A method and a system for managing network identity are provided. The method and the system realize a management mechanism of temporary identification (ID) and real ID, which simultaneously achieves functionalities such as anonymity, accounting, and authorization. A short-term certificate and a corresponding public/private key pair are used to protect a temporary ID usable for accounting. This protection prevents the temporary ID from theft. The user generates a digital signature in the reply to a charge schedule statement from the visited network. This procedure is incorporated into an existing authentication framework based on Transport Layer Security (TLS) in order to provide an undeniable payment mechanism. The payment mechanism is applicable in an environment of multiple network operators and reduces the difficulty of integrating network operators. The method and the system do not have to consult a certificate revocation list (CRL) for authentication and thus are able to shorten authentication time.