Research On Public Key Cryptosystem With Equality Test And Its Application

How to maintain the confidentiality of data while ensuring its availability in the open environment has always been the focus of cryptography and information security.The public key cryptography which supports the functionality of ciphertext equality test is one of the most effective methods to solve the above problems.This technology allows an untrusted third party to test the ciphertext without decryption,in which the ciphertext being tested can be both the ciphertext encrypted under the same public key and different public keys.In addition,the plaintext corresponding to the ciphertext can not be obtained by the third party in the process of performing the equality test.This primitive not only ensures the confidentiality of data,but also greatly improves the availability of data,and has a good application prospect in ciphertext retrieval and classification.However,there are still some challenges in the public key encryption scheme with the functionality of equality test.For example,the existing certificateless encryption schemes with equality test have obvious deficiencies in security or performance,which can not satisfy the needs of the actual scenario.Moreover,the state-of-art schemes support equality test functionality are aimed at a single cryptosystem,which is not suitable for complex heterogeneous networks such as the Internet of Things.In view of the above problems,this thesis researches the existing schemes that support the equality test functionality,and mainly completes the following work:1)In this thesis,a certificateless encryption scheme supporting equality test functionality in Internet of Vehicle(Io V)is proposed.Since the secret key is composed of two parts,the key escrow problem in the identity-based encryption scheme is well solved.On the other hand,the public key of this scheme is public information,thus avoids the complicated problem of certificate management.At the same time,both theoretical analysis and experimental evaluation indicate the security,efficiency,as well as effectiveness of the proposed scheme which is suitable for lightweight devices with limited resources.2)The existing signcryption schemes with equality test aim at a sole cryptosystem and not suitable for the sophisticated heterogeneous network of Industrial Internet of Things(IIoT).To deal with this challenge,this thesis proposes a heterogeneous signcryption scheme with equality test(HSC-ET).In this scheme,the sensors in the public key infrastructure can signcrypt the data and deliever it to the semi-trusted entity(cloud server).When users in the identity-based cryptosystem intends to retrieve some data stored on the cloud server,the delegated cloud server executes tests on ciphertexts for determining whether the same underlying plaintext exists between the two ciphertexts.Meanwhile,confidentiality,integrity as well as authenticity of uploaded data are preserved.HSC-ET is demonstrated to be secure by the rigorous and detailed analysis.At the same time,according to the actual situation,the scheme can switch between heterogeneous signcryption and standard identity-based encryption,thus ensuring the flexibility of the scheme.And the experimental simulation and analysis results show the efficiency of our scheme.