The authors, Al-Riyami and Paterson, aimed to address the issue of key custody in the identity-based model, specifically targeting the encryption protocol developed by Boneh and Franklin (2003).
Their proposed approach, Certificate-Based Public Key Cryptography (CL-PKC), seeks to enhance two existing models.
Compared to traditional Public Key Cryptography (PKC), CL-PKC simplifies the structure by eliminating the need for digital certificates.
In contrast to the identity-based model (ID-PKC), it improves security by removing the requirement for key escrow.
One advantage of the system, is that it is possible to verify that any such obtained public key belongs to the stated identity string.