Deposit-Escrow EV Charging on Avalanche with zk-SNARK Billing Proofs: Prototype Scope and Security Limits

Abstract

Electric-vehicle (EV) charging workflows expose billing and session information through centralized services or transparent ledgers. This study integrates deposit escrow, a Groth16 billing-arithmetic proof, and settlement on the Avalanche Fuji testnet. Its contribution is a proof-of-concept workflow linking authorization, payment, refund, and timeout handling, together with an analysis of the boundary between the implemented proof and a proposed station-authenticated protocol. Across five runs per setting, mean deposit and settlement confirmation times are 1.8 s and 2.1 s, respectively; proof generation averages 0.21 s on a desktop PC; and settlement consumes approximately 320,000 gas. These descriptive results apply to a simplified circuit that checks billing arithmetic with a placeholder binding. Station signatures are checked only by the off-chain harness, so station-authenticated billing and resistance to substituted energy witnesses remain unvalidated. Normal settlement provides meter-field omission, not consumption confidentiality: under the exact public linear tariff, energy E is recoverable from public payment C and positive tariff p as E = C/p. The results support feasibility of the escrow-and-arithmetic-proof workflow; authenticated witness binding, complete reproducibility artifacts, and stronger experimental validation remain prerequisites for a secure deployment.