Certificates and the public key infrastructure (PKI) play an vital role in electronic commerce. The framework of splitting the public key in the PKI is presented in this paper. Aimed to enhance the security level from both the perspectives of certificate issuing and certificate revocation, the framework splits the public key into multiple parts, and generates a certificate for each part. The framework is designed to be flexible to allow various levels of security depending on the requirements, while minimising changes to the existing e-commerce system and PKI. The key-split system maintains CA independence and allows for either smaller certificates or the size of key to be increased.