Mediated Hierarchical Identity-Based Combined Public Key Schemes

This paper presents the mediated hierarchical identity-based combined public key (mHIB-CPK) scheme by applying the concept of mediated hierarchical identity-based encryption (mHIBE) [1] to identity-based combined public key (IB-CPK) [2], which is an identity-based encryption (IBE) [3] scheme compatible with ElGamal [4] and other algorithms based on discrete logarithm problem (on prime fields or elliptic curves, such as [5], [6]). Besides the advantages from mHIBE (hierarchical key generation and efficient revocation) and IBCPK (compatible with popular public key algorithms), mHIBCPK prevents conspiracy attacks on IB-CPK [7], making it more practicable for large-scale users.