There was a protocol someone mentioned a while back called Sabu that had
the same goals. As i recall, it had some pretty promising constructs, but
would have a critical vulnerability that could be exploited by miners. This
is the write up:

https://raymo-49157.medium.com/time-to-boost-bitcoin-circulation-million-transactions-per-second-and-privacy-1eef8568d180

Perhaps some of the techniques there could be combined with your ideas to
get closer to a solution.

On Mon, Jan 24, 2022, 08:51 AdamISZ via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> Hello list,
>
> I took the time to write up this rather out-there idea:
>
> Imagine you wanted to send a coin just like email, i.e. just transfer data
> to the counterparty.
>
> Clearly this is in general entirely impossible; but with what restrictions
> and assumptions could you create a toy version of it?
>
> See this gist for a detailed build up of the idea:
>
> https://gist.github.com/AdamISZ/b462838cbc8cc06aae0c15610502e4da
>
> Basically: using signature adaptors and CTV or a similar covenant, you
> could create a fully trustless transfer of control of a utxo from one party
> to another with no interaction with the rest of the group, at the time of
> transfer (modulo of course lots and lots of one-time setup).
>
> The limitations are extreme and as you'd imagine. In the gist I feel like
> I got round one of them, but not the others.
>
> (I very briefly mention comparison to e.g. statechains or payment pools;
> they are making other tradeoffs against the 'digital cash' type of goal.
> There is no claim that this 'pathcoin' idea is even viable yet, let alone
> better than those ideas).
>
> Publishing this because I feel like it's the kind of thing imaginative
> minds like the ones here, may be able to develop further. Possibly!
>
>
> waxwing / AdamISZ
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