Secret key cryptographic process for protecting a computer system against attacks by physical analysis

A process for implementing a standard cryptographic calculation process that uses a secret key to protect a computer system against attacks by physical analysis, wherein said standard cryptographic process produces a standard final value, comprising:

• a) separating the standard cryptographic calculation process into a plurality of distinct calculation process parts,
• b) executing the distinct calculation process parts in parallel to produce partial intermediate variables distinct from any intermediate variables produced using the standard cryptographic calculation;
• and
• c) reconstructing a final value that is identical to the standard final value obtained by the standard cryptographic calculation without a separation from said distinct partial intermediate variables whereby the computer system is protected against attacks by physical analysis.