  We analyze the information an attacker can obtain on the numbers generated by
a user by measurements on a subsystem of a system consisting of two entangled
two-level systems. The attacker and the user make measurements on their
respective subsystems, only. Already the knowledge of the density matrix of the
subsystem of the user completely determines the upper bound on the information
accessible to the attacker. We compare and contrast this information to the
appropriate bounds provided by quantum state discrimination.
