Re: [bitcoin-dev] Implementing Covenants with OP_CHECKSIGFROMSTACKVERIFY

["Russell O'Connor" <roconnor@blockstream.io>]

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Right.  There are minor trade-offs to be made with regards to that design
point of OP_CHECKSIGFROMSTACKVERIFY.  Fortunately this covenant
construction isn't sensitive to that choice and can be made to work with
either implementation of OP_CHECKSIGFROMSTACKVERIFY.

On Wed, Nov 2, 2016 at 11:35 PM, Johnson Lau <jl2012@xbt.hk> wrote:

> Interesting. I have implemented OP_CHECKSIGFROMSTACKVERIFY in a different
> way from the Elements. Instead of hashing the data on stack, I directly put
> the 32 byte hash to the stack. This should be more flexible as not every
> system are using double-SHA256
>
> https://github.com/jl2012/bitcoin/commits/mast_v3_master
>
>
> On 3 Nov 2016, at 01:30, Russell O'Connor via bitcoin-dev <
> bitcoin-dev@lists.linuxfoundation.org> wrote:
>
> Hi all,
>
> It is possible to implement covenants using two script extensions: OP_CAT
> and OP_CHECKSIGFROMSTACKVERIFY.  Both of these op codes are already
> available in the Elements Alpha sidechain, so it is possible to construct
> covenants in Elements Alpha today.  I have detailed how the construction
> works in a blog post at <https://blockstream.com/2016/
> 11/02/covenants-in-elements-alpha.html>.  As an example, I've constructed
> scripts for the Moeser-Eyal-Sirer vault.
>
> I'm interested in collecting and implementing other useful covenants, so
> if people have ideas, please post them.
>
> If there are any questions, I'd be happy to answer.
>
> --
> Russell O'Connor
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>
>

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