Biblio

Ciphertext policy Attribute-based encryption (CPABE) plays an increasingly important role in the field of fine-grained access control for cloud storage. However, The exiting solution can not balance the issue of user identity tracking and user revocation. In this paper, we propose a CP-ABE scheme that supports association revocation and traceability. This scheme uses identity directory technology to realize single user revocation and associated user revocation, and the ciphertext re-encryption technology guarantees the forward security of revocation without updating the private key. In addition, we can accurately trace the identity of the user according to the decryption private key and effectively solve the problem of key abuse. This scheme is proved to be safe and traceable under the standard model, and can effectively control the computational and storage costs while maintaining functional advantages. It is suitable for the practical scenarios of tracking audit and user revocation.

Ciphertext-policy Attributes-based Encryption (CP-ABE) is an encouraging cryptographic mechanism. It behaves an access control mechanism for data security. A ciphertext and secret key of user are dependent upon attributes. As a nature of CP-ABE, the data owner defines access policy before encrypting plaintext by his right. Therefore, CP-ABE is suitable in a real environment. In CP-ABE, the revocation issue is demanding since each attribute is shared by many users. A policy-based revolutionary CP-ABE scheme is proposed in this paper. In the proposed scheme, revocation takes place in policy level because a policy consists of threshold attributes and each policy is identified as a unique identity number. Policy revocation means that the data owner updates his policy identity number for ciphertext whenever any attribute is changed in his policy. To be a flexible updating policy control, four types of updating policy levels are identified for the data owner. Authorized user gets a secret key from a trusted authority (TA). TA updates the secret key according to the policy updating level done by the data owner. This paper tests personal health records (PHRs) and analyzes execution times among conventional CP-ABE, other enhanced CP-ABE and the proposed scheme.

Aiming at the increasing popularity of mobile terminals, a CP-ABE scheme adapted to lightweight decryption at the mobile end is proposed. The scheme has the function of supporting timely attributes revocation and policy hiding. Firstly, we will introduce the related knowledge of attribute base encryption. After that, we will give a specific CP-ABE solution. Finally, in the part of the algorithm analysis, we will give analysis performance and related security, and compare this algorithm with other algorithms.

Ciphertext policy attribute-based encryption (CP-ABE) is a promising technology that offers fine-grained access control over encrypted data. In a CP-ABE scheme, any user can decrypt the ciphertext using his secret key if his attributes satisfy the access policy embedded in the ciphertext. Since the same ciphertext can be decrypted by multiple users with their own keys, the malicious users may intentionally leak their decryption keys for financial profits. So how to trace the malicious users becomes an important issue in a CP-ABE scheme. In addition, from the practical point of view, users may leave the system due to resignation or dismissal. So user revocation is another hot issue that should be solved. In this paper, we propose a practical CP-ABE scheme. On the one hand, our scheme has the properties of traceability and large universe. On the other hand, our scheme can solve the dynamic issue of user revocation. The proposed scheme is proved selectively secure in the standard model.