METHOD TO PREVENT REPLAY ATTACK

The method is performed by a system (100) includingi) a secure processing sub-system (300) having an internal non-volatile memory (303),ii) a non-volatile memory (400) that is external to the secure processing sub-system (300).During each power cycle where data stored in the external non-volatile memory is updated, the secure processing sub-system executes a transaction by:. writing a first transaction data marking the start of the transaction in the internal non-volatile memory upon a first update of the data within the power cycle, and. at the end of the power cycle, writing a second transaction data marking the end of said transaction to the internal non-volatile memory.At the beginning of any power cycle, the secure processing sub-system (300). checks if a transaction is still pending in the internal non-volatile memory (303); and. if a transaction is still pending, prevents to use the data stored in the external non-volatile memory (400).