Research On Public Key Encryption With Keyword Search

The public key encryption with keyword Search (PEKS) scheme, proposedby Boneh, Crescenzo, Ostrovsky and Persiano, enables one to search forencrypted keywords without compromising the security of the original data.PEKS schemes can be widely used and deployed in many practicalapplications. An interesting application of PEKS is intelligent email routing.PEKS provides a mechanism that enables Receiver to provide the gatewaywith the ability to test whether “urgent” is a keyword in the original email,but additionally, the gateway should learn nothing else about the email itself.Recent years, public key encryption with keyword search system, due to itsunique advantages, has been extensive researched and applied. But in publickey encryption with keyword search system, there are still manyshortcomings and imperfections. Many open problems remain. Thus, wefirstly study the security problem like secure channel free, trapdoorrevocation, and keyword guessing attack in public key encryption withkeyword search itself. Secondly, we study the combination of PEKS andPKE. Thirdly, we study the combination of PEKS and C-PRE. The maincontributions of this research are as follows.Firstly, in the public key encryption with keyword search itself, we presentan efficient and secure channel free public key encryption with keywordsearch scheme without random oracle. Furthermore, seeing that the securitymodel for secure channel free public key encryption with keyword searchlimits the ability of the adversary, we enhance the security model by addinga Test oracle. We also construct a new secure channel free public keyencryption with keyword search scheme secure in the enhanced securitymodel.With regard to keyword guessing attack, we define the first formal security model of PEKS which is secure channel free and secure against keywordguessing attack. Then, we present an efficient and secure PEKS schemesecure under this model. This scheme answers an open problem at SDM2006which proposed by Byun et al. on how to construct efficient PEKSsecure against keyword guessing attacks.Since it is difficult to revoke the trapdoor effectively when the receiversends out the trapdoor to the server in PEKS system, this thesis proposes asecure channel free PEKS scheme with efficient revocation.Secondly, we study the combination of PEKS and PKE. Usually, a PEKSscheme does not allow the user to decrypt the encrypted massage, and this"no-decryption" property also limits the applicability of a PEKS scheme. Soit is desired to combine the PEKS scheme with public key encryption.However, a simple combination cannot ensure the consistency andefficiency for the ciphertext. To solve the problem, this thesis presents anefficient searchable encryption scheme with decryption (PEKSD) secureunder the standard model.Thirdly, we study the combination of PEKS and C-PRE (Conditional ProxyRe-encryption). By combining C-PRE and PEKS, we propose a newcryptographic primitive called conditional proxy re-encryption withkeyword search (C-PRES). In C-PRES scheme, the proxy can search forencrypted keywords without compromising the security of the original data.Thus, we solved the interesting open problem left by Weng et al. atASIACCS2009on how to construct CCA-secure anonymous conditionalproxy re-encryption scheme.