| In recent decades,people have made great progress in research on lattices,discovered the various properties of lattices,and optimized calculation methods.This has greatly enriched and expanded the research category of lattices-base signcryption,and based on the assumption of lattices.The problem can be proved to be safe in the worst case,which makes the lattices-based cryptography the main force of the post-quantum cryptography.However,these advantages can not make people ignore the problem that the key space of the lattice key is large,inefficient,and makes It difficult to promote.Signcryption is a kind of cryptography primitive that is used simultaneously for signature and encryption.Its key ciphertext space and encryption time are much less expensive than first signing and encryption,which makes it have important applications in many scenarios.But after reseached the trapdoor function and the preimage sampling algorithm in the signcryption algorithm,we found that by using reasonable parameter settings and adding Gaussian sampling,the trapdoor function can be avoided in the key generation process of the signcryption scheme.Like the sampling algorithm,the signcryption scheme is transformed into a lattices-base signcryption scheme without trapdoors.This scheme has room for efficiency improvement to a certain extent,but the ordinary signcryption scheme relies on the third-party trusted organization to authenticate the certificate.The maintenance of this system resources is unfavorable.Therefore,this paper through the research of the lattices-base without trapdoor signcryption scheme,based on its identity-based features.The main work of this article is as follows:(1)Identity-based features are added to the lattices-base without trapdoor signcryption scheme to make the system save the resources to maintain the third-party trusted organization,and construct a identity-based on lattices without trapdoor signcryption scheme.Trapdoor signature and its signature compression technology,combined with the encryption method based on the learning problem with errors,generates a user private key by performing ID operation.The user can directly send the information by using the ID of the receiver and the private key of the sender.Signed secret,the recipient through its own private key solution signature.The new scheme avoids the use of third-party structures that can store user keys through certificates.The correctness of the scheme was proved,and the safety proof was constructed by using the statute proof to prove the safety of the scheme.The efficiency of the scheme was compared with similar schemes.(2)Based on the idea of identity-based on lattices without trapdoor signcryption schemes,this scheme can not satisfy mass-bursting and can only carry out one-to-one encrypted communication,and the identity is the user's unique identifier.Under certain circumstances,it is not conducive to user identity.In order to solve this kind of problem,this paper uses the idea of attribute signcryption to achieve the requirements of fuzzy identities and bursts.An attribute-based on lattices without trapdoor signcryption scheme is constructed.The new scheme is generated by compressing the attribute set through Merkle tree compression.The root node carries out the signcryption and proves the correctness of the scheme,and uses the statute proof to construct the security proof game to prove its safety,and compares the efficiency of the scheme with similar schemes.(3)In some special circumstances,the sender cannot participate in the signcryption process.In order to solve such scenarios,the author constructs a identity-base on lattices without trapdoor proxy signcryption scheme,and authorizes the certificate generation method to sign the certificate.The secret rights are transferred to the proxy,the agent signature is completed,the correctness of the scheme is proved,and the safety proof is constructed by using the statute proof to prove the safety and the efficiency of the scheme is compared with similar schemes. |
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