ST Tackles Card Security With Microcontrollers Using BSoC and Arm SecurCore

December 06, 2021 by Abdulwaliy Oyekunle

To enhance authentication in contactless transactions through biometric system-on-card (BSoC), STMicroelectronics has recently released a family of microcontrollers based on Arm's SecurCore.

Ease of use and security are paramount in online transactions and contactless payments, especially as the world zooms in on finding more ways to secure technology. One way designers can achieve higher security for transactions is by adopting a BSoC technology.

In general, BSoC technology features a portable card size device with a fingerprint sensor and integrated circuitry. The technology captures user data (fingerprint) and stores it in a secure element.

Typical applications of the technology include access control, internet of things (IoT) solutions, and payment authentication.


An example BSoC architecture with an embedded fingerprint sensor and microcontroller in a single card.

An example BSoC architecture with an embedded fingerprint sensor and microcontroller in a single card. Image used courtesy of STMicroelectronics


Hoping to leverage its security benefits, STMicroelectronics (ST) has created a new series of microcontrollers, the ST31N, which are general-purpose microcontrollers embedded in a BSoC technology device. 

This article will discuss key things engineers would have to keep in mind while designing an efficient BSoC device and delve into the ST’s latest processor.


Requirements of a Portable Biometric System-on-Card Technology

Engineers encounter some challenges when designing a portable and efficient BSoC device. Though the main components of a BSoC device are the fingerprint sensor, a general-purpose microcontroller, and a secure element, engineers must still surmount design challenges to realize their solutions.

Overall, achieving a low power consumption is one of the aims of an engineer when designing electronic devices, especially in a BSoC device. 

Typically, a BSoC device should be designed to operate from the power tapped from energy harvesting during electromagnetic coupling. The energy harvested should also eliminate the need for an external battery.

A BSoC device promises to be useful in a wide range of applications, including ID cards, contactless transactions, badges, and so on. This large range of use cases means that more user data is anticipated to be stored in the secure element, which also means that engineers should consider storage size when designing the device. 

In addition, a general-purpose microcontroller that can run and process information during data enrollment and verification is necessary to achieve an efficient BSoC.


ArmSecure SC000 Takes the Processing Task

The new family of microcontrollers from STMicroelectronics include ST31N600, ST31N500, and ST31N400


Functional diagram of the ST31N series of microcontrollers.

Functional diagram of the ST31N series of microcontrollers. Image used courtesy of STMicroelectronics


The ST31N series features the Arm SecurCore SC000 processing core, a 32-bit reduced instruction set computer suitable for use in smartcards. 

Additionally, it features both the low power and low area from Arm Cortex M0. It also supports a memory protection unit (MPU), library protection unit, active shield, and other securing mechanisms to guard against multiple attacks.


The block diagram of the Arm SecureCore SC000 processing core.

The block diagram of the Arm SecurCore SC000 processing core. Image used courtesy of Arm


With Arm SecurCore SC000, the computation time in capturing user data (fingerprint), matching, and verification takes less time in a BSoC device that adopts the ST31N product as the microcontroller in its internal circuitry.

Apart from BSoC applications, the microcontroller is also valuable for dynamic card verification (dCVV) for e-commerce payments.

Commenting on the ST31N600, the Marketing Director in the Secure Microcontroller Division at STMicroelectronics, Laurent Degauque, says that it is a starting point for advances in smartcard security, thanks to the features that could enable easier to use and innovative authentication mechanisms for payments.