Identity-Based Cryptography in Public Key Management

To guarantee the authenticity of public keys, traditional PKC (Public Key Cryptography) requires certificates signed by a CA (Certification Authority). However, the management of infrastructure supporting certificates is the main complaint against traditional PKC. While identity-based PKC can eliminate this cumbersome infrastructure, the key escrow of a user’s private key is inherent in identity-based PKC. Recently, new PKC paradigms were introduced: certificate-less PKC and certificate-based PKC. They retain the desirable properties of identity-based PKC without the inherent key escrow problem. A certificate-less cryptosystem eliminates the need for unwieldy certificates and a certificate-based cryptosystem simplifies the public key revocation problem. In this paper, we present an equivalence theorem among identity-based encryption, certificate-less encryption, and certificate-based encryption. We demonstrate that the three paradigms are essentially equivalent.