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 <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 > <mailto: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 > <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 > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > <mailto:bitcoin-dev@lists.linuxfoundation.org> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
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