class key_ring :?uplink:#key_handler -> ?no_invalidation:bool -> unit ->object..end
The key_ring is a cache for keys. The optional uplink handler
is invoked when no matching key is found in the cache. The uplink
is intended for interactively asking the user for a password.
If no_invalidation is set, keys are never invalidated (removed after
they did not work)
method clear : unit -> unitDeletes all keys from this key ring
method add_key : key -> unitAdds a key to the ring
method keys : key listList of all known keys
