This invention relates to a negotiation and an update method for certified cryptographic keys based on public keys among interfaces of electronic equipments, in which, a source device and a destination device taking part in the negotiation select a single-way or double-way certification mode to finish the certification and negotiation and update of the cryptographic keys, in which, the one-way or double-way mode generates a shared secret by using the Diffie-Hellman cryptographic exchange technology to secure the consistency of the shared secret and the integrality of the protocol information by a HMAC cryptographic key hashing function and to secure the sender of the certificate to hold the private key corresponding to the public key in the certificate so as to determine the legality of the device, under the re-certification situation, the legality of the device is confirmed by using the shared cryptographic key.