Before a fair exchange takes place, there is typically an advertisement phase with the goal of increasing the appeal of possessing a digital asset while keeping it sufficiently hidden. In this work, we give a definition that explicitly combines a fair-exchange protocol with a prior advertising phase. Then, we construct such a fair exchange protocol with aids using zk-SNARKs and relying on mainstream decentralized platforms (i.e., a blockchain with smart contracts like Ethereum and a decentralized storage system like IPFS). Experimental results confirm the practical relevance of our decentralized approach, paving the road towards building decentralized marketplaces where users can, even anonymously, and without direct off-chain communications, effectively advertise and exchange their digital assets as part of a system of enhanced NFTs.

翻译：在公平交换发生之前，通常存在一个广告阶段，其目标是在保持数字资产充分隐蔽的同时，增加拥有该资产的吸引力。在这项工作中，我们提出了一个明确定义，将公平交换协议与先前的广告阶段相结合。随后，我们利用zk-SNARKs并依托主流去中心化平台（即具备智能合约的区块链如以太坊，以及去中心化存储系统如IPFS），构建了这样一种辅助性的公平交换协议。实验结果证实了我们这种去中心化方法的实际可行性，为构建去中心化市场铺平了道路。在这种市场中，用户即使匿名且无需直接的链下通信，也能有效宣传并交换其数字资产，作为增强型NFT系统的一部分。