Research Of Multi-receiver Signcryption Based On ECC Without The Key Escrow Problem

With development of network technology and its applications,multi-receiver encryption scheme has become more and more important in one-to-many communication.Multi-receiver encryption technology only need one operation to send the same message to multiple receivers.Compared with the traditional one-to-one communication,it could improve the computational efficiency of communication and has been widely used in practical applications.Recently the identity-based multi-recipient encryption scheme had received more and more attention from researchers,since it did not require the certificate management center and reduced the system's storage expenses.However,there is the key escrow problem in such a cryptographic system.For this problem,the researchers proposed certificateless multi-recipient encryption.In the certificateless multi-receiver encryption cryptography,the private keys of all users were usually composed of two parts,one of which was generated by themselves and the other was generated by KGC(Key Generation Center),so KGC could not get the complete private keys of users.Therefore,the certificateless multi-receiver encryption cryptography solved the key escrow problem occured in identity-based multi-receiver encryption cryptography and improved the security performance.However,we observed that most of the existing certificateless multi-receiver encryption schemes were low in computational efficiency because of using too many bilinear pairings,and were not suitable for large-scale distributed network applications.Although in 2015,Islam et al.proposed a certificateless multi-receiver encryption schemes without bilinear pairings,their scheme was still not high in computational efficiency because of using too many elliptic curve point multiplications in the encryption and decryption phase.Subsequently,although there was also some certificateless multi-receiver schemes based on ECC,these schemes still were still low in computational efficiency in encryption phase.Motivated by the above,this paper proposes a pairing-free multi-receiver signcryption scheme without the key escrow problem.The scheme achieves confidentiality and strong non-repudiation of the message.Meantime,in the new scheme,the user's private key is set as a secret value randomly selected by themselves,and KGC could only obtain the validated parameter of the public key and the identity information of the user.So KGC could not calculate the user's private key,and solve the key escrow problem in the existing schemes.In the signcryption phase,the sender uses the information between each receivers and himself to carry out signcryption,so that the elliptic curve point multiplications are much less than the same type of schemes,so the scheme improves the efficiency of the signcryption and solves the problem of low efficiency.In this scheme,the new polynomial technique is used instead of the Lagrange interpolation function,and the identity information of all the receivers is merged together as part of the ciphertext so that the recipient's identity information list is not directly transmitted in the ciphertext,so our scheme achieves receiver's anonymity in the random oracle model.In addition,compared with the existing schemes,our scheme is higher in computational efficiency and has better security performance and could be better suitable for distributed network applications,such as online meeting,DVD broadcast system,pay TV and so on.