📝 SummarXiv

Abstract

We propose a secure, stateless and composable transaction scheme to establish delivery-versus-payment (DvP) across two blockchains without relying on time-locks, centralized escrow, or stateful intermediaries. The method minimizes coordination overhead and removes race conditions via a stateless decryption oracle that conditionally releases cryptographic keys. Specifically, the scheme requires: - a decryption oracle service - either centralized or using threshold decryption - that decrypts transaction-specific encrypted messages, and - a "payment contract" on the payment chain that executes conditional payments via transferAndDecrypt(uint256 id, address from, address to, string keyEncryptedSuccess, string keyEncryptedFail) and emits the appropriate key, depending on transaction outcome. The decrypted key then deterministically enables follow-up transactions - such as asset delivery or cancellation - on a separate blockchain. The protocol is lightweight and compatible with existing blockchain infrastructure (e.g., Ethereum), and avoids timeouts or pre-defined orderings. Our approach improves atomic cross-chain settlement and can serve as a blueprint for decentralized inter-chain financial markets.