Public-key Encryption with Keyword Search (PEKS) is a mechanism that allows to search by keywords on encrypted data by generating trapdoors for the desired keywords. One inherent problem in some scenario applications of PEKS is that the Trapdoor Generation Entity should be highly trusted, since she can generate trapdoors on behalf of legitimate users. In this paper, we present a new approach to solve this problem. To this end, we define and implement two primitives: threshold public key encryption with keyword search (TPEKS) and anonymous identity-based encryption with distributed Private Key Generator ((n,t)-IBE). TPEKS is an extension of public key encryption with keyword search (PEKS) in which trapdoors are generated in a distributed manner. We also provide two generic transformations: the first one transforms an anonymous IBE scheme into an anonymous (n,t)-IBE, the second one transforms an (n,t)-IBE scheme into a secure TPEKS scheme.
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