CCA-secure ABE using tag and pair encoding

Jutla and Roy (Asiacrypt 2013) proposed the first tag-based identity-based encryption which Chen and Gong (Asiacrypt 2017) extended to construct CPA-secure attribute-based encryption (ABE) in prime-order groups. However, Chen and Gong used predicate encoding for ABE construction. In literature, there exists a more powerful encoding, namely, pair encoding which Attrapadung (Eurocrypt 2014, Asiacrypt 2016) introduced as a generic framework to construct CPA-secure attribute-based encryptions in prime order groups. In reality, however, CPA-secure encryptions are not always sufficient as a security requirement. Yamada et al. (PKC 2011, PKC 2012) suggested generic techniques to get CCA secure attribute-based encryptions from CPA-secure attribute-based encryptions. In this work, we achieve two-fold improvements. We provide a tag-based ABE construction that uses pair encoding and at the same time achieves CCA security from the matrix Diffie-Hellman assumption in the standard model. As a result, our tag-based ABE can be utilized to construct new attribute-based encryptions with multiple randomnesses required in both the secret key and the ciphertext. Moreover, the cost we pay for CCA security is still significantly less than the cost of generic approach of Yamada et al.