NOR flash helps tackle IoT security concerns

BY SUNDAR RANGANATHAN, Sr. Product Marketing Manager
Micron Technology
www.micron.com

Businesses are deploying more and more connected devices to improve processes and transform operations — devices with computing and network capabilities that make decisions in real time. According to the new research from IDC, the worldwide IoT market will grow to $1.7 trillion in 2020, with a CAGR of 16.9%. Modules and sensors alone are 31.8% of that total. The growth will fuel business efficiencies and introduction of new goods and services across industries.

With such an expansion expected, one key area of concern for design engineers is security. More connected devices mean more possibilities for device hacks. There is a pressing need to secure communications, protect systems from unintentional overwrites and malicious attacks, and be able to authenticate data transfers.

Lately, we have heard some disturbing cases of hacking — hacking baby monitors, vulnerabilities of drug infusion pumps, hackers sending commands through the Jeep’s entertainment system to its dashboard functions and brakes. It is imperative to plug all areas of vulnerabilities at multiple levels of design.

The special needs of IoT

Most IoT devices are meant to be sleek and efficient. They often sense analog inputs from the environment (temperature, moisture, etc.), digitize them, and analyze the data, either on board or in the cloud. The typical device/system has sensors, MCU, flash memory, and a radio unit, in addition to other components. The flash memory is very important as it is used for code storage, device configuration, and security keys. The type of non-volatile memory depends on the application. NOR flash is popular for its reliability, security features, and low latency access — providing an ideal execute-in-place (XiP) memory for code and small amounts of data.

Preventing unauthorized access to data and IP is essential. Flash memory can offer protection against data corruption (intentional or accidental) and unauthorized copying or cloning of software/firmware. This can be achieved by implementing security solutions at multiple layers (hardware and software levels) of the architecture:

• Hardware level — security built into the flash subsystem
• Software level — security to restrict read/modify access to the flash memory

 Following are a few advanced features used to enhance security and address vulnerable areas:

• Block locking — This security feature locks block memory by setting a bit; the flash will not allow modification of its contents if this bit is not in its correct state.
• One Time Programmable (OTP) — This advanced security feature permanently locks flash blocks so they can no longer be erased or written to. OTP is commonly used to protect initialization or boot code in a system, helping to prevent corruption. It is also a useful place to store immutable data, such as RSA public keys.
• Replay Protected Monotonic Counter (RPMC) — This advanced security feature adds incremental monotonic counting to code and data storage in boot memory, preserving uniqueness and helping to make systems more resistant to rollback and replay attacks.
• Read Protection — This feature marks certain blocks to prevent reading; this protects IP or data stored in the chip.

Security for connected devices is now getting the attention it rightly deserves. There has to be a multi-tiered approach to security — at the hardware level, all interfaces, and at the application level.

NAND vs NOR flash

NAND flash stores multiple bits in series, trading off random access for density and write speed. NOR behaves more like traditional DRAM, where memory cells can be read and written individually instead of an entire block at a time and can thus be used for execute-in-place, so the code does not first have to be copied to a separate RAM cache. NOR flash features read throughput of up to 333 Mbytes/s as well as 100 ns initial access times, which enables very fast boot for critical system availability and “instant on” access. 

NOR plays a key role in IoT security. Micron Technology is collaborating with partners on IoT designs to implement security features and deliver the right NOR flash storage solution to ensure devices operate longer and securely.