Research On Ciphertext-Policy Weighted Attribute-Based Encryption

Attribute-based encryption is the technology that encrypts files based on the attributes of users.In attribute-based encryption systems,the user's iden-tity is represented by a collection of attributes often with different importance The weight has a wide range of applications in real life,which can be used to measure the importance of a factor in things.It has become a promising re-search direction of attribute-based encryption to combine weights and attributes to enrich the expression of access control policy.Most of the existing ciphertext-policy attribute-based encryption schemes rarely consider the practical meaning of weights.On the other hand,existing ciphertext-policy weighted attribute-based encryption schemes also cause the structure of access control policies to be cum-bersome and the operation efficiency is low due to weighting methods.How to improve the operation efficiency of the ciphertext-policy weighted attribute-based encryption is the problem we need to considerData sharing plays an important role in the cloud computing environment The proxy re-encryption is a secure transformation mechanism for ciphertexts,which can realize the sharing of ciphertexts in the cloud computing environment Existing ciphertext-based weighted attribute encryption schemes rarely conduct related research on proxy re-encryption of ciphertexts.At the same time,it be-comes very difficult for users to obtain relevant files in a large number of databases after the data accumulate to a certain extent,which affects the development and applications of weighted attribute-based encryption.How to implement the ci-phertext transformation and retrieval in the ciphertext-based weighted attribute encryption schemes is another problem we have studiedIn response to problems raised above,this paper proposes three schemes(1)The paper adds the concept of weights to existing attribute-based encryption systems and proposes a new ciphertext-policy weighted attribute-based encryp-tion scheme.The authority assigns different weights to attributes using numerical weighting method based on the importance of attributes in the system.This method avoids generating too many attributes.We use an linear secret sharing scheme to share ciphertexts and use an Shamir threshold secret sharing scheme to share the weight threshold,which improve the efficiency while achieve the weighted attribute-based encryption function.(2)In order to further improve the efficiency of encryption and decryption,we propose an improved ciphertext-policy weighted attribute-based encryption scheme based on the new scheme.This scheme pri-oritizes the combination of similar attributes,reduces the number of attributes,introduces a multi-attribute authority to share the pressure of the original author-ity to distribute keys and uses a proxy server to pre-decrypt ciphertexts.Under the assumption of the decisional parallel bilinear Diffie-Hellman exponent problem,both of the above schemes are resistant to adaptive choice-plaintext attacks in the random oracle model.(3)This paper proposes a weighted attribute-based proxy re-encryption scheme supporting keywords dynamic searching by adding a proxy re-encryption function and a dynamic searchable function.The scheme allows a semi-trusted proxy to transform a ciphertext under an access control police to the one with the same plaintext under another access control policy(i.e.,attribute-based re-encryption).Users can search for keywords stored on the cloud server and dynamically add and delete ciphertexts.The scheme is proved to be indistinguish-able against adaptively chosen-key attack in the random oracle model.Besides,under the assumption of the decisional parallel bilinear Diffie-Hellman exponent problem,the scheme is indistinguishable against adaptively chosen-plaintext at-tack in the random oracle model.Finally,the scheme is compared with other schemes.It is concluded that the scheme is superior to the same type of scheme in performance.The calculation amount is smaller,and the search efficiency is higher.This scheme is more suitable for the current cloud computing environment.