Side-channel attacks exploit power consumption, execution time, or any other physical effect caused by an implementation. Our work focuses on timing attacks (side-channel attacks exploiting only execution time). There are already several countermeasures to prevent or limit timing attacks, either on the hardware part or on the software part. However, these security mechanisms are working often separately from each other. The software part only knows the functional behavior of the hardware, but with little knowledge of the micro-architecture details, and the hardware does not know the security expected by the software. The goal of our Ph.D. is to establish a contract between the hardware and the software. This contract would allow cooperation between them to have better control regarding timing security and achieve full resistance against timing attacks at a minimal cost.