[BBG05] Hierarchical Identity Based Encryption with Constant Size Ciphertext

Authors: Dan Boneh, Xavier Boyen, Eu-Jin Goh | Venue: Eurocrypt 2005 | Source

Abstract

We present a hierarchical identity based encryption (HIBE) system where the ciphertext consists of just three group elements and decryption requires only two bilinear map computations, regardless of the hierarchy depth. The scheme is fully secure under the Bilinear Diffie-Hellman Exponent (BDHE) assumption without random oracles. Previous HIBE systems had ciphertext size and decryption time that grow linearly with the depth of the hierarchy. The key size in our scheme grows linearly with the hierarchy depth, but this is acceptable in many applications where private key storage is cheap but ciphertext communication is expensive. We also describe related identity based signature and ring signature schemes with constant ciphertext/signature size.