IoT Device Security the Hard(ware) way

Numerous attacks on Internet of Things (IoT) devices have shown that security cannot be neglected, even when building devices with just a few kB of memory. While it is common sense to run regular software updates and use state-of-the-art security on embedded or general purpose systems, this is often not possible with IoT devices. While many of those devices have the facilities to perform over-the-air updates, their memory and processing capabilities limit the use of state-of-the-art cryptography. Additionally, these devices often lack the capabilities to secure the cryptographic keys, the foundation on which the device's security is built, which makes them even more vulnerable to attacks. In this work, we present a pattern that allows even constrained devices to utilize state-of-the-art cryptographic functions, providing the foundation for a secure Internet of Things. The identified pattern presents the following characteristics: (i) confidentiality, by offloading the cryptographic functions and key storage; (ii) authenticity, by signing messages with the securely stored key using hash as well as signature functions, often too complex for such constrained devices on their own; (iii) integrity, a key requirement for connected sensors. As an added benefit, a faster detection of corrupted or tampered updates can also increase the availability of the system. This pattern is primarily targeted at IoT device vendors, who wish to keep their devices secure, by implementing security in hardware.