Cross-Chain Synchronization and Privacy-Preserving Threshold Authorization for Blockchain-Based Mobile Payments

Abstract

Blockchain-based mobile payments require settlement controls that remain safe when value crosses heterogeneous ledgers and release depends on multiple approvers. This study develops and evaluates a fail-closed settlement pipeline in which cross-chain admission precedes fund release. The cross-chain layer combines a paper-specific hash-time-locked exchange composition (HFASE), schema normalization and HMAC-SHA-256 integrity (FSTF-DO), a three-phase Byzantine commit with view-change using the intersection quorum q = ⌈(n+f+1)/2⌉, and a past-context Bi-LSTM sequence check paired with deterministic state-machine rules. The authorization layer combines Paillier-based private threshold counting, Merkle-based factor binding, and a Bi-3DQRNN-CNN behavioural gate. We provide proof sketches for atomicity, quorum safety and bounded liveness, and execute controlled adversarial tests and component ablations. A fixed 2f+1 single-round quorum violated safety in 15 of 20 tested configurations under an equivocating leader; the intersection quorum with view-change produced no observed safety violations in the same test matrix. In controlled streams, deterministic rules achieved F1 = 0.77, while rules combined with the past-context Bi-LSTM achieved recall = 0.84. An in-process five-stage execution driven by 1,000 real Elliptic transaction records committed 918 records with a mean end-to-end processing latency of 45.39 ms. The measured 57.4 ms value is a separate conditional local 3-of-5 counting-only predecessor and is not an end-to-end result. The evidence supports a prototype-level security architecture; live heterogeneous-chain deployment, asynchronous-network evaluation, handset measurements, and a standalone public-data evaluation of the stage-5 behavioural gate remain open.