Entropy-Shield:Side-Channel Entropy Maximization for Timing-based Side-Channel Attacks

The hardware systems have experienced a plethora of side-channel attacks (SCAs) in recent years with cache-based SCAs being one of the dominant threats. The SCAs exploit the architectural caveats, which invariably leak essential information during an application's execution. Shutting down the side-channels is not a feasible approach due to various restrictions, such as architectural changes and complexity. To overcome such concerns and protect the data integrity, we introduce Entropy-Shield in this work. The proposed Entropy-Shield aims to maximize the entropy in the leaked side-channel information rather than attempting to close the side-channels. To achieve this, the proposed Entropy-Shield introduces carefully and sensibly crafted perturbations into the victim application, thereby increasing the entropy of the information obtained by the attacker to deduce the secret key, while the information being observed looks legit yet futile. This methodology has been successfully tested on cache targeted SCAs such as Flush+Reload and Flush+Flush and the key information retrieved by the attacker is shown to be ultimately futile, indicating the success of proposed Entropy-Shield.