Abstract: A system and method is for personal authentication with respect to a service provider using a mobile device. The method includes providing the user of the mobile device (2) with a two-dimensional code (1), the information contained in a two-dimensional code (1) including encrypted original data which includes an encrypted session key for certifying the user with respect to the service provider; the mobile device (2) obtaining an image containing the two-dimensional code (1) via an image capturing system; the mobile device (2) obtaining the two-dimensional code (1) from the image; the two-dimensional code (1) being converted into a character code. The mobile device (2) obtains the original data including the dynamic session key for authenticating the user before the service provider from the character code, by applying a decryption process.