Compact Anonymous Hierarchical Identity-Based Encryption with Constant Size Private Keys

We present a new construction of anonymous hierarchical identity-based encryption (HIBE) over prime order groups. The distinct feature of our proposed scheme is that both private key and ciphertext have a constant size, which has never been achieved in all other existing anonymous HIBE schemes. Moreover, we utilized a double exponent technique to generate the ciphertext in order to provide anonymity. This simple and efficient method allows us to construct a more compact anonymous HIBE in prime order groups. Under the decisional bilinear n + 1-Diffie–Hellman exponent assumption and linear assumption, we show that the proposed scheme is secure and anonymous against chosen plaintext attacks in the standard model.