  We consider the problem of privacy in direct communications, showing how
quantum mechanics can be useful to guarantee a certain level of
confidentiality. In particular, we review a continuous variable approach
recently proposed by us [S. Pirandola et al., Europhys. Lett. 84, 20013
(2008)]. Here, we analyze the degree of privacy of this technique against a
broader class of attacks, which includes non-Gaussian eavesdropping.
