Settlement terminal and method of protecting data stored in the settlement terminal against tampering

A method of protecting data stored in a settlement terminal against tampering, wherein the settlement terminal includes a card reader, a settlement processing unit including a processor programmed to carry out a settlement process using information acquired through the card reader and a tampering detection process, and a storage device in which a first set of programs is stored after encryption by a first key and a second set of programs is stored after encryption by a second key, each set of programs including a first program for operating the card reader, and a second program for carrying out the settlement process, said method comprising:

• performing a tampering detection process;
• upon detection of tampering, notifying an external terminal of the tampering;
• and
• upon receiving an update instruction from the external terminal, updating a current set of programs used for operating the card reader and carrying out the settlement process from the first set to the second set.