No abstract

As the further extension of the multi-receiver signcryption, the multi-message and multireceiver signcryption allows a sender to simultaneously signcrypt different messages for different receivers in only one logic operation, which makes it more flexible than the traditional multi-receiver signcryption in which only the same and unique message can be sent to all authorized receivers. The existing multimessage and multi-receiver signcryption schemes are constructed based on either the identity-based cryptography or the public key infrastructure-based cryptography, and thus, they have to suffer from the key escrow problem inherent in the identity-based cryptography or the public key certificate management burden related with the public key infrastructure-based cryptography. Certificateless public key cryptography provides an idea to solve the key escrow problem and eliminate the public key certificate management burden and has been applied to many cryptographic algorithms. In this paper, to avoid the above problems in the existing multi-message and multi-receiver signcryption schemes, the concept of the certificateless public key cryptography was introduced into the designing of the multi-message and multi-receiver signcryption, and a certificateless multi-message and multi-receiver signcryption scheme was proposed. The proposed scheme is free from the key escrow problem and the public key certificate management burden because it is constructed based on the certificateless public key cryptography. Moreover, compared with the existing schemes, it is improved in efficiency because it does not use the bilinear pairing operations but utilizes the limited number of scalar point multiplication on elliptic curve cryptography operations. At the same time, the proposed scheme achieves receiver anonymity. INDEX TERMS Certificateless public key cryptography, elliptic curve cryptography, multi-message and multi-receiver signcryption, receiver anonymity. I. INTRODUCTION With the development of the Internet and communication technologies, multicast services have become more and more popular in our daily life, such as mobile crowdsensing [1] and cloud computing [2], [3]. Multi-receiver encryption/ signcryption [4], widely considered as one of most promising and efficient solutions to one-to-many secure communication, enables the sender to securely send the same message The associate editor coordinating the review of this manuscript and approving it for publication was Zhitao Guan.

The certificateless multi-receiver signcryption scheme provides the sender with the ability to send the same message to multiple authorized receivers contemporaneously, and at the same time, it can avoid the key escrow problem in the existing identity-based multi-receiver signcryption schemes, which makes it to get great attention in the field of one-to-many communication. However, in the existing certificateless multi-receiver signcryption schemes, a secure channel is essential for their key extract algorithm, which brings some troubles in practical applications. On one hand, the security of the partial private key depends on the secure channel. Once the secure channel is broken by an attacker, the user's partial private key may be leaked. On the other hand, maintaining the secure channel increases the economic cost and implementation complexity of the application systems. Motivated by these concerns, we propose a new anonymous certificateless multi-receiver signcryption scheme, in which the key generation center only utilizes a public channel to send the pseudo partial private key to the user during the key extract algorithm, and the designated user can work out the real partial private key from the pseudo partial private key while others cannot. The avoidance of the secure channel improves the security of the proposed scheme and makes the communication system much lighter. INDEX TERMS Cryptography, certificateless public key cryptography, multi-receiver signcryption, one-tomany communication, key escrow problem, receiver anonymity.