Asymmetric $X$-Secure $T$-Private Information Retrieval: More Databases is Not Always Better. (arXiv:2305.05649v1 [cs.IT])

We consider a special case of $X$-secure $T$-private information retrieval
(XSTPIR), where the security requirement is \emph{asymmetric} due to possible
missing communication links between the $N$ databases considered in the system.
We define the problem with a communication matrix that indicates all possible
communications among the databases, and propose a database grouping mechanism
that collects subsets of databases in an optimal manner, followed by a
group-based PIR scheme to perform asymmetric XSTPIR with the goal of maximizing
the communication rate …

case communication communications databases information links matrix missing private problem security special system