Paper 2018/963

On Enabling Attribute-Based Encryption to Be Traceable against Traitors

Zhen Liu and Duncan S. Wong

Abstract

Attribute-Based Encryption (ABE) is a versatile one-to-many encryption primitive which enables fine-grained access control over encrypted data. Due to its promising applications in practice, ABE has been attracting much attention in the community and schemes with better security, access policy expressivity, and efficiency have been continuously emerging. On the other hand, due to the nature of ABE, namely, different users may share some common decryption privileges and a malicious user may leak some common decryption privileges for financial gain or other incentives, being able to identify such malicious users (i.e. traitor tracing) is crucial towards the practicality of an ABE system. For some existing ABE schemes with appealing properties (e.g. full security, large universe), the corresponding traceable counterparts have been proposed. However, these works are proceeded case by case, and there are still many appealing ABE schemes not having the traceable counterparts. Furthermore, when any new ABE scheme emerges and we want to apply it in practice, it will take significant workload to investigate and propose its traceable counterpart. In this paper, we propose a framework to transform existing and (possibly) future ABE schemes to their traceable counterparts in a generic manner. In particular, by specifying some requirements on the structure of the ABE constructions, we propose an ABE template, and show that any ABE scheme satisfying this template can be transformed to a fully collusion-resistant blackbox traceable ABE scheme in a generic manner, at the cost of sublinear overhead, while keeping the appealing properties, such as fine-grained access control on encrypted data, highly expressive access policy, short ciphertext, and so on. We prove the security in the framework all in the standard model, and we present a couple of existing ABE schemes with appealing properties as examples that do satisfy our ABE template.