A Decentralized Behavioral Trust Framework Across Mobile Networks

Mobile communication channels have become a major target for large-scale and adaptive fraud, including impersonation, phishing, and unsolicited calls. Existing caller-verification frameworks depend on centralized heuristics and static credentials that fail to reflect behavioral trust or protect users in real time. This paper presents BTID (Behavioral Trust for Identity Decentralization) - a decentralized, privacy-preserving identity framework that derives caller reputation from verified behavioral feedback. BTID integrates Decentralized Identifiers (DIDs) and Verifiable Credentials (VCs) with a lightweight zero-knowledge-proof mechanism, enabling callers to prove that their behavioral reputation meets a callee's trust threshold without revealing their actual score or personal data. Each post-call rating is recorded as a cryptographic commitment and aggregated through a pairwise Sybil-resistant reputation model governed by exponential decay (λ = 0.0039, six-month half-life). A reference prototype demonstrates that the protocol is implementable and logically sound even under high-cost and high-latency conditions on public ledgers. On modern lightweight networks such as Algorand or IOTA, the same architecture can achieve sub-second verification and near-zero cost. Beyond its technical contribution, BTID also reframes the role of the blockchain itself. Rather than treating decentralization as an ideological end, this work demonstrates that a tamper-proof and privacy-preserving public ledger can serve as a shared, universal database accessible to all participants and not as a silo controlled by industrial conglomerates. In doing so, BTID shows that the blockchain can function as a neutral trust infrastructure capable of addressing a real and universal problem in mobile communication: establishing behavioral trust without sacrificing privacy.