Kavli Affiliate: Xiang Zhang
| First 5 Authors: Zhou Li, Zhou Li, , ,
| Summary:
Motivated by federated learning (FL), secure aggregation (SA) aims to
securely compute, as efficiently as possible, the sum of a set of inputs
distributed across many users. To understand the impact of network topology,
hierarchical secure aggregation (HSA) investigated the communication and secret
key generation efficiency in a 3-layer relay network, where clusters of users
are connected to the aggregation server through an intermediate layer of
relays. Due to the pre-aggregation of the messages at the relays, HSA reduces
the communication burden on the relay-to-server links and is able to support a
large number of users. However, as the number of users increases, a practical
challenge arises from heterogeneous security requirements–for example, users
in different clusters may require varying levels of input protection. Motivated
by this, we study weakly-secure HSA (WS-HSA) with collusion resilience, where
instead of protecting all the inputs from any set of colluding users, only the
inputs belonging to a predefined collection of user groups (referred to as
security input sets) need to be protected against another predefined collection
of user groups (referred to as collusion sets). Since the security input sets
and collusion sets can be arbitrarily defined, our formulation offers a
flexible framework for addressing heterogeneous security requirements in HSA.
We characterize the optimal total key rate, i.e., the total number of
independent key symbols required to ensure both server and relay security, for
a broad range of parameter configurations. For the remaining cases, we
establish lower and upper bounds on the optimal key rate, providing
constant-factor gap optimality guarantees.
| Search Query: ArXiv Query: search_query=au:”Xiang Zhang”&id_list=&start=0&max_results=3