The Omnikey AG 5022 CL has a Software developer guide with specific example code to authenticate to a Mifare Ultralight-C card (section 5.4.3 in the guide). The guide suggests to split the 16 bytes 3DES key for the authentication into two parts, load the keys via SCardControl() into key position 0 and 1 of the reader and gives the reader the instruction to authenticate. Problem is that the reader has only 6 bytes of memory available, so I got an 0x6989 key length error back. The example code in the developer guide is meant for Mifare Classic authentication, is my impression. Not for authentication with an Ultralight-C.
Wich leaves the question open how to authenticate to an Ultralight-C card with the Omnikey 5022. Anybody who knows the trick? Or has a pointer into the right direction?