Theory of Cryptography

Volume 5978 of the series Lecture Notes in Computer Science pp 455-479

New Techniques for Dual System Encryption and Fully Secure HIBE with Short Ciphertexts

  • Allison LewkoAffiliated withUniversity of Texas
  • , Brent WatersAffiliated withUniversity of Texas


We construct a fully secure HIBE scheme with short ciphertexts. The previous construction of Boneh, Boyen, and Goh was only proven to be secure in the selective model, under a non-static assumption which depended on the depth of the hierarchy. To obtain full security, we apply the dual system encryption concept recently introduced by Waters. A straightforward application of this technique is insufficient to achieve short ciphertexts, since the original instantiation of the technique includes tags that do not compress. To overcome this challenge, we design a new method for realizing dual system encryption. We provide a system in composite order groups (of three primes) and prove the security of our scheme under three static assumptions.