Efficient Attribute-based Proxy Re-Encryption with Constant Size Ciphertexts

Attribute-based proxy re-encryption (ABPRE) allows a semi-trusted proxy to transform an encryption under an access-policy into an encryption under a new access policy, without revealing any information about the underlying message. Such a primitive facilitates fine-grained secure sharing of encrypted data in the cloud. In its key-policy flavor, the re-encryption key is associated with an access structure that specifies which type of ciphertexts can be re-encrypted. Only two attempts have been made towards realising key-policy ABPRE (KP-ABPRE), one satisfying replayable chosen ciphertext security (RCCA security) and the other claiming to be chosen ciphertext secure (CCA secure). We show that both the systems are vulnerable to RCCA and CCA attacks respectively. We further propose a selective CCA secure KP-ABPRE scheme in this work. Since we demonstrate attacks on the only two existing RCCA secure and CCA secure schemes in the literature, our scheme becomes the first KP-ABPRE scheme satisfying selective CCA security. Moreover, our scheme has an additional attractive property, namely collusion resistance. A proxy re-encryption scheme typically consists of three parties: a delegator who delegates his decryption rights, a proxy who performs re-encryption, and a delegatee to whom the decryption power is delegated to. When a delegator wishes to share his data with a delegatee satisfying an access-policy, the proxy can collude with the malicious delegatee to attempt to obtain the private keys of the delegator during delegation period. If the private keys are exposed, security of the delegator\u27s data is completely compromised. The proxy or the delegatee can obtain all confidential data of the delegator at will at any time, even after the delegation period is over. Hence, achieving collusion resistance is indispensable to real-world applications. In this paper, we show that our construction satisfies collusion resistance. Our scheme is proven collusion resistant and selective CCA secure in the random oracle model, based on Bilinear Diffie-Hellman exponent assumption

PHOABE : securely outsourcing multi-authority attribute based encryption with policy hidden for cloud assisted IoT

Attribute based encryption (ABE) is an encrypted access control mechanism that ensures efficient data sharing among dynamic group of users. Nevertheless, this encryption technique presents two main drawbacks, namely high decryption cost and publicly shared access policies, thus leading to possible users’ privacy leakage. In this paper, we introduce PHOABE, a Policy-Hidden Outsourced ABE scheme. Our construction presents several advantages. First, it is a multi-attribute authority ABE scheme. Second, the expensive computations for the ABE decryption process is partially delegated to a Semi Trusted Cloud Server. Third, users’ privacy is protected thanks to a hidden access policy. Fourth, PHOABE is proven to be selectively secure, verifiable and policy privacy preserving under the random oracle model. Five, estimation of the processing overhead proves its feasibility in IoT constrained environments

Attribute-based encryption with verifiable outsourced decryption

Ministry of Education, Singapore under its Academic Research Funding Tier 1; Singapore Management University; Agency for Science, Technology and Research (A*STAR) SERC Gran

Outsourced CP-ABE with Whitebox Accountability in IoT Systems

Cryptography based on identity and attributes enhances the chance of secure communication on a large scale. Several attribute-based encryption schemes achieve different objectives when used in various protocols. Most of these are suitable for large systems like cloud services. There are a few protocols which focus on reducing the computational overhead for lower end devices like Internet of Things sensors and actuators. It is desirable to have a mix of features in protocols for IoT security architecture. We first propose a scheme to ensure accountability in CPABE scheme FAME. The protocol is proven CPA-secure with full security in random oracle model. We also prove its accountability. We also propose a hybrid protocol that enforces user accountability and outsourced decryption in IoT systems and achieve full security in replayable chosen ciphertext attack (RCCA) under random oracle model

A Survey: Attribute Based Encryption for Secure Cloud

Cloud computing is an enormous area which shares huge amount of data over cloud services and it has been increasing with its on-demand technology. Since, with these versatile cloud services, when the delicate data stored within the cloud storage servers, there are some difficulties which has to be managed like its Security Issues, Data Privacy, Data Confidentiality, Data Sharing and its integrity over the cloud servers dynamically. Also, the authenticity and data access control should be maintained in this wide environment. Thus, Attribute based Encryption (ABE) is a significant version of cryptographic technique in the cloud computing environment. Public Key Encryption acts as the basic technique for ABE where it provides one to many encryptions, here, the private key of users & the cipher-text both rely on attributes such that, when the set of the attributes of users key matches set of attributes of cipher-text with its corresponding access policy, only then decryption is possible. Thus, an opponent could grant access to the sensitive information that holds multiple keys, if it has at least one individual key for accession. The techniques based on ABE consist of two types: KP-ABE (Key- Policy ABE) where the user’s private key is linked to an access structure (or access policy) over attributes and cipher-text is connected to the set of attributes, and CP-ABE (cipher-text policy ABE) is vice versa. Hence, in this, Review we discuss about the various security techniques and relations based on Attributes Based Encryption, especially, the type KP-ABE over data attributes which explains secured methods & its schemes related to time specifications.&nbsp

A review of the state of the art in privacy and security in the eHealth cloud

The proliferation and usefulness of cloud computing in eHealth demands high levels of security and privacy for health records. However, eHealth clouds pose serious security and privacy concerns for sensitive health data. Therefore, practical and effective methods for security and privacy management are essential to preserve the privacy and security of the data. To review the current research directions in security and privacy in eHealth clouds, this study has analysed and summarized the state of the art technologies and approaches reported in security and privacy in the eHealth cloud. An extensive review covering 132 studies from several peer-reviewed databases such as IEEE Xplore was conducted. The relevant studies were reviewed and summarized in terms of their benefits and risks. This study also compares several research works in the domain of data security requirements. This paper will provide eHealth stakeholders and researchers with extensive knowledge and information on current research trends in the areas of privacy and security

Data Service Outsourcing and Privacy Protection in Mobile Internet

Mobile Internet data have the characteristics of large scale, variety of patterns, and complex association. On the one hand, it needs efficient data processing model to provide support for data services, and on the other hand, it needs certain computing resources to provide data security services. Due to the limited resources of mobile terminals, it is impossible to complete large-scale data computation and storage. However, outsourcing to third parties may cause some risks in user privacy protection. This monography focuses on key technologies of data service outsourcing and privacy protection, including the existing methods of data analysis and processing, the fine-grained data access control through effective user privacy protection mechanism, and the data sharing in the mobile Internet