It may be argued that the introducer should not be trusted to choose a
secret to be shared by the other sites. Even in the public key scheme,
however, the introducer can create a man-in-the-middle that has the public
key of the original designee. This conundrum is tantamount to the unresolved
EQ
problem. If an agent receives a key from just one source and has no
other source of validation for that key, then the source can supply any
key and the agent must trust the source concerning the key, When there
are other ways to validate the key then the agent may be able to trust
the key more than it trusts the source. An elementary example is when the
factory
receives a space bank key from a requestor. The agent (factory here) consults
a previously held
bank
transformer concerning the validity of the proffered bank key. Subsequently
the agent can count on bank properties by virtue of the response from the
transformer. The key equality primitive
(DISCRIM)
is the conceptual foundation for such validation in Keykos.