Security is one of the most important features that a system must provide. Depending on the application of the target device, different threats should be considered at design time. However, the attack space is vast. Hence, it is difficult to decide what components to protect, what level of protection they require and how efficient they are in the field. This paper tries to close this validation gap for power based side channel attacks by providing a fast and reliable leakage assessment at design time that can be used to perform design space exploration for security. To accomplish our goal, we use Generative Adversarial Networks (GAN) to generate reliable power traces for hardware implementations at design time that are subsequently used to assess the leakage of the design. As a case study, we validated our framework against three AES implementations (i.e., unprotected, masked-protected, and balanced protected). In comparison to CAD-based scenarios, our findings show that the GAN model creates extremely reliable power traces in terms of attackability and leakage assessment. In addition, it is approximately 120 times quicker than CAD tools with respect to trace generation.@en