An efficient ID-based delegation network

Delegation of signing capability is a common practice in various applications. Mambo et al. proposed a proxy signatures as a solution for delegation of signing capability. Proxy signatures allow a designated proxy signer to sign on behalf of an original signer. After the concept of proxy signature scheme was proposed, many variants are proposed to support more general delegation setting. To capture all possible delegation structures, the concept of delegation network was introduced by Aura, and an ID-based delegation network was proposed by Chow et al. In the computational point of view, their solution requires E pairing operations and N elliptic curve scalar multiplications where E and N are the number of edges and nodes in a delegation structure, respectively. In this paper, we proposed an efficient ID-based delegation network which requires only E pairing operations. Moreover, we modify our delegation network, and the modified scheme requires only N pairing operations. In general, E is larger than N and E increases according to the complexity of the network. So the modified delegation network is remarkably efficient than the previous delegation network.