A New Hierarchical ID-Based Cryptosystem and CCA-Secure PKE

A new hierarchical identity based (ID-based) cryptosystem is proposed, including hierarchical identity based encryption (HIBE) and signature (HIBS) schemes. The new HIBE scheme can be proved to be secure without relying on the random oracle model. Then, a new public key encryption (PKE) scheme is constructed based on the new HIBE. It is secure against adaptively chosen ciphertext attacks (IND-CCA) and has many attractive properties, such as efficient key generation, short private key, fast encryption, and etc. Performance of the new PKE scheme is better than all the previous PKE schemes converted from IBE, and is competitive with the best provably secure solutions to date. Furthermore, a new HIBS scheme is also constructed, which shares the same parameters with the new HIBE. The new HIBS scheme is more efficient than the previous HIBS.