jK52RmjYgQrDP6BjzjBST3 sY8Q6427x5j+EUjv6FiZ8UKJJyIFYwDBFU6TyNi+DQQ+at5YVF8wpKJ6KqyFeO68uNsA D+cCw/iXbFjGfvsqIKFK2zAqCNsCCi6BjfGirFjejyCL7HUBWqaG7SQgzfwR9462/4Et WGL45MqafVZfPhcG4aieItgH08nt1LbQqyWy1tFFRZAZbsDLNCePx4Gmu0qngb9SdCiu IkMtmnPRDPMTOVsPBLYrwS+M5kS9rbYWPWfvVRL9u5+g9uL/KLmzPNYe7cM4+U2IrWPS eq1w== X-Gm-Message-State: AJIora+VlozFR58OYy/w4eTFRe7U5d3v4Slik7o869ujVrihA8TCsaxQ FnYu77oxZz6o0BqN4teitvh1TozDvvyC8FrKGCpmJq5Qtu743w== X-Google-Smtp-Source: AGRyM1sr7oigzwhWbfy8Y5c/+R7vt4mWTbRRhnzF3Ar4MpE4nLtsJggG1BIvryT8XHnKIj4Pfd+p5let7Q7Qn57f7T4= X-Received: by 2002:a81:81c1:0:b0:31e:7378:960c with SMTP id r184-20020a8181c1000000b0031e7378960cmr16649656ywf.266.1658872581617; Tue, 26 Jul 2022 14:56:21 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Pavol Rusnak Date: Tue, 26 Jul 2022 23:56:10 +0200 Message-ID: To: Andrew Chow , Bitcoin Protocol Discussion Content-Type: multipart/alternative; boundary="000000000000f4913605e4bc5e81" Subject: Re: [bitcoin-dev] BIP Proposal: Receiving and Change Derivation Paths in a Single Descriptor X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 26 Jul 2022 21:56:24 -0000 --000000000000f4913605e4bc5e81 Content-Type: text/plain; charset="UTF-8" Thanks Andrew for this BIP. We've been already using this for quite some time for Trezor in production. Just one clarification: Should , , ... also work or we only aim to support only tuples of exactly two values? On Tue, 26 Jul 2022 at 23:51, Andrew Chow via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > Hi All, > > I would like to propose a BIP that de-duplicates and simplifies how we > represent descriptors for receiving and change addresses. Under the > existing BIPs, this requires two descriptors, where the vast majority of > the descriptors are the same, except for a single derivation path > element. This proposal allows descriptors to have a single derivation > path element that can specify a pair of indexes. Parsers would then > expand these into two almost identical descriptors with the difference > being that the first uses the first of the pair of indexes, and the > second uses the second. > > The proposed notation is ``. As an example, > `wpkh(xpub.../0/<0;1>/*)` would be expanded into `wpkh(xpub.../0/0/*)` > and `wpkh(xpub.../0/1/*)`. > > This also works for descriptors involving multiple keys - the first > element in every pair is used for the first descriptor, and the second > element of each pair in the second descriptor. > > The full text of the BIP can be found at > > https://github.com/achow101/bips/blob/bip-multipath-descs/bip-multipath-descs.mediawiki > and also copied below. An implementation of it to Bitcoin Core is > available at https://github.com/bitcoin/bitcoin/pull/22838. > > Any feedback on this would be appreciated. > > Thanks, > Andrew Chow > > --- > > 
>    BIP: multipath-descs
>    Layer: Applications
>    Title: Multipath Descriptor Key Expressions
>    Author: Andrew Chow 
>    Comments-Summary: No comments yet.
>    Comments-URI:
> https://github.com/bitcoin/bips/wiki/Comments:BIP-multipath-descs
>    Status: Draft
>    Type: Informational
>    Created: 2022-07-26
>    License: BSD-2-Clause
>
> > ==Abstract== > > This document specifies a modification to Key Expressions of Descriptors > that are described in BIP 380. > This modification allows Key Expressions to indicate BIP 32 derivation > path steps that can have multiple values. > > ==Copyright== > > This BIP is licensed under the BSD 2-clause license. > > ==Motivation== > > Descriptors can describe the scripts that are used in a wallet, but > wallets often require at least two descriptors for all of the scripts > that they watch for. > Wallets typically have one descriptor for producing receiving addresses, > and the other for change addresses. > These descriptors are often extremely similar - they produce the same > types of scripts, derive keys from the same master key, and use > derivation paths that are almost identical. > The only differences are in the derivation path where one of the steps > will be different between the descriptors. > Thus it is useful to have a notation to represent both descriptors as a > single descriptor where one of the derivation steps is a pair of values. > > ==Specification== > > For extended keys and their derivations paths in a Key Expression, BIP > 380 states: > > * xpub encoded extended public key or xprv encoded > extended private key (as defined in BIP 32) > ** Followed by zero or more /NUM or /NUMh path > elements indicating BIP 32 derivation steps to be taken after the given > extended key. > ** Optionally followed by a single /* or /*h final > step to denote all direct unhardened or hardened children. > > This is modifed to state: > > * xpub encoded extended public key or xprv encoded > extended private key (as defined in BIP 32) > ** Followed by zero or more /NUM or /NUMh path > elements indicating BIP 32 derivation steps to be taken after the given > extended key. > ** Followed by zero or one / (NUM may be > followed by h to indicated a hardened step) path element > indicating a pair of BIP 32 derivation steps to be taken after the given > extended key. > ** Followed by zero or more /NUM or /NUMh path > elements indicating BIP 32 derivation steps to be taken after the given > extended key. > ** Optionally followed by a single /* or /*h final > step to denote all direct unhardened or hardened children. > > When a / is encountered, parsers should produce two > descriptors where the first descriptor uses the first NUM, and > a second descriptor uses the second NUM. > > The common use case for this is to represent descriptors for producing > receiving and change addresses. > When interpreting for this use case, wallets should use the first > descriptor for producing receiving addresses, and the second descriptor > for producing change addresses. > For this use case, the element will commonly be the value /<0;1> > > ==Test Vectors== > > TBD > > ==Backwards Compatibility== > > This is an addition to the Key Expressions defined in BIP 380. > Key Expressions using the format described in BIP 380 are compatible > with this modification and parsers that implement this will still be > able to parse such descriptors. > However as this is an addition to Key Expressions, older parsers will > not be able to understand such descriptors. > > This modification to Key Expressions uses two new characters: < > and ;. > These are part of the descriptor character set and so are covered by the > checksum algorithm. > As these are previously unused characters, old parsers will not > accidentally mistake them for indicating something else. > > ==Reference Implementation== > > https://github.com/bitcoin/bitcoin/pull/22838 > > > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > -- Best Regards / S pozdravom, Pavol "stick" Rusnak Co-Founder, SatoshiLabs --000000000000f4913605e4bc5e81 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Thanks Andrew for this BIP. We've been already=C2= =A0using this for quite some time for Trezor in production.

<= /div>
Just one clarification: Should <NUM;NUM;NUM>, <NUM;NUM;N= UM;NUM>, ... also work or we only aim to support only tuples of exactly = two values?

On Tue, 26 Jul 2022 at 23:51, Andrew Chow via bitcoin-dev = <bitcoin-dev@li= sts.linuxfoundation.org> wrote:
Hi All,

I would like to propose a BIP that de-duplicates and simplifies how we
represent descriptors for receiving and change addresses. Under the
existing BIPs, this requires two descriptors, where the vast majority of the descriptors are the same, except for a single derivation path
element. This proposal allows descriptors to have a single derivation
path element that can specify a pair of indexes. Parsers would then
expand these into two almost identical descriptors with the difference
being that the first uses the first of the pair of indexes, and the
second uses the second.

The proposed notation is `<a;b>`. As an example,
`wpkh(xpub.../0/<0;1>/*)` would be expanded into `wpkh(xpub.../0/0/*)= `
and `wpkh(xpub.../0/1/*)`.

This also works for descriptors involving multiple keys - the first
element in every pair is used for the first descriptor, and the second
element of each pair in the second descriptor.

The full text of the BIP can be found at
https://githu= b.com/achow101/bips/blob/bip-multipath-descs/bip-multipath-descs.mediawiki<= /a>
and also copied below. An implementation of it to Bitcoin Core is
available at https://github.com/bitcoin/bitcoin/pull/2= 2838.

Any feedback on this would be appreciated.

Thanks,
Andrew Chow

---

<pre>
=C2=A0=C2=A0 BIP: multipath-descs
=C2=A0=C2=A0 Layer: Applications
=C2=A0=C2=A0 Title: Multipath Descriptor Key Expressions
=C2=A0=C2=A0 Author: Andrew Chow <andrew@achow101.com>
=C2=A0=C2=A0 Comments-Summary: No comments yet.
=C2=A0=C2=A0 Comments-URI:
https://github.com/bitcoin/bips/wik= i/Comments:BIP-multipath-descs
=C2=A0=C2=A0 Status: Draft
=C2=A0=C2=A0 Type: Informational
=C2=A0=C2=A0 Created: 2022-07-26
=C2=A0=C2=A0 License: BSD-2-Clause
</pre>

=3D=3DAbstract=3D=3D

This document specifies a modification to Key Expressions of Descriptors that are described in BIP 380.
This modification allows Key Expressions to indicate BIP 32 derivation
path steps that can have multiple values.

=3D=3DCopyright=3D=3D

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

=3D=3DMotivation=3D=3D

Descriptors can describe the scripts that are used in a wallet, but
wallets often require at least two descriptors for all of the scripts
that they watch for.
Wallets typically have one descriptor for producing receiving addresses, and the other for change addresses.
These descriptors are often extremely similar - they produce the same
types of scripts, derive keys from the same master key, and use
derivation paths that are almost identical.
The only differences are in the derivation path where one of the steps
will be different between the descriptors.
Thus it is useful to have a notation to represent both descriptors as a
single descriptor where one of the derivation steps is a pair of values.
=3D=3DSpecification=3D=3D

For extended keys and their derivations paths in a Key Expression, BIP
380 states:

* <tt>xpub</tt> encoded extended public key or <tt>xprv&l= t;/tt> encoded
extended private key (as defined in BIP 32)
** Followed by zero or more <tt>/NUM</tt> or <tt>/NUMh<= ;/tt> path
elements indicating BIP 32 derivation steps to be taken after the given
extended key.
** Optionally followed by a single <tt>/*</tt> or <tt>/*h= </tt> final
step to denote all direct unhardened or hardened children.

This is modifed to state:

* <tt>xpub</tt> encoded extended public key or <tt>xprv&l= t;/tt> encoded
extended private key (as defined in BIP 32)
** Followed by zero or more <tt>/NUM</tt> or <tt>/NUMh<= ;/tt> path
elements indicating BIP 32 derivation steps to be taken after the given
extended key.
** Followed by zero or one <tt>/<NUM;NUM></tt> (<tt>= ;NUM</tt> may be
followed by <tt>h</tt> to indicated a hardened step)=C2=A0 path= element
indicating a pair of BIP 32 derivation steps to be taken after the given extended key.
** Followed by zero or more <tt>/NUM</tt> or <tt>/NUMh<= ;/tt> path
elements indicating BIP 32 derivation steps to be taken after the given
extended key.
** Optionally followed by a single <tt>/*</tt> or <tt>/*h= </tt> final
step to denote all direct unhardened or hardened children.

When a <tt>/<NUM;NUM></tt> is encountered, parsers should= produce two
descriptors where the first descriptor uses the first <tt>NUM</tt&= gt;, and
a second descriptor uses the second <tt>NUM</tt>.

The common use case for this is to represent descriptors for producing
receiving and change addresses.
When interpreting for this use case, wallets should use the first
descriptor for producing receiving addresses, and the second descriptor
for producing change addresses.
For this use case, the element will commonly be the value <tt>/<0;= 1></tt>

=3D=3DTest Vectors=3D=3D

TBD

=3D=3DBackwards Compatibility=3D=3D

This is an addition to the Key Expressions defined in BIP 380.
Key Expressions using the format described in BIP 380 are compatible
with this modification and parsers that implement this will still be
able to parse such descriptors.
However as this is an addition to Key Expressions, older parsers will
not be able to understand such descriptors.

This modification to Key Expressions uses two new characters: <tt><= ;</tt>
and <tt>;</tt>.
These are part of the descriptor character set and so are covered by the checksum algorithm.
As these are previously unused characters, old parsers will not
accidentally mistake them for indicating something else.

=3D=3DReference Implementation=3D=3D

https://github.com/bitcoin/bitcoin/pull/22838


_______________________________________________
bitcoin-dev mailing list
= bitcoin-dev@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mail= man/listinfo/bitcoin-dev


--
Best Regards / S pozdravom,

Pavol "sti= ck" Rusnak
Co-Founder, SatoshiLabs
--000000000000f4913605e4bc5e81--