An apparatus for generating intermediate cryptogram data corresponding to a dynamic password for a first cryptographic scheme, the intermediate cryptogram data being suitable for display using a device designed for a second, different cryptographic scheme, the apparatus including: a communications interface for communicating with a said device; and a processor coupled to a memory, the memory storing processor control code to control the processor, when running, to: generate a dynamic password according to the first cryptographic scheme; and generate intermediate cryptogram data corresponding to said dynamic password, the intermediate cryptogram data being suitable for outputting to the said device so that, when the said device processes said intermediate cryptogram data according to the second cryptographic scheme, the said device generates data suitable for displaying said dynamic password.