SECURE INTEGRATED CIRCUIT COMPRISING MEANS FOR DISCLOSING COUNTERPART MASK VALUES
An integrated circuit includes a communication interface circuit, a cryptographic algorithm, a countermeasure configured to protect the cryptographic algorithm against side-channel attacks, and a mask generator configured to provide the countermeasure with mask values. The integrated circuit is configured to execute a specific command requiring the disclosure of mask values used by the countermeasures to protect the cryptographic algorithm during a cryptographic session, and, in response to such a command, to send the mask values through the communication interface circuit.
1 . An integrated circuit comprising:
a communication interface circuit;
a cryptographic algorithm;
a countermeasure configured to protect the cryptographic algorithm against side-channel attacks; and
a mask generator configured to provide the countermeasure with mask values,
wherein the integrated circuit is configured to execute a specific command requiring the disclosure of mask values used by the countermeasure to protect the cryptographic algorithm during a cryptographic session, and, in response to the specific command, to send the mask values through the communication interface circuit.
2 . The integrated circuit according to claim 1 , wherein the mask generator is a random or pseudo-random mask generator configured to:
store in a secure memory, during a cryptographic session, mask values used by the countermeasure to protect the cryptographic algorithm, and
in response to the specific command, read the mask values in the secure memory.
3 . The integrated circuit according to claim 1 , wherein the mask generator is configured to generate mask values from a deterministic sequence number, and the integrated circuit is configured to, in response to the specific command, regenerate, via the mask generator, mask values used during a cryptographic session.
4 . The integrated circuit according to claim 1 , configured to count a number of times the specific command was previously executed, and to not execute the specific command if the specific command has been previously executed N times.
5 . The integrated circuit according to claim 4 , configured to perform a security action if the specific command is received after having been previously executed N times.
6 . The integrated circuit according to claim 5 , configured to permanently lock if the specific command is received after having been previously executed N times.
7 . The integrated circuit according to claim 4 , wherein the number N of times the specific command is permitted to be executed is defined by a parameter securely stored in the integrated circuit.
8 . The integrated circuit according to claim 4 , configured so that the number N of times the specific command is permitted to be executed is lower than an estimated number of times that would be necessary for an attacker knowing the mask values to successfully carry out a side-channel attack of the cryptographic algorithm.
9 . The integrated circuit according to claim 4 , further comprising a test mode in which the number of times the specific command is permitted to be executed is not limited.
10 . A handheld device comprising an integrated circuit according to claim 1 .
11 . A method for carrying out a cryptographic session in an integrated circuit including a cryptographic algorithm, a countermeasure configured to protect the cryptographic algorithm against side-channel attacks, and a mask generator configured to provide the countermeasure with mask values, the method comprising:
receiving a specific command requiring the disclosure of mask values used by the countermeasures to protect the cryptographic algorithm during the cryptographic session, and
in response to the specific command, sending the mask values.
12 . The method according to claim 11 , further comprising:
storing in a secure memory, during the cryptographic session, random or pseudo-random mask values used by the countermeasures to protect the cryptographic algorithm, and
in response to the specific command, reading the mask values in the secure memory.
13 . The method according to claim 11 , further comprising:
during the cryptographic session, generating mask values from a deterministic sequence number, and
in response to the specific command, regenerating the mask values via the deterministic sequence number.
14 . The method according to claim 11 , further comprising counting a number of times the specific command was previously executed, and not executing the specific command if the specific command has been previously executed N times.
15 . The method according to claim 14 , further comprising performing a security step if the specific command is received after having been previously executed N times.
16 . The method according to claim 15 , further comprising permanently locking the integrated circuit if the specific command is received after having been previously executed N times.
17 . The method according to claim 14 , further comprising determining the number N of times the specific command is permitted to be executed such that N is lower than an estimated number of times that would be necessary for an attacker knowing the mask values to successfully carry out a side-channel attack of the cryptographic algorithm.