Abstract: The present invention discloses a method and device of generating asymmetrical key pair (public key and private key) based on user identity. Key Management Center (KMC) generates public/private key calculating base, and publish the public key calculating base. Based on identity provided by a user, a private key is calculated and provided to the user. Any user can calculate other user's public key based on other user's identity and the published public key calculating base. Thus, when obtaining the public key of the communicating party, no third party CA certificate is needed, and no maintenance of mass parameters associated with users are needed.