Composable Conditions

Hi list,

During one of the recent community group calls we promised that we would
work on a better nomenclature for crypto-conditions.

The main criticism we heard was that it seemed like it was called
crypto-conditions based on a very narrow use case (triggering events based
on signatures) in five-bells-ledger and that using them for multi-sig was
going to be a more common use case.

However, one person also commented that hashlocks aren't really signatures.
(We've called them zero-bit signatures before, but that's like calling a
road a "zero-river bridge".)

I've discussed the terminology with Evan and here is what we propose:

Composable Conditions are a standard for cryptographic one-way functions
and ways to compose them.

The idea here is that "condition" is actually broader than "signature". A
signature verification algorithm is a function which returns a boolean:
valid/invalid. A hashlock is also a function which returns a boolean:
valid/invalid. In the future we may add a scriptable condition, but it
would still return true or false. The general term for a thing that returns
true or false is a "condition".

Once you think about the idea of a "condition", you can also understand the
use cases for this standard. Conditions can be triggers for events, but
they can also be used for authentication ("accept any command that meets
this condition".)

The term "condition" also neatly expresses what we think is not in scope:
Our spec specifically does not allow you to perform computation (returning
values other than true or false.)

Aside from the fact that it abstracts the condition type, the other
significant feature of the standard is that it provides condition types
which are a composition of other conditions.

That's why we propose "Composable Conditions" as the new name. Please let
us know your feedback in this thread!

- Stefan