In most safety-critical systems, the robustness and the confidentiality of the application code are crucial. Such code is generally stored into Non-Volatile Memories (NVMs) that are prone to faults (e.g., due to radiation effects). Unfortunately, faults affecting the instruction code result very often into Silent Data Corruption (SDC). This condition lets faults remain undetected and it can lead to undesiderable errors that may compromise the system functionality. Thus, it is desirable that the system is able to detect faults affecting the code memory. To overcome this issue, designers often resort to expensive error detection/correction mechanisms. Furthermore, they also adopt memory encryption techniques to prevent unauthorized, hence malicious, access to the code or to protect it from any unauthorized copy. In this paper, we show that the presence of memory encryption alone is able to strongly reduce the probability of SDC, without the need of implementing expensive error detection.We have performed some experiments on the OpenRISC1200 microprocessor in order to evaluate the impact on reliability stemming from different encryption methods.

Nowadays, many electronic systems store valuable Intellectual Property (IP) information inside Non-Volatile Memories (NVMs). Designers widely use encryption mechanisms to enhance the integrity of such IPs and protect them from any unauthorized access or modification. At the same time, often such IPs are critical from a reliability standpoint. Thus, dedicated techniques are employed to detect possible reliability threats (e.g., transient faults affecting the NVM content). The weights of a neural network (NN) model (e.g., integrated into an object detection system for autonomous driving or robotics) are typical examples of precious IP items. Indeed, NN weights often constitute proprietary data, stemming from an extensive and costly training process; moreover, their correctness is key for the NN to work reliably. In this article, we explore the capability of encryption mechanisms to ensure protection from both reliability threats. In particular, we assess, via extensive fault injection campaigns, the capability of different memory encryption schemes -usually used only for security purposes -to detect faults and thus, enhance the reliability of the system. Experimental results show that by cleverly choosing the proper encryption scheme, it is possible to achieve very high fault detection rates (greater than 99%) with respect to Multiple Bit Upsets. The gathered results pave the way to the integration of reliability and security mechanisms to achieve better results with lower costs.

Nowadays, many electronic systems store valuable Intellectual Property (IP) information inside Non-Volatile Memories (NVMs). Therefore, encryption mechanisms are widely used in order to protect such information from being stolen or modified by human attacks. Encryption techniques can be used for protecting the application code, or sensitive sets of data in the NVM. In particular, in machine-learning applications, the weights of an Artificial Neural Network (ANN) represent a highly valuable IP stemming from long time invested in training the system along the development phase. On the other side, systems implementing ANN applications are increasingly used in safety-critical domains (e.g., autonomous driving), where a high reliability level is required. In a previous paper, we have shown that encryption techniques, applied to the application code of generic systems, provide a significantly higher error detection rate. In this paper, we focus on an ANN application and we evaluate the detection rate induced by encryption mechanisms for transient faults possibly impacting the ANN weights. We performed experiments on a pre-trained ANN, whose weights represent the sensitive IP of our system. We executed fault injection campaigns to evaluate the ANN resilience when different encryption methods are used. Experimental results showed that the presence of specific encryption mechanisms alone induces high fault detection rates in such applications. This may allow the designer to consider security and safety mechanisms together, achieving the same results with lower costs.

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