SD card security

I need the Arduino to read information from an SD card, but I do not want a user to take out my card and use it to make their own card with their own information and insert it back in.

For example, if my card has 100 names in a text file, the Arduino reads the file and prints the names to the LCD screen. I do not want them to make a new SD card with new names.

I need it to only work with the SD cards that I provide. Can anyone give suggestions or ideas on how I could do this?

Store the information in encrypted form on the SD card. Encryption libraries are available for PC and Arduino. 3DES or AES; I think that there is even a RSA library for the Arduino.

May I first ask a question before looking into Encryption libraries? Will the Encryption/Decryption process of hundreds of text files slow down the Atmaga328pu at 8MHz? I will only need to decrypt a small amount at a time then display that information on an LCD screen before moving on to the next.

Thanks

Yes, it will take time. You will have to figure that out by trial and error.

If the data comes from a PC, you can do the encryption on the PC. Leaves the decryption to the Arduino.

Thanks,

I hope to use Arduino xxtea-iot-crypt Library for decryption from the SD card.
I found this site: Online XXTEA Decrypt - Online tools
I hope to use that site for the encryption.
Has anyone used the xxtea-iot-crypt Library or that site? If so, any pointers?