How to Solve Key Escrow and Identity Revocation in Identity-Based Encryption Schemes

摘要

In identity-based cryptography, a user's public key is easily derived from the user's identity and a corresponding private key is generated for the user by a trusted third party, known as a Key Generation Center (KGC). The direct derivation of public keys in identity-based cryptography can eliminate the need for certificates and can solve certain public key management problems. Identity-based cryptography has many advantages for public key management, but it has two drawbacks that prevent its practical application in the real world: key escrow problems and lack of support for a fine-grained revocation of identity. At present, there is no solution that can simultaneously solve both problems; schemes that can solve the key escrow problem still have the identity revocation problem, and vice versa. In this paper, we consider a secure identity-based encryption scheme to support a fine-grained revocation without key escrow and also present a mediated key agreement protocol based on the same setting. Using the proposed scheme, we can apply identity-based cryptography more securely and practically in the real world.