  Anonymous Veto (AV) and Dining cryptographers (DC) are two basic primitives
for the cryptographic problems where the main aim is to hide the identity of
the senders of the messages. These can be achieved by classical methods where
the security is based either on computational hardness or on shared private
keys. In this regard, we present a secure quantum protocol for both DC and AV
by exploiting the GHZ correlations. We first solve a generalized version of the
DC problem with the help of multiparty GHZ state. This allow us to provide a
secure quantum protocol for the AV. Securities for both the protocols rely on
some novel and fundamental features of GHZ correlations related to quantum
nonlocality.
