STFCF FAQ

What is STFCF?

The STM32 Flexible Crypto Framework (STFCF) middleware provides a comprehensive and flexible cryptographic solution for STM32 microcontrollers. It supports various features, cores, and configurations to meet diverse application requirements. STFCF relies on the Mbed TLS middleware for the core cryptographic features. It extends these features with additional services and wrappers adapted to STM32 products.

What external cryptographic dependencies does STFCF rely on?

STFCF depends on the Mbed TLS middleware as its main cryptographic backbone, along with third-party libraries such as STCryptoLib or HAL, and PSA drivers for secure elements and persistent storage.

How does STFCF utilize hardware and software cryptographic implementations?

STFCF supports alternative implementations of Mbed TLS using HAL for hardware acceleration and STCryptoLib for optimized software cryptography on STM32 microcontrollers.

What is the role of the Key Wrap Engine (KWE) in STFCF?

The Key Wrap Engine (KWE) is a PSA driver that uses the CCB and/or SAES peripherals to manage keys securely. It wraps, unwraps, shares, and generates keys so that users never handle keys directly.

How does STFCF support and organize multiple alternative cryptographic implementations?

STFCF uses a common switching interface to enable mixing and selecting different alternatives (such as MBEDTLS_AES_ALT with HAL and MBEDTLS_SHA256_ALT with STCryptoLib). Behind this interface, dedicated header files provide the specific implementations for HAL (handling hardware details) and STCryptoLib (software-based solutions), ensuring seamless integration with Mbed TLS.