Designated Server Certificateless Deniably Authenticated Encryption With Keyword Search

In email system, the cryptography technology has been used to defend email secrets, so it is important to search specific encrypted emails on cloud sever without local decryption. The Public key encryption with keyword search (PEKS) might is a suitable way to perform the email ciphertext search. However, most existing PEKS schemes cannot protect the identity privacy of data sender. Deniably authenticated encryption (DAE) technique allows the data sender to deny his/her involvement after the communication. Moreover, the receiver can verify the authenticity of ciphertext in DAE, which assures the identity privacy of data sender. In this paper, so as to solve the above shortages in existing PEKS schemes, we introduce an original scheme called designated server certificateless deniably authenticated encryption with keyword search (dCLDAEKS), where leverages the techniques of DAE and designated server. In dCLDAEKS, data sender authenticates the messages and simultaneously encrypt them. Meanwhile, only designated server has ability to execute search ciphertext operation for receivers. So there is no adversary including the server can launch inside or outside offline KGA. Therefore dCLDAEKS scheme can better protect the identity privacy of data sender. In addition, compared the related schemes in the literature, dCLDAEKS scheme perform less efficient in some procedure, but it can against inside KGA and better protect the sender's identity privacy.