基于比特币的私有信息检索支付协议

私有信息检索（PIR）是一种密码学工具，使用户能够从远程数据库服务器中获取信息，而不会让服务器知道用户获取了什么信息。PIR方案基本上由两种类型组成，即信息论私有信息检索（Information Theoretic PIR，IT-PIR）和计算性私有信息检索（Computational PIR，C-PIR）。IT-PIR方案要求服务器之间不共谋。一旦服务器共谋，就无法保证用户的隐私。共谋问题一直以来都没有一个比较好的解决办法。比特币和区块链的出现为解决公平和信任的问题提供了一种新方法。在本文中，我们创新地使用区块链来处理IT-PIR中的共谋问题，提出了一种基于比特币的PIR支付协议。在此支付协议中，客户通过比特币交易支付服务费。我们通过比特币脚本控制交易兑现的条件，使得如果服务方相互串通，则使服务方受到利益损失。通过这种方式，该支付协议可以在一定程度上降低共谋的可能性。

Bitcoin-based Payment Protocol for Private Information Retrieval

Private information retrieval(PIR) is a cryptographic primitive that enables the client to get information from a remote database server without letting the server know what information the client fetched. PIR schemes basically consist of two types, information-theoretic PIR(IT-PIR) and computational PIR(C-PIR). IT-PIR schemes require that the servers are non-cooperating. Once the servers collude, the client''s privacy cannot be guaranteed. The emergence of Bitcoin and blockchain provides a new way to solve the problem of trust. In this paper, we innovatively use blockchain to tackle the colluding problem of IT-PIR, propose a PIR payment scheme based on Bitcoin. In this payment scheme, the client pays the service fee by Bitcoin transactions. We control the conditions of the redemption of the transaction, makes the servers suffer a loss of profits if they collude with each other. In this way, this payment protocol can decrease the probability of colluding to some extent.