Abstract: A microprocessor is provided to compute a code used to detect an execution fault, using a relationship Ci=P o Fa(Di), where: Fa(Di)=E0 o . . . o Eq o . . . o ENbE-1(Di), Eq (x)=T?m,q o . . . o T?j,q o . . . o T?1,q o T?1,q(x), and T?j,q is a conditional transposition, configured by a secret parameter ?j,q, that permutes two blocks of bits B2j+1,q and B2j,q of the variable x only when the parameter ?j,q is equal to a first value, the blocks B2j+1,q and B2j,q of all of the transpositions T?j,q of the stage Eq being different from one another and not overlapping and the blocks B2j+1,q and B2j,q are placed within one and the same block of greater size permuted by a transposition of the higher stage Eq+1.

Abstract: A method for executing a machine code using a microprocessor includes, after an operation of decoding a current loaded instruction, constructing a mask from the signals generated by an instruction decoder in response to decoding of the current loaded instruction by the decoder. The constructed mask varies as a function of the current loaded instruction. Subsequently, before an operation of decoding a next loaded instruction, the next loaded instruction is unmasked using the constructed mask.

Abstract: A method for executing a function, secured by temporal desynchronization, includes when a first legitimate instruction is loaded, noting the opcode of this first legitimate instruction, then constructing a dummy instruction on the basis of this noted opcode, the dummy instruction thus constructed being identical to the first legitimate instruction except that its operands are different, then incorporating the dummy instruction thus constructed into a sequence of dummy instructions used to delay the time at which a second legitimate instruction is executed.

Abstract: A method of executing machine code using a microprocessor includes, for each datum Di, computing a code Ci using a relationship Ci=Q?(Di)=P o F?(Di), where P is a predetermined function, F? is a function defined by the following relationship: F?(Di)=T?t o . . . o T?r o . . . o T?1 o T?0(Di), and T?r is ?conditional transposition, configured by a secret parameter ?r, that permutes two blocks B1r and B2r of bits of the datum Di on the basis of the value of the parameter ?r. The method also includes computing a code Cres-t using the following relationship: Cres-t=C1 & C2 & . . . & Cn, where C1 to Cn are the codes associated with data D1 to Dn combined with one another by a Boolean operation D1 & D2 & . . . & Dn where the “&” symbol designates the Boolean operation.

Abstract: This microprocessor is configured to compute a code C1, used to detect an execution fault, using a relationship Ci=P o F?(Di), where: F?(Di)=E0 o . . . o Eq o . . . o ENbE?1(Di), Eq(x)=T?m,q o . . . o T?j,q o . . . o T?1,q o T?0,q(X), and T?j,q is a conditional transposition, configured by a secret parameter ?j,q, that permutes two blocks of bits B2j+1,q and B2j,q of the variable x only when the parameter aj,q is equal to a first value, the blocks B2j+1,q and B2j,q of all of the transpositions T?j,q of the stage Eq being different from one another and not overlapping and the blocks B2j+1,q and B2j,q are placed within one and the same block of greater size permuted by a transposition of the higher stage Eq+1.

Abstract: This method comprises: for each datum Di, computing a code Ci using a relationship Ci=Qa (Di)=P o Fa (Di), where: P is a predetermined function, Fa is a function defined by the following relationship: Fa(Di)=Tat o . . . o Tar o . . . o Ta1 o Ta0 (Di), Tar is a conditional transposition, configured by a secret parameter ar, that permutes two blocks B1r and B2r of bits of the datum Di on the basis of the value of the parameter ar, computing a code Cres-t using the following relationship: Cres-t=C1 & C2 & . . . &Cn, where C1 to Cn, are the codes associated with data D1 to Dn combined with one another by a Boolean operation D1&D2& . . . &Dn, where the “&” symbol designates the Boolean operation.

Abstract: A method for executing a machine code using a microprocessor includes, after an operation of decoding a current loaded instruction, constructing a mask from the signals generated by an instruction decoder in response to decoding of the current loaded instruction by the decoder. The constructed mask varies as a function of the current loaded instruction. Subsequently, before an operation of decoding a next loaded instruction, the next loaded instruction is unmasked using the constructed mask.

Abstract: A method for executing a function, secured by temporal desynchronization, includes when a first legitimate instruction is loaded, noting the opcode of this first legitimate instruction, then constructing a dummy instruction on the basis of this noted opcode, the dummy instruction thus constructed being identical to the first legitimate instruction except that its operands are different, then incorporating the dummy instruction thus constructed into a sequence of dummy instructions used to delay the time at which a second legitimate instruction is executed.