A system and method of multi-factor authentication are described. In some embodiments, a first device provides an initial authentication data to a second device. The second device is different from the first device. The first device obtains a first response data from the second device. The first device generates a first subsequent authentication data using the first response data. The first subsequent authentication data is different from the initial authentication data. The first device provides the first subsequent authentication data to the second device. In some embodiments, obtaining the first response data comprises capturing the first response data from the second device using a camera on the mobile device, where the first response data is displayed on the second device.