An arrangement for authenticating a transaction between a user's mobile device and an entity such as a corporate server is disclosed. The user's universal integrated circuit card (UICC) is adapted to generate a time-dependent authentication code which is dependent on a time value and which is usable to authenticate the transaction only during a predetermined period. A time verification processor verifies a time value to ensure that the time-dependent authentication code was generated based on the correct time value. The time value is based on the UTC time obtained from UTC clock. The verified time is used to generate a “one-time” password (authentication code) by the authentication code calculator of the UICC. This is used to authenticate a transaction with the corporate network.