Efficient Provably-Secure Hierarchical Key Assignment Schemes

Abstract

A hierarchical key assignment scheme is a method to assign some private information and encryption keys to a set of classes in a partially ordered hierarchy, in such a way that the private information of a higher class can be used to derive the keys of all classes lower down in the hierarchy.In this paper we design and analyze hierarchical key assignment schemes which are provablysecure and support dynamic updates to the hierarchy with local changes to the public information and without requiring any private information to be re-distributed.• We first consider the problem of constructing a hierarchical key assignment scheme by using as a building block a symmetric encryption scheme. We propose a new construction which is provably secure with respect to key indistinguishability, requires a single computational assumption, and improves on previous proposals.• Then, we show how to reduce key derivation time at the expense of an increment of the amount of public information, by improving a previous result.• Finally, we show how to construct a hierarchical key assignment scheme by using as a building block a public-key broadcast encryption scheme. In particular, one of our constructions provides constant private information and public information linear in the number of classes in the hierarchy.

Policy Privacy in Cryptographic Access Control

“…The rich literature on the interplay between cryptography and access control ranges from schemes that employ encryption and/or key-distribution schemes to implement various forms of hierarchical access control [21], [3], [30], [4], [16] to the design and implementation of cryptographic file systems [27], [7], [11], [26] and on to the recent cryptographic primitives motivated by access control [37], [24], [28], [31], [12], [6]. However, while the syntax, functionality and security of the primitives (e.g.…”

Simple, Efficient and Strongly KI-Secure Hierarchical Key Assignment Schemes

“…De Santis et al [12] proposed a construction which is based on symmetric encryption schemes only, achieves KI security and is simpler than the KI-secure scheme proposed in [8]. The construction uses only a chosen plaintext secure symmetric encryption scheme and the required private key storage is small at one key per class.…”

“…Formally, the hierarchy is modelled as a partially ordered set (poset), each data item is labelled by a class u in the hierarchy, and is encrypted using the encryption key k u corresponding to that class. Now a user, given access to the private information S u , can derive the relevant encryption key k v for any descendant class v, and hence gain access to the data of class v. Since the original paper by Akl and Taylor, a large number of different schemes have been proposed, offering different trade-offs in terms of the amount of public and private storage required and the complexity of key derivation -see for example [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Many additional issues are addressed in these works: time-dependent constraints, dynamic addition and removal of classes, and revocation, for example.…”

CloudHKA: A Cryptographic Approach for Hierarchical Access Control in Cloud Computing

“…They proposed an HKA scheme to enforce an HAC policy. After that, many researches proposed methods for improving performance, supporting dynamic access control policies, or providing distinct features [2,3,12,16,19,20,24,26,30]. Atallah et al formalized the security requirement for HKA schemes and provided an efficient and provably-secure HKA scheme against key recovery attacks [3].…”