Virtualization, security and trusted execution environments are all trending topics in the new age of ubiquitous connectivity. However, there is a lot of confusion over how these technologies work together and their role in the overall mobile and embedded computing ecosystem.

Luckily, Mike Borza, CTO of the Synopsys-owned Elliptic Technologies has published an extremely insightful whitepaper that clarifies how secure virtualization works in the context of trusted execution environments (TEEs).

Secure virtualization

Virtualization is not only a big part of data centers and enterprise networking, but it is also becoming an important requirement for mobile devices and IoT nodes. Consumer electronics, automotive and IoT markets all look to virtualization for a straightforward way to provide secure separation of resources from each other.

Most of these markets use all-in-one chips (SoCs) which integrate several multicore processors (CPUs, GPUs, VPUs, ISPs, DSPs, RPUs etc.). This approach to system design means that virtualization must be implemented throughout the entire SoC architecture to ensure secure separation between all on-chip components; the author calls this concept secure virtualization.

MIPS P5600 VirtualizationMIPS CPUs support multiple virtual machines (VMs)

The benefits of implementing these security technologies are huge: secure virtualization allows TEEs to be developed for specific applications, isolated from other TEEs that may be present in a device. This isolation prevents a security weakness or breach in one domain from compromising the security of other domains. By adopting an architecture that supports multiple TEEs, developers can continue to add new security domains to devices that are already in the field.

The security model

Any platform can be seen as a collection of hardware and software systems that execute multiple virtual machines (VMs). Each virtual machine creates an environment in which applications or operating systems may run. VMs may run independently of each other or they can collaborate on particular computing tasks. The whitepaper presents several examples of how this functionality can be implemented in a mobile device when it comes to streaming media or making online payments.

If secure separation is provable and enforceable, it becomes the basis for creating a TEE in a VM. This principle is illustrated below:

 Multiple secure VMs provide separate security domains for different applicationsMultiple secure VMs provide separate security domains for different applications

Secure solutions require full software and hardware support

The whitepaper also presents the general architecture of a hypervisor and the software stack that needs to be built to support it; then the article goes on to describe the complexity of the SoC architecture.

The author concludes that secure virtualization has great benefits for embedded devices and offers more robust, reliable and secure systems. Even better, the methodologies described in the whitepaper are fully compatible with the already well-established principles described by organizations like GlobalPlatform.

It will be exciting to see these new methods being deployed in next generation devices that require a holistic approach to security. To accelerate this, Elliptic Technologies joined a working group initiated by the prpl foundation which focuses on creating an open framework that addresses next-generation security requirements of connected devices.

Interested in how system designers everywhere can use the technologies mentioned above to bring more secure and reliable devices to end users? Make sure you read about our OmniShield security technology and its wide range of applications.

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