  This paper presents a hybrid blockchain-edge architecture for managing
Electronic Health Records (EHRs) with attribute-based cryptographic mechanisms.
The architecture introduces a novel attribute-based signature aggregation
(ABSA) scheme and multi-authority attribute-based encryption (MA-ABE)
integrated with Paillier homomorphic encryption (HE) to protect patients'
anonymity and safeguard their EHRs. All the EHR activities and access control
events are recorded permanently as blockchain transactions. We develop the ABSA
module on Hyperledger Ursa cryptography library, MA-ABE module on OpenABE
toolset, and blockchain network on Hyperledger Fabric. We measure the execution
time of ABSA's signing and verification functions, MA-ABE with different access
policies and homomorphic encryption schemes, and compare the results with other
existing blockchain-based EHR systems. We validate the access activities and
authentication events recorded in blockchain transactions and evaluate the
transaction throughput and latency using Hyperledger Caliper. The results show
that the performance meets real-world scenarios' requirements while
safeguarding EHR and is robust against unauthorized retrievals.
