Anonymous Certificateless Multi-Receiver Signcryption Scheme Without Secure Channel

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.