0xPass: A Secure Protocol for Universal Cross-Chain Accounts

Universal accounts allow users to manage assets and execute operations across heterogeneous blockchain ecosystems through a single interface, but they introduce security and trust challenges involving authentication, authorization, transaction signing, key custody, recovery, and decentralization. This paper presents 0xPass, a modular protocol architecture for universal cross-chain accounts. 0xPass separates request orchestration, transaction solving, and transaction signing into interoperable layers. User-approved requests are bound to authenticated identities and authorized across layers, while threshold signatures prevent any single transaction node from holding a complete signing key. The design also supports constrained authorization delegation, transaction policies, account recovery, distributed key management, and auditable communication among independently operated sub-networks. We describe a staged deployment path from a centrally operated service to a permissioned network and ultimately to a permissionless network with third-party modules, collateral-backed onboarding, and rotating key-management committees. The resulting architecture provides a practical framework for extending cross-chain account functionality while progressively reducing centralized trust and preserving user control over transaction authorization.