Many banks offering HBCI require authentication using the "chipTAN" system. In this system the bank sends an challenge code for the user to enter into a code generator that uses it to generate a "Transaction Authentication Number" or TAN to validate the transaction. The challenge code can be entered by hand (already supported by GnuCash) but that is cumbersome and error-prone. The code generators can also read the number from the screen using a so-called "flicker code".

Specifications are available from https://github.com/willuhn/hbci4java/blob/master/doc/tan_hhd_uc_v14.pdf

An MIT-licensed javascript implementation is available at https://github.com/my-flow/fintex/blob/master/lib/tan/flicker_code.ex

Proposal: Retrieve the challenge code from AQBanking and open an html tab/window containing the javascript and pass it the challenge code to display.