* [bitcoin-dev] Ivy: a higher-level language targeting Bitcoin Script @ 2017-12-18 20:32 Daniel Robinson 2018-01-14 22:41 ` Matt Corallo 0 siblings, 1 reply; 3+ messages in thread From: Daniel Robinson @ 2017-12-18 20:32 UTC (permalink / raw) To: Bitcoin Protocol Discussion [-- Attachment #1: Type: text/plain, Size: 1012 bytes --] Today, we’re releasing Ivy, a prototype higher-level language and development environment for creating custom Bitcoin Script programs. You can see the full announcement here <https://blog.chain.com/ivy-for-bitcoin-a-smart-contract-language-that-compiles-to-bitcoin-script-bec06377141a>, or check out the docs <https://docs.ivy-lang.org/bitcoin/> and source code <https://github.com/ivy-lang/ivy-bitcoin>. Ivy is a simple smart contract language that can compile to Bitcoin Script. It aims to improve on the useability of Bitcoin Script by adding affordances like named variables and clauses, static (and domain-specific) types, and familiar syntax for function calls. To try out Ivy, you can use the Ivy Playground for Bitcoin <https://ivy-lang.org/bitcoin/>, which allows you to create and test simulated contracts in a sandboxed environment. This is prototype software intended for educational and research purposes only. Please don't try to use Ivy to control real or testnet Bitcoins. [-- Attachment #2: Type: text/html, Size: 1320 bytes --] ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [bitcoin-dev] Ivy: a higher-level language targeting Bitcoin Script 2017-12-18 20:32 [bitcoin-dev] Ivy: a higher-level language targeting Bitcoin Script Daniel Robinson @ 2018-01-14 22:41 ` Matt Corallo 2018-01-15 22:39 ` Daniel Robinson 0 siblings, 1 reply; 3+ messages in thread From: Matt Corallo @ 2018-01-14 22:41 UTC (permalink / raw) To: Daniel Robinson, Bitcoin Protocol Discussion, Daniel Robinson via bitcoin-dev [-- Attachment #1: Type: text/plain, Size: 1502 bytes --] I'm curious if you've considered adding some form of compiler-time enforcement to prevent witness malleability? With that, Ivy could help to resolve for it's users one of the things that can make Bitcoin scripts more complicated to write, instead of simply type-checking and providing a high-level language mapped 1-to-1 with Bitcoin script. On December 18, 2017 8:32:17 PM UTC, Daniel Robinson via bitcoin-dev <bitcoin-dev@lists•linuxfoundation.org> wrote: >Today, we’re releasing Ivy, a prototype higher-level language and >development environment for creating custom Bitcoin Script programs. >You >can see the full announcement here ><https://blog.chain.com/ivy-for-bitcoin-a-smart-contract-language-that-compiles-to-bitcoin-script-bec06377141a>, >or check out the docs <https://docs.ivy-lang.org/bitcoin/> and source >code ><https://github.com/ivy-lang/ivy-bitcoin>. > >Ivy is a simple smart contract language that can compile to Bitcoin >Script. >It aims to improve on the useability of Bitcoin Script by adding >affordances like named variables and clauses, static (and >domain-specific) >types, and familiar syntax for function calls. > >To try out Ivy, you can use the Ivy Playground for Bitcoin ><https://ivy-lang.org/bitcoin/>, which allows you to create and test >simulated contracts in a sandboxed environment. > >This is prototype software intended for educational and research >purposes >only. Please don't try to use Ivy to control real or testnet Bitcoins. [-- Attachment #2: Type: text/html, Size: 2020 bytes --] ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [bitcoin-dev] Ivy: a higher-level language targeting Bitcoin Script 2018-01-14 22:41 ` Matt Corallo @ 2018-01-15 22:39 ` Daniel Robinson 0 siblings, 0 replies; 3+ messages in thread From: Daniel Robinson @ 2018-01-15 22:39 UTC (permalink / raw) To: Matt Corallo; +Cc: Daniel Robinson via bitcoin-dev [-- Attachment #1: Type: text/plain, Size: 2943 bytes --] Hi Matt, Thanks for raising this. Since the compiler only produces SegWit addresses, I hadn't worried at all about malleability, but as you pointed out out-of-band, malleability in the length of an argument can allow an attacker to deflate the feerate of a transaction. There was in fact a minor witness malleability problem with how the compiler was handling clause selection. It's now been fixed in version 0.0.7 of the compiler. As far as I can tell (and I haven't looked all that carefully), any sensible Ivy contract won't have any witness malleability problem. (A funny exception is the RevealCollision contract, since you can length-extend the arguments to get another collision. But without a signature check, that one has a more serious transaction malleability problem anyway.) But the compiler currently doesn't prevent you from doing dumb unconstrained stuff like: ``` clause spend(a: Bytes, b: Bytes, sig: Signature) { verify a == b verify checkSig(publicKey, sig) unlock val } ``` Maybe it should, particularly since there's no reason to include a trivial condition like that anyway. But I think it would probably be about as easy (and more generally useful) to build a static analyzer that solved this problem for low-level Bitcoin Script. On Sun, Jan 14, 2018 at 5:42 PM Matt Corallo <lf-lists@mattcorallo•com> wrote: > I'm curious if you've considered adding some form of compiler-time > enforcement to prevent witness malleability? With that, Ivy could help to > resolve for it's users one of the things that can make Bitcoin scripts more > complicated to write, instead of simply type-checking and providing a > high-level language mapped 1-to-1 with Bitcoin script. > > > On December 18, 2017 8:32:17 PM UTC, Daniel Robinson via bitcoin-dev < > bitcoin-dev@lists•linuxfoundation.org> wrote: >> >> Today, we’re releasing Ivy, a prototype higher-level language and >> development environment for creating custom Bitcoin Script programs. You >> can see the full announcement here >> <https://blog.chain.com/ivy-for-bitcoin-a-smart-contract-language-that-compiles-to-bitcoin-script-bec06377141a>, >> or check out the docs <https://docs.ivy-lang.org/bitcoin/> and source >> code <https://github.com/ivy-lang/ivy-bitcoin>. >> >> Ivy is a simple smart contract language that can compile to Bitcoin >> Script. It aims to improve on the useability of Bitcoin Script by adding >> affordances like named variables and clauses, static (and domain-specific) >> types, and familiar syntax for function calls. >> >> To try out Ivy, you can use the Ivy Playground for Bitcoin >> <https://ivy-lang.org/bitcoin/>, which allows you to create and test >> simulated contracts in a sandboxed environment. >> >> This is prototype software intended for educational and research purposes >> only. Please don't try to use Ivy to control real or testnet Bitcoins. >> >> [-- Attachment #2: Type: text/html, Size: 3868 bytes --] ^ permalink raw reply [flat|nested] 3+ messages in thread
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