IOSR Journal of Mathematics (IOSR-JM) e-ISSN: 2278-5728, p-ISSN: 2319-765X. Volume 15, Issue 5 Ser. I (sep – Oct 2019), PP 21-33 www.iosrjournals.org DOI: 10.9790/5728-1505012133 www.iosrjournals.org 21 | Page A Verifiable Ciphertext Policy Attribute-Based Encryption(VCP- ABE) Scheme with Keywords Search and Revocation Muqadar Ali,Chungen Xu, Abid Hussain, Laila Tul Badar (Mathematics, Nanjing University of Science and Technology, China) Corresponding Authors: Chungen Xu, Abid Hussain, Laila Tul Badar Abstract:Ciphertext policy attribute-based encryption(CP-ABE) scheme widely used in cloud storage for realizing the flexible and scalable fine-grained data access control for secure data sharing with user’s under certain credential or attribute’s. However most of the (CP-ABE) scheme have the problems such as access policy complexity, low computational efficiency, efficient revocation cannot be performed. Where traditional attribute-based encryption fails to provide efficient keyword’s search due to week encryption scheme. In this paper we proposed verifiable ciphertext policy attribute based encryption(VCP-ABE) scheme with efficient attribute’s user’s revocation and secure keyword search on the encrypted keywords index using keywords search trapdoor where many of existing (CP-ABE) cannot support keyword search. The cloud server cannot learn any information about the keywordssearch trapdoor. Our proposed scheme achieves large universe set and multiple authority with flexible number of attribute’s users. The data owner encrypts keywords index and ciphertext to cloud server under hidden access structure and access policy. Where many of outsource computing task can be done by the cloud proxy server CPS like outsource encryption, decryption and revoked related attribute’s user’s ciphertext update verification that greatly reduce the computational task at user’s client side. We provide details of correctness analysis, performance analysis and security proof against chosen keywords attack in standard model for our scheme. Keywords:Attribute-based encryption, Access control, Verifiability, Keyword search, Revocation --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 27-08-2019 Date of Acceptance: 11-09-2019 --------------------------------------------------------------------------------------------------------------------------------------- I. Introduction Attribute based encryption(ABE) is promising alternative technique that achieving fine grained access control for the encrypted data to related security threats via cryptographic mean. Where using public key encryption can be viewed as to share data with targeted users or the devices that should providing confidently from unauthorized users. The data provider knows the exact eligible user to share his data where the people are identified by the attribute’s which is not realistic, in practical application for the data access control in which the data owner want to convey based on access policy for the privilege user’s attributes. To solve this problem, the first attribute based encryption scheme ABE [1] proposed by Sahai and water where the attribute authority(AA) issues the secret key or key generation authority based on ABE for their attributes and the data provider specifies an access policy to set of attributes users. Only the users will be able to access and decrypt if he/she satisfy the access policy with access structure with associated ciphertext. To get a secret key each user’s must prove the legality with set of attributes through set of trusted attribute authority. Goyal et al and Bethencourt [2,3] formalized two supplementary form of ABE ciphertext policy attribute based encryption(CP-ABE) and key policy attribute based encryption(KPABE). In (KP-ABE) [2] the ciphertext associated to attribute set and secret key attach to access policy for fine grained data access control for users to decrypted the ciphertext. The (CP-ABE) [3] the secret key attach to ciphertext and access policy connected to attribute set, where each users possess private key to corresponding attribute’s set the ciphertext embedded into access policy, the attribute’s users can be decrypt the ciphertext if his attributes satisfy the access policy. To overcome this problem of security and privacy the concept of multi authority AAs [4,5] was introduce with central authority and each authority distribute secret key correspond to the different set of attributes for the ciphertext decryption. Since in the presence of ABE solve the security issue but the users with di fferent attributes user’s access different level of encrypted data that fails the attribute user may be change with time that is imitated as attribute’s revocation. To solve this problem with attribute user’s revocation to periodically update key that allow only non-revoked user’s to update secret key for thedecryption of newly encrypted data. In the scenario of revocable ABE [6] consists of two method i) indirect revocation in which the data sender encrypts his data under attribute set the and for fixed time the attribute authority according to revoked attribute list update the secret key for non- revoked attribute user’s in each time periodically for the current ciphertext decryption. ii) Direct revocation in which sender during encryption algorithm specify the revocation list so that the data owner doesn’t need to