An Efficient Key Management Infrastructure for Personal Health Records in cloud

Personal Health Record (PHR) allows patients to create, manage, control and share their health information with other users as well as healthcare providers. The PHR is stored in “honest but curious” cloud servers and the system has serious privacy and security issues like cryptographic attacks, unknown access to the data etc. To overcome these issues, a novel and Efficient Key Management Infrastructure (EKMI) is proposed, which divides the system into two domains namely public domain (PUDs) and personal domain (PSDs) to achieve fine grained access control. The PUDs consists of users who make access based on their professional roles, such as doctors, nurses and medical researcher. The PSD users are personally associated with a data owner such as family members or close friends and they make access to PHR based on access rights assigned by the owner. In PHR unknown users may access the sensitive data; to overcome this revocation is proposed. Revocation is the process of revoking the users from their access. EKMI uses a new Decentralized Key Policy Attribute based Encryption (DKPABE) with user revocation in Private Domain and Multi Authority Cipher text Policy Attribute Based Encryption (MACPABE) with attribute revocation in Public Domain. In revocation Lazy revocation concept is used to reduce the computation overhead on cloud server. The EKMI system proves to be resistant to collusion attacks by employing Tokenization concept in above algorithms. The experimental analysis shows that the EKMI system reduces the time complexity of key generation for both domains and hence it is efficient when compared to existing systems.