This is how a TAN generator works - simply explained

There is no general explanation of how a TAN generator works. There are different types of TAN devices that generate a TAN in different ways. We will introduce you to all the generators.

Bank's TAN generators: how they work

• An generates the TAN via the chip on the customer card. This generator does not have a numeric key, but only a button that you can use to let the device create a TAN as soon as the card is inserted. Device and card are not bound to each other. You can generate TANs for any card with any . However, only the last TAN generated is valid.
• An eTAN generator has input keys. The TAN generator is individually connected to the customer card. So it doesn't work with all cards. The customer also receives a secret key. Combined with the time and the recipient's account number, the generator then creates a TAN, whereby the recipient's account number must be entered manually. However, this is only valid for a certain time and then expires.
• The chipTAN generator is the most convenient. This consists of a display, input keys and a slot for the customer card. It also has five optical sensors on the back. And this is how the most common generator works: In online banking, the customer enters the data for a transfer, for example. A flickering black and white graphic then appears on the screen. If the customer now holds the sensors of the generator with the card inserted to this graphic, the entered data is transferred to the device. The customer can check the recipient's account number and the amount again on the display. If he confirms the data by pressing a button, the generator creates a chipTAN. It is only valid for this one transaction.
• In addition to TAN generators, there are other methods for generating TANs. These include, for example, pushTAN and photoTAN. We explain both procedures in further practical tips.

The 7 best tips for secure online banking can be found in our next practical tip.