New AMBA Specification Extends Security to Embedded Design: AMBA 5 AHB5

The amount of data we generate is growing exponentially. Gartner has predicted that in 2015 the global mobile data traffic will be a total of 52 billion terabytes, an increase of 59 percent on 2014. It’s a staggering number that is driven not just by the continuation of the mobile revolution, but the next wave of connected devices all around us, constantly recording, analyzing and sending data across the network. All of the connected devices mean that the network has grown phenomenally fast.

However a network is only as strong as the weakest access point. We have seen with many high profile examples this year of how connected devices can be hacked. WIRED had a standout example, where two people gained control of a Jeep Grand Cherokee remotely through the internet connection port, and were able to do whatever they wanted with the car, including steering and engine control. It shows that the integrity of an entire system can be compromised if a hacker or someone with malevolent intent gains control of any access point. All of this adds up to a situation where, for the next generation of connected devices to be successful, they need to have an increased level of security from a system perspective.

The most likely points of attack in a system are the smallest microcontrollers that gather and process data at the endpoint, due to their wide proliferation. It is also by far the most plentiful type of connected device as there are billions in the world, many of which use the ARM® architecture. ARM v8-M is the latest architectural specification from ARM for Cortex-M processors that brings significant improvements in security provisions, lower latency and increased scalability.

Alongside ARMv8-M is a new AMBA® specification, AMBA 5 AHB5, which is an open interface protocol for embedded SoCs. It is an extension of the previous generation AHB and AHB-Lite AMBA specifications for embedded devices. It is available to download for free under licence at ARM.com.

The integration of TrustZone™ technology with both architectural specifications means that ARM’s security solution is now available for embedded designers across the entire system, fortifying the security of microcontrollers and embedded SoCs. Security at a hardware level makes it easier to ensure the safety of our data.

Together, ARMv8-M and AHB5 enable enhanced connected, intelligent and secure devices, extending the market for embedded devices. Some of the key areas of improvement in the architectural spec are security provisions, lower latency and increased scalability.

AMBA 5 AHB5 Extends Security to the System

The AHB 5 specification extends security from the processor to the entire system. AHB5 complements the ARMv8-M architecture to extend the TrustZone security foundation from the processor to the system, enabling trust within an SoC. ARMv8-M and AHB5 offer designers a standard on which they can create secure systems through the provision of secure and non-secure transactions.

AMBA 5 AHB5 Brings New Features

Extended memory types: AHB5 has additional memory types to support more complex systems. The AHB-Lite spec is the most widely-used open interface protocol for low-latency embedded designs, AHB5 enhances and extends this specification to address the security needs of the next generation of embedded SoCs. It enhances support for more complex systems, as well as easing integration of Cortex®-A & Cortex-M based systems in an SoC.

Secure transfers: Borrowing from the TrustZone methodology, the interface indicates whether a transaction is considered Secure or Non-Secure based on the source and identification protocols. Secure transactions can only be generated by Secure software or, in cases of testing, an authorised debugger. The integration of software into the specification at the grassroots, architectural level means that it is far easier to build a system that is tightly secure.

Exclusive transfers: Support semaphore-type operations.

Updated features

Multiple slave select: Single slave interface provides multiple logical interfaces and offers area efficiency.

Single-copy and multi-copy atomicity: Guarantees write to the same location are observed in the same order by all agents. Enable scaling to multiple cores.

User signalling: Allows for user extensions and consistency with AXI specification

In order to get the whole system to work, the hardware system architecture requires:

• An on-chip bus protocol and bus infrastructure components that support sideband signal for indication of the transfer type (secure or non-Secure).
• Various bus infrastructure components to support partitioning of memory spaces in memory components, and to block non-secure accesses to secure memories.
• Optional peripheral access management to decide which peripherals are secure-accesses only and which are accessible by non-secure transfers. In some systems such security management could be hard wired.

Embedded designers looking to develop on the ARM v8-M architecture already have some of the important parts of the SoC design puzzle solved. AMBA 5 AHB5 is a new interface specification that is available to download now for free. It builds upon the most widely used open protocol for embedded designs and enhances the scalability and security of SoCs that will power the connected technology all around us.

What do you think about the latest announcement from ARM? What impact do you think it will have on the future of system design?