• Sergey Pepyakin's avatar
    pvf-precheck: Add `sign` in subsystem-util (#4407) · e4580d09
    Sergey Pepyakin authored
    Right now, most of operations that sign stuff in polkadot protocol are
    handled by a very convenient tool - `Signed`. However `Signed` assumes
    that whatever is signed is anchored to some `parent_hash` which works
    for most cases, but does not work for others.
    One instance of such a case is pre-checking (#3211). There validators
    submit signed votes on-chain. A vote is valid for the entire session. If
    we were to use `Signed` we would have to root a vote in some block of
    that session and during vote verification check that this block is
    indeed within the session. This is especially annoying since we agreed
    to use unsigned extrinsics to submit votes and we need to make the
    unsigned extrinsic validation as slim as possible.
    (FWIW, the definition of a pre-checking vote can be seen in the next
    diff in the stack)
    That's the reason why we opted-out from using `Signed` for pre-checking
    and decided to go with the manual signing approach. Almost every piece
    of machinery is in place except for signing which is presented in this