Biblio
Since a lot of information is outsourcing into cloud servers, data confidentiality becomes a higher risk to service providers. To assure data security, Ciphertext Policy Attributes-Based Encryption (CP-ABE) is observed for the cloud environment. Because ciphertexts and secret keys are relying on attributes, the revocation issue becomes a challenge for CP-ABE. This paper proposes an encryption access control (EAC) scheme to fulfill policy revocation which covers both attribute and user revocation. When one of the attributes in an access policy is changed by the data owner, the authorized users should be updated immediately because the revoked users who have gained previous access policy can observe the ciphertext. Especially for data owners, four types of updating policy levels are predefined. By classifying those levels, each secret token key is distinctly generated for each level. Consequently, a new secret key is produced by hashing the secret token key. This paper analyzes the execution times of key generation, encryption, and decryption times between non-revocation and policy revocation cases. Performance analysis for policy revocation is also presented in this paper.
In today's smart healthcare system, medical records of patients are exposed to a large number of users for various purposes, from monitoring the patients' health to data analysis. Preserving the privacy of a patient has become an important and challenging issue. outsourced Ciphertext-Policy Attribute-Based Encryption (CP-ABE) provides a solution for the data sharing and privacy preservation problem in the healthcare system in fog environment. However, the high computational cost in case of frequent attribute updates renders it infeasible for providing access control in healthcare systems. In this paper, we propose an efficient method to overcome the frequent attribute update problem of outsourced CP-ABE. In our proposed approach, we generate two keys for each user (a static key and a dynamic key) based on the constant and changing attributes of the users. Therefore, in case of an attribute change for a user, only the dynamic key is updated. Also, the key update is done at the fog nodes without compromising the security of the system. Thus, both the communication and the computational overhead associated with the key update in the outsourced CP-ABE scheme are reduced, making it an ideal solution for data access control in healthcare systems. The efficacy of our proposed approach is shown through theoretical analysis and experimentation.
The problem of optimizing the security policy for the composite information system is formulated. Subject-object model for information system is used. Combining different types of security policies is formalized. The target function for the optimization task is recorded. The optimization problem for combining two discretionary security policies is solved. The case of combining two mandatory security policies is studied. The main problems of optimization the composite security policy are formulated. +50 CHMBOJIOB‼!