VA-DAR: A PQC-Ready, Vendor-Agnostic Deterministic Artifact Resolution for Serverless, Enumeration-Resistant Wallet Recovery

TL;DR

VA-DAR is a privacy-preserving, post-quantum secure protocol for serverless wallet recovery that enables cross-device access using only an identifier and passphrase, while resisting enumeration attacks.

Contribution

It introduces a vendor-agnostic, post-quantum secure discovery and recovery layer over ACE-GF, with formal security proofs and practical recovery mechanisms.

Findings

Provides practical cross-device recovery with minimal user input.

Ensures computational resistance to enumeration attacks.

Proves security properties under standard cryptographic assumptions.

Abstract

Serverless wallet recovery must balance portability, usability, and privacy. Public registries enable decentralized lookup but naive identifier hashing leaks membership through enumeration. We present VA-DAR, a keyed-discovery protocol for ACE-GF-based wallets that use device-bound passkeys for day-to-day local unlock while supporting cross-device recovery using only a user-provided identifier (e.g., email) and a single recovery passphrase. As a discovery-and-recovery layer over ACE-GF, VA-DAR inherits ACE-GF's context-isolated, algorithm-agile derivation substrate, enabling non-disruptive migration to post-quantum algorithms at the identity layer. The design introduces a decentralized discovery-and-recovery layer that maps a privacy-preserving discovery identifier to an immutable content identifier of a backup sealed artifact stored on a decentralized storage network. Concretely, a user derives passphrase-rooted key material with a memory-hard KDF, domain-separates keys for artifact sealing and discovery indexing, and publishes a registry record keyed by a passphrase-derived discovery identifier. VA-DAR provides: (i) practical cross-device recovery using only identifier and passphrase, (ii) computational resistance to public-directory enumeration, (iii) integrity of discovery mappings via owner authorization, and (iv) rollback/tamper detection via monotonic versioning and artifact commitments. We define three sealed artifact roles, two update-authorization options, and three protocol flows (registration, recovery, update). We formalize security goals via cryptographic games and prove, under standard assumptions, that VA-DAR meets these goals while remaining vendor-agnostic and chain-agnostic. End-to-end post-quantum deployment additionally requires a PQ-secure instantiation of registry authorization.