关键词: 椭圆曲线密码体制, 多接收者, 签密, 随机Oracle模型, 无证书

Abstract: To address the issues of user privacy protection and adaptive message quantity in multireceiver broadcast signcryption, a certificateless multireceiver multimessage adaptive broadcast signcryption mechanism was proposed. The receiver identity ID is input into the Lagrange interpolation polynomial to calculate the ciphertext index, and the receiver uniquely locates the signcryption ciphertext, which solves the problem of selfadaptation of the number of messages in the broadcast signcryption. Based on the elliptic curve cryptography, the user decryption key is associated with a random element on the group to solve the privacy protection problem of multireceiver users. Under the random Oracle model, based on the discrete logarithmic assumption and the computational DiffieHellman assumption on the elliptic curve additive cyclic group, it is proved that the scheme satisfies confidentiality and unforgeability. The functional efficiency analysis shows that the scheme is superior to the traditional multireceiver signcryption scheme.

Key words: elliptic curve cryptosystem, multireceiver, signcryption, random Oracle model, certificateless