A method for authentication in a wireless network, the wireless network comprising a user equipment, UE, and an access node, wherein the UE is dual-mode and is equipped with a cellular interface and a WiFi interface, and a WiFi access point, AP, and a cellular base station are integrated into the access node, the method comprising the steps: sending, by the UE, an authentication request message to the access node, wherein the authentication request message comprises a UE identification and a cell identification to which the UE currently attaches via the cellular interface, determining, by the access node, if the UE sending the authentication request message is attached to a cell by checking the cell identification, and determining, by the access node, if the UE is one of UEs attached to the cell, according to the UE identification, wherein in case the access node confirms that the cell identification in the received authentication request message is the same as that of the cell it serves, and the UE identification in the authentication request message indicates a UE in the attached state, the method comprising the steps of: sending back, by the access node, an authentication response which includes a challenge text, once the UE receiving the authentication response over the WiFi interface, copying, by the UE, the challenge text into a new authentication message and encrypting the challenge text with a maintained key of the wireless network, wherein in a wireless network layer, both the UE and the cellular base station hold a common encrypted cipher key, which is uniquely used to encrypt a user data or signaling between the UE and the cellular base station, getting, by the access node, the new authentication message, decrypting, by the access node, the challenge text with the cipher key, comparing, by the access node, a decrypted result of the method step decrypting the challenge text with the cipher key and the challenge text originally sent out, and if the decrypted result is the same with the challenge text originally sent out, determining, by the access node, an authentication success and sending, by the access node, another authentication response to the UE to indicate the authentication success, else replying, by the access node, with an indication of an authentication fail. sending, by the UE, an authentication request message to the access node, wherein the authentication request message comprises a UE identification and a cell identification to which the UE currently attaches via the cellular interface, determining, by the access node, if the UE sending the authentication request message is attached to a cell by checking the cell identification, and determining, by the access node, if the UE is one of UEs attached to the cell, according to the UE identification, wherein in case the access node confirms that the cell identification in the received authentication request message is the same as that of the cell it serves, and the UE identification in the authentication request message indicates a UE in the attached state, the method comprising the steps of: sending back, by the access node, an authentication response which includes a challenge text, once the UE receiving the authentication response over the WiFi interface, copying, by the UE, the challenge text into a new authentication message and encrypting the challenge text with a maintained key of the wireless network, wherein in a wireless network layer, both the UE and the cellular base station hold a common encrypted cipher key, which is uniquely used to encrypt a user data or signaling between the UE and the cellular base station, getting, by the access node, the new authentication message, decrypting, by the access node, the challenge text with the cipher key, comparing, by the access node, a decrypted result of the method step decrypting the challenge text with the cipher key and the challenge text originally sent out, and if the decrypted result is the same with the challenge text originally sent out, determining, by the access node, an authentication success and sending, by the access node, another authentication response to the UE to indicate the authentication success, else replying, by the access node, with an indication of an authentication fail. sending back, by the access node, an authentication response which includes a challenge text, once the UE receiving the authentication response over the WiFi interface, copying, by the UE, the challenge text into a new authentication message and encrypting the challenge text with a maintained key of the wireless network, wherein in a wireless network layer, both the UE and the cellular base station hold a common encrypted cipher key, which is uniquely used to encrypt a user data or signaling between the UE and the cellular base station, getting, by the access node, the new authentication message, decrypting, by the access node, the challenge text with the cipher key, comparing, by the access node, a decrypted result of the method step decrypting the challenge text with the cipher key and the challenge text originally sent out, and if the decrypted result is the same with the challenge text originally sent out, determining, by the access node, an authentication success and sending, by the access node, another authentication response to the UE to indicate the authentication success, else replying, by the access node, with an indication of an authentication fail.