1) Perhaps rather then being a knob you frob, the levels are an indicator.
The lower the number, the more trust you can have as to the authenticity of
the message.
Another possibility would be to have a list of
"pattern" - level
pairs that you configure your reader with.. if "pattern" matches the
DN of a sender (or PCA or CA, for that matter), that sets the level at
which the message is obviously flagged as of questionable
authenticity. The "real" level should always be available, of course,
but this allows the reader to make exceptions for (for example)
certain "far-away" CA's they may not always have a current CRL for,
while not reducing the trust they can put in nearby CA's.
- Bill