Robust Secure Shield Architecture for Detection and Protection against Invasive Attacks

Invasive attacks, such as microprobing or focused-ion-beam (FIB) circuit editing are serious threats to security-related semiconductors. To ensure that there is security against invasive attacks, an effective countermeasure is to use a protective layer as a secure shield. Previous secure shield methods can be classified into one of two categories; detection circuits based on the delay difference or block ciphers. For the former, timing asymmetries caused by the capacitance of the probe are detected. The main drawback of this method is that it is highly vulnerable to chip editing by FIB equipment. FIB circuit editing can easily cripple the detection circuits of the secure shield. In contrast, the cryptographically secure shield based on the block cipher can provide strong protection against FIB circuit editing. However, it is prone to microprobing attacks because of its inability to detect the capacitance load of the probe. In this article, we propose a robust secure shield architecture against invasive attacks, including both probe attempts and the FIB circuit editing. The proposed method is based on the detection circuits with low hardware overhead and fast-analysis time and includes protection circuits to prevent information from being leaked.