Privacy protection in on-line shopping for electronic documents

Blind decoding schemes are proposed as tools for protecting customers' privacy in on-line shopping for electronic documents in such a way that the documents' owner has no way of knowing which documents the customers have purchased. However, most of the blind decoding schemes suffer from the oracle problem where an adversary may obtain useful information, such as the signature of a message, by interacting with the documents' owner (the oracle) using tricky requests. In this paper, a secure blind decoding scheme based on RSA scheme is proposed. Its security against one more decoding key and oracle attacks is formally proved.