A method includes sending, by a trusted application (TA) entity, a certificate of the TA entity and a private key signature of the TA entity to a target security domain (SD). The certificate and the private key signature enable the target SD to perform trust verification via a server, obtaining, by the TA entity, a first key of the target SD when the trust verification of the TA entity succeeds, and establishing, by the TA entity, a trust relationship with the target SD.