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.