  We propose a "cryptographic" interpretation for the propositional connectives
of primal infon logic introduced by Y. Gurevich and I. Neeman and prove the
corresponding soundness and completeness results. Primal implication
$\imp{\varphi}{\psi}$ corresponds to the encryption of $\psi$ with a secret key
$\varphi$, primal disjunction $\vp{\varphi}{\psi}$ is a group key and $\bot$
reflects some backdoor constructions such as full superuser permissions or a
universal decryption key. For the logic of $\bot$ as a universal key (it was
never considered before) we prove that the derivability problem has linear time
complexity. We also show that the universal key can be emulated using primal
disjunction.
