Cryptographic method for protecting a key hardware register against fault attacks

The present invention relates to cryptographic method that are resistant to fault injection attacks, to protect the confidentiality and the integrity of secret keys. For that, the invention describes a method to protect a key hardware register against fault attack, this register being inside an hardware block cipher BC embedded inside an electronic component, said component containing stored inside a memory area a cryptographic key K, characterized in that it comprises following steps: A.) loading the key Kram inside said register; B.) computing a value X such as K=BC(K,X); C.) after at least one sensitive operation, computing a value V such as V=BC(K,X); D.) matching the value V with the key Kram value stored in the memory area; E.) if the matching is not ok detecting that a fault occurs.