Distributed Private-Key Generation Scheme with Self-Certified Identity

In an identity-based encryption (IBE) system, a private-key generator (PKG) is assumed to be credible, which takes charge of identity authentication and private-key issuing for users. However, the reliability of IBE may be questioned since this assumption does not always hold. In this paper, we propose a new distributed private-key generation scheme with self-certified identity (SCI-DKG) which does not need any PKG. SCI-DKG takes advantage of distributed private key generation and self certification to remove PKG from IBE. Comparing with the existing IBE schemes, a user and his identity can be independently authenticated through his blind digital ID (BDID) card and identity signature. In the meanwhile, a user can extract private keys from other users' sharing packets containing secret shares, partial public parameters and BDID cards. The proposed scheme significantly extends IBE without involvement of PKGs, and provides a promising solution for applications where PKG is not always available. Theoretical analysis demonstrates that our scheme is secure and effective.