Identity-based Signcryption Under Standard Model And Certificateless Multi-signcryption Scheme

For the classic certificate-based public key cryptography algorithm,due to the one-to-one correspondence between the user's public key and the user,the user needs to store a large number of certificates,which leads to more complicated certificate management problems.Therefore,the exploration of new identity-based encryption algorithms and certificate-free encryption algorithms has become a hot topic for scholars at home and abroad.In the classic encryption method,the usual method is to first sign and encrypt a message,and sign the secret to combine the signature and the encryption into one.With the increasing scale of network information,the message requires multiple users to sign and the encryption system sent to multiple recipients has received more attention.The work of this paper has the following two points:(1)Aiming at the problem that the scheme in the current identity-based signcryption system is not efficient,a new identity-based multi-signcryption scheme is proposed based on the original scheme.The new scheme combines identity-based encryption with multi-sender signatures by using bilinear pairs on elliptic curves,resulting in a new secure and efficient multi-signcryption scheme.It is proved in the standard model that the identity-based multi-signcryption scheme is confidential and unforgeable.,and compares and analyzes with other schemes.The calculation results show that when the number of people participating in the signcryption is n(n>1),the power operation of the new scheme is reduced by(n-1)times,which greatly improves the signcryption efficiency of the multisigncryption.(2)In view of the multi-recipient problem of messages in the current network environment,some scholars have proposed the signcryption algorithm for multi-receivers.For the problem that the existing multi-recipient signcryption algorithm is not efficient,In the certificate-free environment,a new multi-message multi-recipient signcryption scheme is constructed by Lagrangian interpolation and non-bilinear pairing.Firstly,the correctness of the scheme is analyzed,and then the scheme is proved to meet the inseparable security attributes of the adaptive selection ciphertext attack.Compared with the existing signcryption scheme,the new scheme has higher computational efficiency,and the signcryption process only requires 2n+1 multiplication operations and n exponential operations.