tachograph smartcard process dsrc message

Question

Regarding the EU Commission regulation 2016/799, encrypted smart tachograph DSRC-RTMdata can be decrypted using a command called PROCESS DSRC MESSAGE.

I am trying to decrypt RTMdata and i am getting error 6A80. RTM data should be 100% ok. Everything looks straightforward but it's not working. I tried adding "MANAGE SECURITY ENVIRONMENT" (MSE : SET AT) before process dsrc message but it's not helping.

Does anybody have any experiences with this and the sequence of apdu commands to achieve this?

I have tried with:

• Select tachoG2 (00A4040C06FF534D524454) - Successfully
• Manage security environment (002241A40C800A04007F00070202030202) - Successfully
• PROCESS DSRC MESSAGE ("802A80B060" + rtm-data + "00") Unsuccessful (Response is ‘6A80’ indicates incorrect parameters in the command data field (also used in case the data objects are not sent in the specified order).)

Answer 1

The length (Lc) field is defined as

Length Lc of the subsequent data field

You are sending a length of "0x60" which also includes the "Le" field.

Your PROCESS DSRC MESSAGE should look like

"802A80B05F" + rtm-data + "00"