Issues accessing emulated Mifare Classic chip

This article describes issues regarding reading and writing an emulated Mifare Classic chip when using OMNIKEY 5x21 CL or OMNIKEY 5x22 CL readers in Nexus Card SDK. The article also describes the solution.

The Mifare Classic emulation is not 100% compatible with real Mifare Classic especially regarding its proprietary protocol. This can cause errors.

For OMNIKEY 5x21 CL readers, accessing (read/write) an emulated Mifare Classic chip results into error code 0x6986 and the following message "Reason for this error is probably a MIFARE EMULATING CHIP that is not supported by default.".
For OMNIKEY 5x22 CL readers, accessing (read/write) an emulated Mifare Classic chip may result into a not responding reader, thus only a power off/on will recover it.

Solution:

HID offers a free tool, called HID OMNIKEY Workbench. With this tool you can enable/disable the so-called Mifare Emulation Mode (for the OMNIKEY 5x21 CL readers) respective mifarePreferred (for the 5x22 CL readers). The standard setting for both is disabled.

One of the last Workbench version which supports both above mentioned reader generations seems to be version 1.8.1.955. Newer versions won't (fully) support the old OMNIKEY 5x21 readers.

Step-by-step instruction

Activate settings for the 5x21 CL readers

Start the Workbench.
On the left, select the OMNIKEY CardMan 5x21-CL.
On the left, select Reader Settings.
From the right tabs, select Special Options.
Enable Mifare Emulation Mode.
Click Apply and close the Workbench.
Disconnect the reader for some seconds and then reconnect it.
Now the reader will support a real Mifare Classic and also the emulated one of e.g. CardOS DI V5.3.

Activate settings for the 5x22 CL readers

Start the Workbench.
On the left, select the HID Global OMNIKEY 5x22CL.
On the left, select Reader Settings.
From the right tabs, select Card configuration.
Enable mifarePreferred.
Click Apply settings and close the Workbench.
Now the reader will support a real Mifare Classic and also the emulated one of e.g. CardOS DI V5.3.

After the settings

After these adjustments, both Mifare Classic variants, the real and the emulated one, can be encoded and the settings also remain after a reboot of the system.

the OMNIKEY 5x21 series reads the related setting from the Windows registry, verified with an OMNIKEY 5421
the OMNIKEY 5x22 series reads the related setting from its EEPROM, verified with an OMNIKEY 5122 Reader Board