Cryptographic method for protecting a key hardware register against fault attacks

A hardware block cipher comprising a set of instructions, which when loaded into said block cipher, causes the block cipher to carry out the cryptographic method to protect a key hardware register against fault attack comprising instructions to cause the hardware block cipher to protect the key hardware register by:

• A. loading the key Kram inside said register,
• B. computing a value X wherein the value X is uniquely defined such that application of the block cipher to the value X using the key K, the resulting cipher text has exactly a value equal to the key K, i.e.,
• K=BC(K,X), wherein key K is the key Kram loaded inside said register,
• C. after at least one sensitive operation, computing a value V such as V=BC(K,X),
• D. comparing the value V with the key Kram value stored in the memory area,
• E. if the value V is not equal to the key Kram, raising an error that a fault has occurred.

An electronic component comprising an embedded hardware block cipher having a set of instructions, which when loaded into said block cipher, causes the block cipher to carry out the cryptographic method to protect a key hardware register against fault attack comprising instructions to cause the hardware block cipher to protect the key hardware register by:

• A. loading the key Kram inside said register,
• B. computing a value X wherein the value X is uniquely defined such that application of the block cipher to the value X using the key K, the resulting cipher text has exactly a value equal to the key K, i.e.,
• K=BC(K,X), wherein key K is the key Kram loaded inside said register,
• C. after at least one sensitive operation, computing a value V such as V=BC(K,X),
• D. comparing the value V with the key Kram value stored in the memory area,
• E. if the value V is not equal to the key Kram, raising an error that a fault has occurred.