Abstract: A method for generating a one-time password (OTP) by using software only is provided. The method is suitable for generating a common dynamic password in a first electronic device and a second electronic device. First, an initial number is provided to the first electronic device and the second electronic devices. Then, a value is generated, encrypted into a transmission value according to the initial number, and transmitted to the second electronic device by the first electronic device. Next, the transmission value is decrypted by the second electronic device according to the initial number to obtain the value. Finally, a dynamic password is respectively generated in the first electronic device and the second electronic device according to the initial number and the value. Thereby, an OTP system is constituted.

Abstract: A method for verifying a server end apparatus, suitable for verifying the identity of a server end apparatus from a client end apparatus, is provided. In the present invention, authentication data is sent to the server end apparatus by the client end apparatus, such that the server end apparatus verifies the authentication data. Afterwards, the server end apparatus must return an initial number, which is preset by the user, to the client end apparatus to verify whether the initial number is correct or not. If the initial number is incorrect, the connection with the server end apparatus is shut down. Therefore, the efficiency for verifying the server end identity is strengthened, so as to enhance the security.