Helper for signature verification.
Retrieves the TPKs containing the specified keys.
Conveys the result of a signature verification.
This is called after the last signature has been verified. This is the place to implement your verification policy. Check that the required number of signatures or notarizations were confirmed as valid.
The argument is a vector, with
sigs being the vector of
signatures over the data,
vec being notarizations over
signatures of level 0, and the data, and so on.
This callback is only called before all data is returned.
That is, once
io::Read returns EOF, this callback will not
be called again. As such, any error returned by this function
will abort reading, and the error will be propagated via the