Abstract—The biggest problem in cloud is securing an outsourcing data. A cloud environment cannot be considered to be trusted. It becomes more challenging when outsourced data sources are managed by multiple outsourcers with different access rights. Several methods have been proposed to protect data confidentiality against the cloud service provider to support fine-grained data access control. We propose a method with combined Cipher Text Policy Attribute-based Encryption (CP-ABE) and Timed-release encryption (TRE) secure method to control medical data storage in public cloud. Keywords—Attribute, encryption, security, trapdoor. I. INTRODUCTION LOUD computing is an information technology that enables access to ubiquitous resources and services over an Internet. [1] A large number of services on infrastructure, platform and software have been developed by different providers. Remote services are ensured to use with a user's data, software and computation. With the strong security mechanism, remote data still face network attacks hardware failures and errors. To ensure correctness and securing a outsourced data becomes a challenging task in cloud computing II. WORKING OF CLOUD Cloud computing is a technology also termed as demand computing that provides processing of shared resources to computers and other devices on demand. These shared resources can be provisioned with least minimal effort such as networks, applications, storage and services. Cloud computing and storage solutions provide enterprises and users with several capabilities to store and process data in third party data centers. III. PROPOSED SYSTEM Hong et al. [1] used a combined scheme of CP-ABE and TRE. In our system same approaches are used with additional capabilities for securing our medical data. In the proposed system, patient data are secured with time factor with the help of the methods TRE and CP-ABE [10], practical methods are applied on medical data to get effective Shruthi G. is Research scholar, SIT, Tumakaru, India (phone: 9739049892, e-mail: shruthiindbit@gmail.com). Dr Purohith Shrinivasacharya is Associate Professor, Dept of ISE, SIT Tumkaru (e-mail: purohitsn@gmail.com). access with minimum difficulty to cipher policy text attribute encryption scheme. IV. ADVANTAGES OF PROPOSED SYSTEM 1) Medical data are secured from illegal access. 2) Risk of Trusted CA is reduced. 3) Risk of owners and users is reduced. 4) Patient data are secured by time seal. 5) Registered authenticated users are allowed to view the patient data within the time seal. 6) Users can search the patient file using the keywords. He can download the file by using the secret key. 7) Only the doctor can view and edit the file but the others and insurance company allowed only viewing the patient file without any modifications. 8) Secret key is generated only to the registered user and owners by AES algorithm V. LITERATURE SURVEY Li and Yu [11] have used combining techniques of attribute-based encryption (ABE), proxy re-encryption, and lazy re-encryption. Qin et al. [3] gave a solid and inspiring survey of proxy re- encryption from different perspectives to offer a better understanding of this primitive. They have reviewed the state- of-the-art of the proxy re-encryption by investigating the design philosophy, examining the security models and comparing the efficiency and security proofs of existing schemes. Ren et al. [5] explain different prominent challenges on security and motivate further findings of security solutions for a trusted public cloud environment Yang et al. [6] propose data access control for multi authority cloud storage (DAC-MACS), provide a secure data access control scheme with decryption and revocation. A new CP-ABE scheme called multi authority with decryption, and attribute suppression method was introduced with both forward security and backward security for weaker security assumptions. VII. SYSTEM DESIGN Data owner, search user, cloud service provider (ADMIN) and central authority are the four modules developed in the system design. Below is the description of each module provided. G. Shruthi, Purohith Shrinivasacharya A Combined Cipher Text Policy Attribute-Based Encryption and Timed-Release Encryption Method for Securing Medical Data in Cloud C World Academy of Science, Engineering and Technology International Journal of Computer and Information Engineering Vol:13, No:2, 2019 80 International Scholarly and Scientific Research & Innovation 13(2) 2019 ISNI:0000000091950263 Open Science Index, Computer and Information Engineering Vol:13, No:2, 2019 waset.org/Publication/10010068