A Threshold Homomorphic Blockchain Architecture for Secure and Scalable IoT Sensor Data Aggregation

We present Φ-PHE-BC, an authenticated weighted Paillier aggregation architecture with threshold recovery and a Hyperledger Fabric 2.5.16 implementation. Signatures bind integrity-sensitive sensor fields and ledger-backed nonces prevent replay. The single-host testbed uses two peer organizations and one Raft orderer, with three-of-five recovery in local off-chain shared objects. Twenty fresh-key functional runs recovered the expected aggregate and rejected 200 malformed-input evaluations. A separate 20-run campaign measured preparation of four readings through verified recovery at 4566.48±18.33 ms, excluding dealer setup and configuration commitment. A randomized matched comparison used 20 trials per mode and offered rate, with 16 records per transaction. At 50, 100, and 150 offered transactions/s, encrypted processing achieved 49.37±0.14, 95.36±5.55, and 93.09±11.57 valid transactions/s including drain; authenticated plaintext achieved 49.97±0.01, 99.89±0.03, and 149.36±1.18, respectively. These mean and sample-SD results quantify processing and representation overhead under shared-host conditions; plaintext does not provide equivalent confidentiality. Separate load and block-cut studies document backlog and generator drops. Graph connectivity, threshold recovery and Raft ordering retain distinct assumptions. Distributed-holder fault recovery, peer-count scaling, and a confidentiality-equivalent comparator remain unevaluated.