Why do we need PKI Public key technology How to provide digital signature How to achieve non- repudiation service How to establish a connection between the public key and the identity How can we be sure that this is someone s public key Public key permissions How to manage public keys Solution certificate Associate the public key with an identity through a certificate 復大辱软件学院 LiJTLiJT Why do we need PKI • Public key technology – How to provide digital signature – How to achieve non-repudiation service – How to establish a connection between the public key and the identity • How can we be sure that this is someone's public key • Public key permissions – How to manage public keys • Solution：certificate – Associate the public key with an identity through a certificate