Efficient and provably secure random oracle-free adaptive identity-based encryption with short-signature scheme

Identity-based encryption (IBE) is one of the important public key encryption techniques where not only the identity of the receiver is used for secure and efficient encryption, but it also has several merits over other traditional public-key ones. However, two main disadvantages of many such IBE-based systems are the requirement of a large number of public parameters and different random oracle operations, where it is known that a random oracle due to improper implementation is vulnerable under chosen ciphertext attack. This paper designs an efficient IBE scheme (ROFIBE) with recipient anonymity, reduction in public parameters and random oracle-free operation. The scheme is developed based on a proposed hard problem, named as decisional extended bilinear Diffie-Hellman assumption (DEBDH) and on analysis it is found to be secured under standard security model. In addition, a new short-signature scheme based on the proposed IBE is developed under the difficulty of solving proposed q-extended bilinear strong Diffie-Hellman assumption (q-EBSDH). As performance analysis, we compare both the proposed schemes with other existing related ones and find that our schemes are computationally and communicationally efficient and effectively usable in real life applications. Copyright (C) 2016 John Wiley & Sons, Ltd.