Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 1CD94BB3 for ; Tue, 20 Aug 2019 07:09:28 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-wm1-f51.google.com (mail-wm1-f51.google.com [209.85.128.51]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 2EAB212E for ; Tue, 20 Aug 2019 07:09:25 +0000 (UTC) Received: by mail-wm1-f51.google.com with SMTP id v19so1604651wmj.5 for ; Tue, 20 Aug 2019 00:09:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=V8jjYrJULke8m3MFabvyVXK+P003JfzD2VusvE1+yf0=; b=C54IxMuRH6oYVfZ1Oc/sk/c9Z4WFfhRtlow0kFN2SUSFuGSMk6daU9oj6+cxAPrF0b WiAd+FME11bg9m6zxAhzlS9DdTEeViA35BjOG+MopUYZ2yRj8lds2ML++UKa84bimrmU siDtdU5mNzFk1o7PqrD771aDmPnfVP8/K4emownLT0DuT6O/b4Q8wEsFOmpdqToXH2ok /WF1TISQyQe2z/keROpFgk9Fy1rPfprRvwqV42+dFJxD9NBEXZBqw7Goqc0O9VK0ns7s +ct7bUrZ1zOZGLRMSbknSgbFs2tmxQY35NNpsNT5zQ0i1BoNJxxbNYk2qpM/H0WV8JOS B/ZQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=V8jjYrJULke8m3MFabvyVXK+P003JfzD2VusvE1+yf0=; b=HBtoGqBOhaqrIU/hVMNedjlzTINhXwmyhYwimTSI1jyhnmdh5XmmG/Dx+MrfyW/i17 RXN/QqLepzF2M69ukms4lgmFf6gVGj5E+NunjZwleTppc50I8VX/cAQJRznwS3t/uwFj Vt/GPt1GsscAJxTnYMxT3HiQraEgiBZevmn1GYU8VGCOCKs9ijajrC45x/OzovuvVCWh hZmiVIo8YmGuu/kA8tJXHlNhTVfGIy4op5qClwSvRvKnTqRVdH1B7hf5MyqTpM+/IRcm IctheIsK6JQdkIxT6R0MrPqcHfVrLlyQbid/LxstAcovy5TiBqTfM466cOSQXe2ivIW8 Xn3g== X-Gm-Message-State: APjAAAX2OCO8BSfaeqQWpFUtJ3Cc94Y70mNz+YM674UcWqfqEq6piu4N cQ12jWgj4NDsYdkfXUBcxq+ubpYoCRwC5Iodq5A= X-Google-Smtp-Source: APXvYqwLlIz/VXWCcQKk4Vw0QkXU5LEKm8tgoJ9CfNLYyouqKQdRjfKZ8iz6YAE+a7IgfkdGxaRlYR0BfJPjNIPD2+w= X-Received: by 2002:a1c:2ec6:: with SMTP id u189mr23773425wmu.67.1566284963491; Tue, 20 Aug 2019 00:09:23 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: David Vorick Date: Tue, 20 Aug 2019 03:15:24 -0400 Message-ID: To: Pieter Wuille , Bitcoin Protocol Discussion Content-Type: multipart/alternative; boundary="000000000000ddb6cb0590872232" X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, HTML_MESSAGE, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Subject: Re: [bitcoin-dev] Miniscript X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 20 Aug 2019 07:09:28 -0000 --000000000000ddb6cb0590872232 Content-Type: text/plain; charset="UTF-8" Glad to see this post. I have been following Miniscript for some time, and the static analysis that is possible with Miniscript is particularly interesting to me. Today, new Bitcoin applications such as JoinMarket, Wasabi wallet, and Arwen all suffer from a problem of having novel bitcoin scripts. Bitcoin script is not easy to analyze, and historically it has been difficult for me to get comfortable using these applications because I have been unable to convince myself to have complete confidence in the integrity of the transactions these applications want me to sign. Well established applications can eventually overcome this issue for users by getting sufficient expert review and commentary, however this proves as a substantial barrier to entry in an ecosystem that is ideally as open as possible. Miniscript can make a huge difference here. With Miniscript, it possible to create hardware wallets that can perform static analysis on novel miniscripts and provide the user with assurances about the nature of the transactions. A hardware wallet with a Miniscript analyzer may not be able to tell you that a transaction is a CoinJoin transaction, but it will be able to tell you that under all possible scenarios, you end up with just as many coins in your addresses that you started with, modulo some transaction fee. This is a big deal for novel application writers, as it significantly reduces the barrier for them to convince both themselves and others that the code they wrote does not risk user funds being lost, especially if all transactions are being externally analyzed and signed. Miniscript is not of course a complete solution, for example it cannot solve all of the high-risk edge cases that are present in the lightning network, but it is a big step forward and I believe that widespread use of Miniscript would be a huge boon to the Bitcoin ecosystem. On Mon, Aug 19, 2019 at 7:18 PM Pieter Wuille via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > Hi all, > > Miniscript is a project we've been working on for the past year or so, > and is now at a stage where I'd like to get it some more attention. It is > joint > work with Andrew Poelstra and Sanket Sanjalkar. > > It's a language for writing (a subset of) Bitcoin Scripts in a structured > way, > enabling analysis, composition, generic signing and more. > > For example the script > > OP_CHECKSIG OP_IFDUP OP_NOTIF OP_DUP OP_HASH160 > OP_EQUALVERIFY OP_CHECKSIGVERIFY <144> OP_CSV OP_ENDIF > > in Miniscript notation would be > > or_d(c:pk(A),and_v(vc:pk_h(B),older(144))) > > making it human (engineer?) readable that this is a script that permits A > to > take the coins at any time, and B after 1 day. A full description of the > language can be found on the project website > http://bitcoin.sipa.be/miniscript > > Using Miniscript it's possible to: > * Write descriptors for addresses for scripts that implement things more > complicated than multisig. > * Make software that can deal with composition of policies (e.g. have funds > in a 2-of-3 setup where one of the 3 "keys" is itself a policy that > involves > perhaps multiple devices and timeouts). > * Compile complex spending policies to efficient scripts. > * Figure out under what necessary and/or sufficient conditions a script > can be > satisfied. > * Given signatures for a sufficient set of keys (and hash preimages, if > needed), > generically construct a witness for arbitrary scripts, without metadata > apart from the script itself and public keys appearing in it. This means > generic PSBT signers are possible for this class of scripts. > * Compute the bounds on the size of a witness for arbitrary scripts. > * Perform static analysis to see if any of Script's resource limitations > (ops limit, stack size, ...) might interfere with the ability to spend. > * Who knows what else... > > We have two implementations: > * a C++ one (https://github.com/sipa/miniscript) > * a Rust library (https://github.com/apoelstra/rust-miniscript). > > The implementations are a work in progress, but through large scale > randomized > tests we have confidence that the language design and associated witnesses > are > compatible with the existing consensus and standardness rules. > > To be clear: Miniscript is designed for Bitcoin as it exists today > (primarily > P2WSH), and does not need any consensus changes. That said, we plan to > extend > the design to support future script changes Bitcoin may include. > > Cheers, > > -- > Pieter > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > --000000000000ddb6cb0590872232 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Glad to see this post. I have been following Miniscri= pt for some time, and the static
analysis that is possible with M= iniscript is particularly interesting to me.

Today= , new Bitcoin applications such as JoinMarket, Wasabi wallet, and Arwen all=
suffer from a problem of having novel bitcoin scripts. Bitcoin s= cript is not easy to
analyze, and historically it has been diffic= ult for me to get comfortable using these
applications because I = have been unable to convince myself to have complete
confidence i= n the integrity of the transactions these applications want me to sign.

Well established applications can eventually overcome= this issue for users by
getting sufficient expert review and com= mentary, however this proves as a
substantial barrier to entry in= an ecosystem that is ideally as open as possible.

Miniscript can make a huge difference here. With Miniscript, it possible t= o create
hardware wallets that can perform static analysis on nov= el miniscripts and provide
the user with assurances about the nat= ure of the transactions. A hardware wallet
with a Miniscript anal= yzer may not be able to tell you that a transaction is a
CoinJoin= transaction, but it will be able to tell you that under all possible scena= rios,
you end up with just as many coins in your addresses that y= ou started with, modulo
some transaction fee.

This is a big deal for novel application writers, as it significantly= reduces the barrier
for them to convince both themselves and oth= ers that the code they wrote does not
risk user funds being lost,= especially if all transactions are being externally analyzed
and= signed.

Miniscript is not of course a complete so= lution, for example it cannot solve all of the
high-risk edge cas= es that are present in the lightning network, but it is a big step
forward and I believe that widespread use of Miniscript would be a huge b= oon to the
Bitcoin ecosystem.

On Mon, Aug 19, 2019 at 7:= 18 PM Pieter Wuille via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:<= br>
Hi all,

Miniscript is a project we've been working on for the past year or so,<= br> and is now at a stage where I'd like to get it some more attention. It = is joint
work with Andrew Poelstra and Sanket Sanjalkar.

It's a language for writing (a subset of) Bitcoin Scripts in a structur= ed way,
enabling analysis, composition, generic signing and more.

For example the script

=C2=A0 <A> OP_CHECKSIG OP_IFDUP OP_NOTIF OP_DUP OP_HASH160 <hash16= 0(B)>
=C2=A0 OP_EQUALVERIFY OP_CHECKSIGVERIFY <144> OP_CSV OP_ENDIF

in Miniscript notation would be

=C2=A0 or_d(c:pk(A),and_v(vc:pk_h(B),older(144)))

making it human (engineer?) readable that this is a script that permits A t= o
take the coins at any time, and B after 1 day. A full description of the language can be found on the project website http://bitcoin.sipa.be= /miniscript

Using Miniscript it's possible to:
* Write descriptors for addresses for scripts that implement things more =C2=A0 complicated than multisig.
* Make software that can deal with composition of policies (e.g. have funds=
=C2=A0 in a 2-of-3 setup where one of the 3 "keys" is itself a po= licy that involves
=C2=A0 perhaps multiple devices and timeouts).
* Compile complex spending policies to efficient scripts.
* Figure out under what necessary and/or sufficient conditions a script can= be
=C2=A0 satisfied.
* Given signatures for a sufficient set of keys (and hash preimages, if nee= ded),
=C2=A0 generically construct a witness for arbitrary scripts, without metad= ata
=C2=A0 apart from the script itself and public keys appearing in it. This m= eans
=C2=A0 generic PSBT signers are possible for this class of scripts.
* Compute the bounds on the size of a witness for arbitrary scripts.
* Perform static analysis to see if any of Script's resource limitation= s
=C2=A0 (ops limit, stack size, ...) might interfere with the ability to spe= nd.
* Who knows what else...

We have two implementations:
* a C++ one (https://github.com/sipa/miniscript)
* a Rust library (https://github.com/apoelstra/rust-mini= script).

The implementations are a work in progress, but through large scale randomi= zed
tests we have confidence that the language design and associated witnesses = are
compatible with the existing consensus and standardness rules.

To be clear: Miniscript is designed for Bitcoin as it exists today (primari= ly
P2WSH), and does not need any consensus changes. That said, we plan to exte= nd
the design to support future script changes Bitcoin may include.

Cheers,

--
Pieter
_______________________________________________
bitcoin-dev mailing list
= bitcoin-dev@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mail= man/listinfo/bitcoin-dev
--000000000000ddb6cb0590872232--