Fully Secure Functional Encryption: Attribute-Based Encryption and (Hierarchical) Inner Product Encryption

In this paper, we present two fully secure functional encryption schemes. Our first result is a fully secure attribute-based encryption (ABE) scheme. Previous constructions of ABE were only proven to be selectively secure. We achieve full security by adapting the dual system encryption methodology recently introduced by Waters and previously leveraged to obtain fully secure IBE and HIBE systems. The primary challenge in applying dual system encryption to ABE is the richer structure of keys and ciphertexts. In an IBE or HIBE system, keys and ciphertexts are both associated with the same type of simple object: identities. In an ABE system, keys and ciphertexts are associated with more complex objects: attributes and access formulas. We use a novel information-theoretic argument to adapt the dual system encryption methodology to the more complicated structure of ABE systems. We construct our system in composite order bilinear groups, where the order is a product of three primes. We prov...

• Type: Conference
• Year: 2010
• Where: EUROCRYPT
• Authors: Allison B. Lewko, Tatsuaki Okamoto, Amit Sahai, Katsuyuki Takashima, Brent Waters
• Keywords: Cryptology, Encryption, Encryption Methodology, EUROCRYPT 2010, Secure Attribute-based Encryption