  We analyze the security of two multipartite quantum key distribution (QKD)
protocols, specifically we introduce an $N$-partite version of the BB84
protocol and we discuss the $N$-partite six-state protocol proposed in
arXiv:1612.05585v2. The security analysis proceeds from the generalization of
known results in bipartite QKD to the multipartite scenario, and takes into
account finite resources. In this context we derive a computable expression for
the achievable key rate of both protocols by employing the best-known
strategies: the uncertainty relation and the postselection technique. We
compare the performances of the two protocols both for finite resources and
infinitely many signals.
