Modelling confidential vs explicit transaction outputs

[thomaseizinger]

As mentioned here, this is a dedicated issue for discussing our attempt at re-modelling confidential and explicit transactions.

We assumed that a TxOut can either confidential or explicit - i.e. both the asset and the value are either confidential or explicit - but this turned out to not be true.

To be honest, I don't fully understand what a "pre-asset" confidential transaction is? Can I read up on this somewhere to get an overview of what the usecases are and what they look like on-chain?

[thomaseizinger]

After having worked with the model in our fork for a while, the most useful APIs turned out to be the conversion functions into_explicit and into_confidential on TxOut: https://github.com/comit-network/waves/blob/b4a4dfa746784429f4711e72928f156bc191702d/elements-fun/src/transaction.rs#L709-L735

For these APIs to exist, we would not necessarily have had to do all the re-modelling that we did so I am thinking of contributing such functions back to rust-elements so we don't have to maintain our fork :)

That should combine the best of both worlds:

• being able to parse all kinds of combinations of explicit vs confidential information
• having better support from the type system in deal with fully explicit vs fully confidential TxOuts

[thomaseizinger]

Resolved in #78 🎉