Attribute-based encryption for cloud computing access control: A survey

National Research Foundation (NRF) Singapore; AXA Research Fun

A Review on Cloud Data Security Challenges and existing Countermeasures in Cloud Computing

Cloud computing (CC) is among the most rapidly evolving computer technologies. That is the required accessibility of network assets, mainly information storage with processing authority without the requirement for particular and direct user administration. CC is a collection of public and private data centers that provide a single platform for clients throughout the Internet. The growing volume of personal and sensitive information acquired through supervisory authorities demands the usage of the cloud not just for information storage and for data processing at cloud assets. Nevertheless, due to safety issues raised by recent data leaks, it is recommended that unprotected sensitive data not be sent to public clouds. This document provides a detailed appraisal of the research regarding data protection and privacy problems, data encrypting, and data obfuscation, including remedies for cloud data storage. The most up-to-date technologies and approaches for cloud data security are examined. This research also examines several current strategies for addressing cloud security concerns. The performance of each approach is then compared based on its characteristics, benefits, and shortcomings. Finally, go at a few active cloud storage data security study fields

TKSE: Trustworthy keyword search over encrypted data with two-side verifiability via blockchain

AXA Research Fund Singapor

Data exploitation and privacy protection in the era of data sharing

As the amount, complexity, and value of data available in both private and public sectors has risen sharply, the competing goals of data privacy and data utility have challenged both organizations and individuals. This dissertation addresses both goals. First, we consider the task of {\it interorganizational data sharing}, in which data owners, data clients, and data subjects have different and sometimes competing privacy concerns. A key challenge in this type of scenario is that each organization uses its own set of proprietary, intraorganizational attributes to describe the shared data; such attributes cannot be shared with other organizations. Moreover, data-access policies are determined by multiple parties and may be specified using attributes that are not directly comparable with the ones used by the owner to specify the data. We propose a system architecture and a suite of protocols that facilitate dynamic and efficient interorganizational data sharing, while allowing each party to use its own set of proprietary attributes to describe the shared data and preserving confidentiality of both data records and attributes. We introduce the novel technique of \textit{attribute-based encryption with oblivious attribute translation (OTABE)}, which plays a crucial role in our solution and may prove useful in other applications. This extension of attribute-based encryption uses semi-trusted proxies to enable dynamic and oblivious translation between proprietary attributes that belong to different organizations. We prove that our OTABE-based framework is secure in the standard model and provide two real-world use cases. Next, we turn our attention to utility that can be derived from the vast and growing amount of data about individuals that is available on social media. As social networks (SNs) continue to grow in popularity, it is essential to understand what can be learned about personal attributes of SN users by mining SN data. The first SN-mining problem we consider is how best to predict the voting behavior of SN users. Prior work only considered users who generate politically oriented content or voluntarily disclose their political preferences online. We avoid this bias by using a novel type of Bayesian-network (BN) model that combines demographic, behavioral, and social features. We test our method in a predictive analysis of the 2016 U.S. Presidential election. Our work is the first to take a semi-supervised approach in this setting. Using the Expectation-Maximization (EM) algorithm, we combine labeled survey data with unlabeled Facebook data, thus obtaining larger datasets and addressing self-selection bias. The second SN-mining challenge we address is the extent to which Dynamic Bayesian Networks (DBNs) can infer dynamic behavioral intentions such as the intention to get a vaccine or to apply for a loan. Knowledge of such intentions has great potential to improve the design of recommendation systems, ad-targeting mechanisms, public-health campaigns, and other social and commercial endeavors. We focus on the question of how to infer an SN user\u27s \textit{offline} decisions and intentions using only the {\it public} portions of her \textit{online} SN accounts. Our contribution is twofold. First, we use BNs and several behavioral-psychology techniques to model decision making as a complex process that both influences and is influenced by static factors (such as personality traits and demographic categories) and dynamic factors (such as triggering events, interests, and emotions). Second, we explore the extent to which temporal models may assist in the inference task by representing SN users as sets of DBNs that are built using our modeling techniques. The use of DBNs, together with data gathered in multiple waves, has the potential to improve both inference accuracy and prediction accuracy in future time slots. It may also shed light on the extent to which different factors influence the decision-making process

Accountable Authority Ciphertext-Policy Attribute-Based Encryption with White-Box Traceability and Public Auditing in the Cloud

As a sophisticated mechanism for secure fine-grained access control, ciphertext-policy attribute-based encryption (CP-ABE) is a highly promising solution for commercial applications such as cloud computing. However, there still exists one major issue awaiting to be solved, that is, the prevention of key abuse. Most of the existing CP-ABE systems missed this critical functionality, hindering the wide utilization and commercial application of CP-ABE systems to date. In this paper, we address two practical problems about the key abuse of CP-ABE: (1) The key escrow problem of the semi-trusted authority; and, (2) The malicious key delegation problem of the users. For the semi-trusted authority, its misbehavior (i.e., illegal key (re-)distribution) should be caught and prosecuted. And for a user, his/her malicious behavior (i.e., illegal key sharing) need be traced. We affirmatively solve these two key abuse problems by proposing the first accountable authority CP-ABE with white-box traceability that supports policies expressed in any monotone access structures. Moreover, we provide an auditor to judge publicly whether a suspected user is guilty or is framed by the authority

Leak-Free Mediated Group Signatures

Group signatures are a useful cryptographic construct for privacy-preserving non-repudiable authentication, and there have been many group signature schemes. In this paper, we introduce a variant of group signatures that offers two new security properties called leak-freedom and immediate-revocation. Intuitively, the former ensures that an insider (i.e., an authorized but malicious signer) be unable to convince an outsider (e.g., signature receiver) that she indeed signed a certain message; whereas the latter ensures that the authorization for a user to issue group signatures can be immediately revoked whenever the need arises (temporarily or permanently). These properties are not offered in existing group signature schemes, nor captured by their security definitions. However, these properties might be crucial to a large class of enterprise-centric applications because they are desirable from the perspective of the enterprises who adopt group signatures or are the group signatures liability-holders (i.e., will be hold accountable for the consequences of group signatures). In addition to introducing these new securit

Dynamic Credentials and Ciphertext Delegation for Attribute-Based Encryption

Motivated by the question of access control in cloud storage, we consider the problem using Attribute-Based Encryption (ABE) in a setting where users\u27 credentials may change and ciphertexts may be stored by a third party. We find that a comprehensive solution to our problem must simultaneously allow for the revocation of ABE private keys as well as allow for the ability to update ciphertexts to reflect the most recent updates. Our main result is obtained by pairing two contributions: - Revocable Storage. We ask how a third party can process a ciphertext to disqualify revoked users from accessing data that was encrypted in the past, while the user still had access. In applications, such storage may be with an untrusted entity and as such, we require that the ciphertext management operations can be done without access to any sensitive data (which rules out decryption and re-encryption). We define the problem of revocable storage and provide a fully secure construction. Our core tool is a new procedure that we call ciphertext delegation. One can apply ciphertext delegation on a ciphertext encrypted under a certain access policy to `re-encrypt\u27 it to a more restrictive policy using only public information. We provide a full analysis of the types of delegation possible in a number of existing ABE schemes. - Protecting Newly Encrypted Data. We consider the problem of ensuring that newly encrypted data is not decryptable by a user\u27s key if that user\u27s access has been revoked. We give the first method for obtaining this revocation property in a fully secure ABE scheme. We provide a new and simpler approach to this problem that has minimal modifications to standard ABE. We identify and define a simple property called piecewise key generation which gives rise to efficient revocation. We build such solutions for Key-Policy and Ciphertext-Policy Attribute-Based Encryption by modifying an existing ABE scheme due to Lewko et al. to satisfy our piecewise property and prove security in the standard model. It is the combination of our two results that gives an approach for revocation. A storage server can update stored ciphertexts to disqualify revoked users from accessing data that was encrypted before the user\u27s access was revoked. This is the full version of the Crypto 2012 paper