Quantum-Safe Aadhaar: A Decentralized Multi-Chain KYC System Using Ring-LWE DIDs using did:pqie

Abstract

Abstract We present a post-quantum, cross-chain Aadhaar e-KYC system that decouples citizen identity from any single blockchain while preserving full quantum resistance. The system introduces did:pqie — a new W3C Decentralized Identifier (DID) method grounded in Ring Learning With Errors (Ring-LWE) cryptography (n = 512, q = 24593, = 4.0) — and demonstrates its application across three heterogeneous ledgers: Hyperledger Indy, Ethereum, and Polkadot. Upon government approval of a KYC submission, the system automatically issues a W3C Verifiable Credential anchored simultaneously on all three chains. Service access is gated by a Zero-Knowledge Proof (ZKP)-based token that proves credential validity without revealing any personally identifiable information. Selective disclosure via Merkle commitments allows citizens to reveal only required attributes. Our evaluation shows that the entire system — DID generation, multi-chain VC issuance, and ZKP token generation — operates within practical latency bounds while providing 256-bit post-quantum security. The did:pqie method has been submitted for registration with the W3C DID Methods Registry.