CardExchange DESFire UID Manipulation

Modified on Wed, 12 Jul, 2023 at 2:26 PM

To write a Python script that does the DESFire UID manipulation, please refer to the steps below:

Step 1:

Create a new MIFARE DESFire definition, according to your preferences.

Step 2:

Insert a Text box on the card.

Step 3:

A window will pop-up and you change the “Fixed Value” to “Script”.

Step 4:

After you change the “Fixed Value” to “Script” you define it as uid_var. Then another window will appear, it’s where you attribute the uid_var the value of UID. Then Press Ok.

Step 5:

Your Insert new object window should look as the image that follows and then you click on the arrow on the left side of varuid.

Step 6:

Select MIFARE DESFire UID.

Step 7:

Go to functions.

On the Functions tab insert the Python Script.

Example: Last 8 Numbers

uid = uid_var

str = str(uid)

x = len(str)

uid_var = str[x-8:x]

Code explanation:

uid = uid_var
str = str(uid)
sizeOfUid = len(str)
numberOfChars = 8
uid_var = str[sizeOfUid-numberOfChars:sizeOfUid]

Close the properties window, save the changes made and you should have the expected result.