Re: Bitcoin scripting language extensions, collaboration requested

Robbert van Dalen <[email protected]> Wed, 29 Jan 2014 09:12:02 +0100
Newsgroups gmane.comp.lang.concatenative
Message-ID <[email protected]>
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Hi,

I=92ve developed (but stopped maintaining) the Enchilada programming langua=
ge which more or less covers requirements b) c) and d).
Enchilada is (dynamically) mono-typed and homoiconic: evaluations and code =
are also data.

Proving things in Enchilada should - to some extend - be possible, because =
of:

1) pure (rule) rewriting semantics
2) every operator is a pure and total function

I=92m not suggesting that Enchilada is a perfect fit, but I do think some o=
f Enchilada=92s rationale/design decisions may be of interest to you.

Cheers,
Robbert.

On 29 Jan 2014, at 00:34, Mark Friedenbach <[email protected]> wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>=20
> Hi,
>=20
> My name is Mark Friedenbach and I am a bitcoin-core developer [1]. You
> probably know Bitcoin as a peer-to-peer protocol for the digital
> money. What you may not know is that Bitcoin uses a simple,
> Forth-derived but crippled concatenative language for encoding smart
> contracts representing the terms and conditions for transferring
> ownership of digital goods.
>=20
> I'm part of a small volunteer team that is looking at ways we can
> extend the Bitcoin protocol so as to be able to perform a broader
> range of financial services. For example, a more expressive scripting
> language could enable attaching conditionals / "covenants" to assets
> which stay with them even as they transfer owners, e.g. a restricted
> buy-back option for an IOU certificate, which lets the debtor pay off
> the loan without requiring permission of the owner of the debt or
> impacting his/her rights in any other way. This is not currently
> possible in Bitcoin.
>=20
> We would like to prototype a replacement contract scripting language
> for Bitcoin derived from Joy, or any one of the other purely
> functional concatenative languages I see discussed in this list's
> archives. This is a chance to help secure and extend the capabilities
> of a $10 billion economy, and to make an expressive concatenative
> language which will be used by the financial industry for decades to come=
.
>=20
> There are also some interesting requirements that we must place on
> such a language:
>=20
> a. The language must be strongly typed with a decidable type system
> capable of constructing proofs of nontrivial properties. Examples
> beyond ordinary type safety verification might include: proving that
> the scripts requirements can be met solely with knowledge of a set of
> signature-generating private keys, or proving the opposite (that a
> script is unspendable); proving that a script has a constraint
> attached (e.g. cannot be spent before block height N, or simple
> restricted buy-back capability) which can then be pattern matched
> against a whitelist of acceptable constraints.
>=20
> b. The script must be simple, as thousands of nodes world-wide running
> multiple implementations will need to reach global consensus over not
> just the outcome of a script, but also some aspects of the execution
> (e.g. an instruction counter). Consensus failures whether due to bugs
> or faulty designs can lead to unsecured payment networks and possible
> losses in the millions of dollars or more. Interpreter escape would be
> absolutely catastrophic. So simple, minimal, but expressive
> architectures with simple fail-safe implementations are to be
> preferred over complex but user-friendly (RISC is better than CISC).
>=20
> c. The language must support the various cryptographic primitives
> necessary for performing core bitcoin functions. Mostly this just
> means adding a handful of builtin words for performing strong
> cryptographic hashes and elliptic curve signature verification, but
> there are some requirements on the language design as well, chiefly in
> making decisions about how the stack is represented for hash
> operations and in supporting authenticated data structures as
> primitive types for external state.
>=20
> d. Merkle structured compiled form [2]. A script containing quoted
> forms may be considered a hierarchical structure, and Merkle
> compression allows us to reduce such a script to a single root hash
> value (to be placed in the output of a bitcoin transaction) or to
> "prune" execution pathways which are not taken when the script is
> instantiated at spend time, either to compress a large script or to
> provide privacy over the data in branches not taken.
>=20
> The requirements (a) and (b) are probably the most interesting for
> this list. I must admit that type theory is outside of my area of
> expertise. I know only enough to know that we need it, but not enough
> to design such a system myself. I imagine that it must also be an
> interesting challenge to design a minimalistic language that is
> trivial to implement, but still capable of generating expressive,
> compact, readable programs.
>=20
> If anyone here is interested in collaborating with us, or even just
> sharing their experience in comments, we'd appreciate it very much!
>=20
> Happy hacking,
> Mark Friedenbach
>=20
> [1]: Bitcoin is a peer-to-peer currency and payment protocol:
> http://bitcoin.org/
>=20
> [2]: By analogy to the Merkle hash-tree:
> http://en.wikipedia.org/wiki/Merkle_tree
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>=20


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      <p>Hi,<div><br></div><div>I=92ve developed (but stopped maintaining) =
the&nbsp;<a href=3D"http://www.enchiladacode.nl">Enchilada programming</a>&=
nbsp;language which more or less covers requirements b) c) and d).</div><di=
v>Enchilada is (dynamically) mono-typed and&nbsp;homoiconic: evaluations an=
d code are also data.</div><div><br></div><div>Proving things in Enchilada =
should - to some extend - be possible, because of:</div><div><br></div><div=
>1) pure (rule) rewriting semantics</div><div>2) every operator is a pure a=
nd total function</div><div><br></div><div>I=92m not suggesting that Enchil=
ada is a perfect fit, but I do think some of Enchilada=92s rationale/design=
 decisions may be of interest to you.</div><div><br></div><div>Cheers,</div=
><div>Robbert.</div><div><br></div><div>On 29 Jan 2014, at 00:34, Mark Frie=
denbach &lt;<a href=3D"mailto:[email protected]">[email protected]</a>&gt; wr=
ote:<br><br><blockquote type=3D"cite">-----BEGIN PGP SIGNED MESSAGE-----<br=
>Hash: SHA1<br><br>Hi,<br><br>My name is Mark Friedenbach and I am a bitcoi=
n-core developer [1]. You<br>probably know Bitcoin as a peer-to-peer protoc=
ol for the digital<br>money. What you may not know is that Bitcoin uses a s=
imple,<br>Forth-derived but crippled concatenative language for encoding sm=
art<br>contracts representing the terms and conditions for transferring<br>=
ownership of digital goods.<br><br>I'm part of a small volunteer team that =
is looking at ways we can<br>extend the Bitcoin protocol so as to be able t=
o perform a broader<br>range of financial services. For example, a more exp=
ressive scripting<br>language could enable attaching conditionals / "covena=
nts" to assets<br>which stay with them even as they transfer owners, e.g. a=
 restricted<br>buy-back option for an IOU certificate, which lets the debto=
r pay off<br>the loan without requiring permission of the owner of the debt=
 or<br>impacting his/her rights in any other way. This is not currently<br>=
possible in Bitcoin.<br><br>We would like to prototype a replacement contra=
ct scripting language<br>for Bitcoin derived from Joy, or any one of the ot=
her purely<br>functional concatenative languages I see discussed in this li=
st's<br>archives. This is a chance to help secure and extend the capabiliti=
es<br>of a $10 billion economy, and to make an expressive concatenative<br>=
language which will be used by the financial industry for decades to come.<=
br><br>There are also some interesting requirements that we must place on<b=
r>such a language:<br><br>a. The language must be strongly typed with a dec=
idable type system<br>capable of constructing proofs of nontrivial properti=
es. Examples<br>beyond ordinary type safety verification might include: pro=
ving that<br>the scripts requirements can be met solely with knowledge of a=
 set of<br>signature-generating private keys, or proving the opposite (that=
 a<br>script is unspendable); proving that a script has a constraint<br>att=
ached (e.g. cannot be spent before block height N, or simple<br>restricted =
buy-back capability) which can then be pattern matched<br>against a whiteli=
st of acceptable constraints.<br><br>b. The script must be simple, as thous=
ands of nodes world-wide running<br>multiple implementations will need to r=
each global consensus over not<br>just the outcome of a script, but also so=
me aspects of the execution<br>(e.g. an instruction counter). Consensus fai=
lures whether due to bugs<br>or faulty designs can lead to unsecured paymen=
t networks and possible<br>losses in the millions of dollars or more. Inter=
preter escape would be<br>absolutely catastrophic. So simple, minimal, but =
expressive<br>architectures with simple fail-safe implementations are to be=
<br>preferred over complex but user-friendly (RISC is better than CISC).<br=
><br>c. The language must support the various cryptographic primitives<br>n=
ecessary for performing core bitcoin functions. Mostly this just<br>means a=
dding a handful of builtin words for performing strong<br>cryptographic has=
hes and elliptic curve signature verification, but<br>there are some requir=
ements on the language design as well, chiefly in<br>making decisions about=
 how the stack is represented for hash<br>operations and in supporting auth=
enticated data structures as<br>primitive types for external state.<br><br>=
d. Merkle structured compiled form [2]. A script containing quoted<br>forms=
 may be considered a hierarchical structure, and Merkle<br>compression allo=
ws us to reduce such a script to a single root hash<br>value (to be placed =
in the output of a bitcoin transaction) or to<br>"prune" execution pathways=
 which are not taken when the script is<br>instantiated at spend time, eith=
er to compress a large script or to<br>provide privacy over the data in bra=
nches not taken.<br><br>The requirements (a) and (b) are probably the most =
interesting for<br>this list. I must admit that type theory is outside of m=
y area of<br>expertise. I know only enough to know that we need it, but not=
 enough<br>to design such a system myself. I imagine that it must also be a=
n<br>interesting challenge to design a minimalistic language that is<br>tri=
vial to implement, but still capable of generating expressive,<br>compact, =
readable programs.<br><br>If anyone here is interested in collaborating wit=
h us, or even just<br>sharing their experience in comments, we'd appreciate=
 it very much!<br><br>Happy hacking,<br>Mark Friedenbach<br><br>[1]: Bitcoi=
n is a peer-to-peer currency and payment protocol:<br><a href=3D"http://bit=
coin.org/">http://bitcoin.org/</a><br><br>[2]: By analogy to the Merkle has=
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    float: left;
    font-family: Verdana;
    font-size: 10px;
    padding: 10px;
  }

  #activity span {
    font-weight: 700;
  }

  #activity span:first-child {
    text-transform: uppercase;
  }

  #activity span a {
    color: #5085b6;
    text-decoration: none;
  }

  #activity span span {
    color: #ff7900;
  }

  #activity span .underline {
    text-decoration: underline;
  }

  .attach {
    clear: both;
    display: table;
    font-family: Arial;
    font-size: 12px;
    padding: 10px 0;
    width: 400px;
  }

  .attach div a {
    text-decoration: none;
  }

  .attach img {
    border: none;
    padding-right: 5px;
  }

  .attach label {
    display: block;
    margin-bottom: 5px;
  }

  .attach label a {
    text-decoration: none;
  }
=20=20
  blockquote {
    margin: 0 0 0 4px;
  }

  .bold {
    font-family: Arial;
    font-size: 13px;
    font-weight: 700;
  }

  .bold a {
    text-decoration: none;
  }

  dd.last p a {
    font-family: Verdana;
    font-weight: 700;
  }

  dd.last p span {
    margin-right: 10px;
    font-family: Verdana;
    font-weight: 700;
  }

  dd.last p span.yshortcuts {
    margin-right: 0;
  }

  div.attach-table div div a {
    text-decoration: none;
  }

  div.attach-table {
    width: 400px;
  }

  div.file-title a, div.file-title a:active, div.file-title a:hover, div.fi=
le-title a:visited {
    text-decoration: none;
  }

  div.photo-title a, div.photo-title a:active, div.photo-title a:hover, div=
.photo-title a:visited {
    text-decoration: none;
  }

  div#ygrp-mlmsg #ygrp-msg p a span.yshortcuts {
    font-family: Verdana;
    font-size: 10px;
    font-weight: normal;
  }

  .green {
    color: #628c2a;
  }

  .MsoNormal {
    margin: 0 0 0 0;
  }

  o {
    font-size: 0;
  }

  #photos div {
    float: left;
    width: 72px;
  }

  #photos div div {
    border: 1px solid #666666;
    height: 62px;
    overflow: hidden;
    width: 62px;
  }

  #photos div label {
    color: #666666;
    font-size: 10px;
    overflow: hidden;
    text-align: center;
    white-space: nowrap;
    width: 64px;
  }

  #reco-category {
    font-size: 77%;
  }

  #reco-desc {
    font-size: 77%;
  }

  .replbq {
    margin: 4px;
  }

  #ygrp-actbar div a:first-child {
   /* border-right: 0px solid #000;*/
    margin-right: 2px;
    padding-right: 5px;
  }

  #ygrp-mlmsg {
    font-size: 13px;
    font-family: Arial, helvetica,clean, sans-serif;
    *font-size: small;
    *font: x-small;
  }

  #ygrp-mlmsg table {
    font-size: inherit;
    font: 100%;
  }

  #ygrp-mlmsg select, input, textarea {
    font: 99% Arial, Helvetica, clean, sans-serif;
  }

  #ygrp-mlmsg pre, code {
    font:115% monospace;
    *font-size:100%;
  }

  #ygrp-mlmsg * {
    line-height: 1.22em;
  }

  #ygrp-mlmsg #logo {
    padding-bottom: 10px;
  }


  #ygrp-msg p a {
    font-family: Verdana;
  }

  #ygrp-msg p#attach-count span {
    color: #1E66AE;
    font-weight: 700;
  }

  #ygrp-reco #reco-head {
    color: #ff7900;
    font-weight: 700;
  }

  #ygrp-reco {
    margin-bottom: 20px;
    padding: 0px;
  }

  #ygrp-sponsor #ov li a {
    font-size: 130%;
    text-decoration: none;
  }

  #ygrp-sponsor #ov li {
    font-size: 77%;
    list-style-type: square;
    padding: 6px 0;
  }=20

  #ygrp-sponsor #ov ul {
    margin: 0;
    padding: 0 0 0 8px;
  }

  #ygrp-text {
    font-family: Georgia;
  }

  #ygrp-text p {
    margin: 0 0 1em 0;
  }

  #ygrp-text tt {
    font-size: 120%;
  }

  #ygrp-vital ul li:last-child {
    border-right: none !important;=20
  }=20
  -->
  </style>
</head>

<!--~-|**|PrettyHtmlEnd|**|-~-->
</html>
<!-- end group email -->


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