1. Article purpose[edit | edit source]
The purpose of this article is to:
- briefly introduce the PKA peripheral and its main features,
- indicate the peripheral instances assignment at boot time and their assignment at runtime (including whether instances can be allocated to secure contexts),
- list the software frameworks and drivers managing the peripheral,
- explain how to configure the peripheral.
2. Peripheral overview[edit | edit source]
The PKA (public key accelerator) peripheral is used to ease computation of cryptographic public key primitives, specifically those related to RSA, Diffie-Hellmann or ECC (elliptic curve cryptography) over GF(p) (Galois fields).
Refer to the STM32MP13 reference manuals for the complete list of features, and to the software frameworks and drivers, introduced below, to see which features are implemented.
3. Peripheral usage[edit | edit source]
This chapter is applicable in the scope of the OpenSTLinux BSP running on the Arm® Cortex®-A processor(s), and the STM32CubeMPU Package running on the Arm® Cortex®-M processor.
3.1. Boot time assignment[edit | edit source]
3.1.1. On STM32MP13x lines 
[edit | edit source]
The PKA peripheral is a boot device, it is used for signature verification on secure boot processing.
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to expand or collapse the legend...
| Domain | Peripheral | Boot time allocation | Comment
| |||
|---|---|---|---|---|---|---|
| Instance | Cortex-A7 secure (ROM code) |
Cortex-A7 secure (TF-A BL2) |
Cortex-A7 non-secure (U-Boot) | |||
| Security | PKA | PKA | ✓ | ☑ | ⬚ | Assignment is mandatory only for secure boot |
3.1.2. On STM32MP2 series[edit | edit source]
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| Domain | Peripheral | Boot time allocation | Comment
| |||
|---|---|---|---|---|---|---|
| Instance | Cortex-A35 secure (ROM code) |
Cortex-A35 secure (TF-A BL2) |
Cortex-A35 non-secure (U-Boot) | |||
| Security | PKA | PKA | ✓ | ☑ | ⬚ | Assignment is mandatory only for secure boot |
3.2. Runtime assignment[edit | edit source]
3.2.1. On STM32MP13x lines [edit | edit source]
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| Domain | Peripheral | Runtime allocation | Comment
| ||
|---|---|---|---|---|---|
| Instance | Cortex-A7 secure (OP-TEE) |
Cortex-A7 non-secure (Linux) | |||
| Security | PKA | PKA | ☐ | ⬚ | Assignment (single choice) |
3.2.2. On STM32MP25x lines [edit | edit source]
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| Domain | Peripheral | Runtime allocation | Comment
| |||||
|---|---|---|---|---|---|---|---|---|
| Instance | Cortex-A35 secure (OP-TEE / TF-A BL31) |
Cortex-A35 non-secure (Linux) |
Cortex-M33 secure (TF-M) |
Cortex-M33 non-secure (STM32Cube) |
Cortex-M0+ (STM32Cube) | |||
| Security | PKA | PKA | ☐OP-TEE | ⬚ | ☐ | ⬚ | ||
4. Software frameworks and drivers[edit | edit source]
Below are listed the software frameworks and drivers managing the PKA peripheral for the embedded software components listed in the above tables.
- OP-TEE: PKA driver through the ECC framework
- TF-A BL2: TF-A Crypto Library
5. How to assign and configure the peripheral[edit | edit source]
The peripheral assignment can be done via the STM32CubeMX graphical tool (and manually completed if needed).
This tool also helps to configure the peripheral:
- partial device trees (pin control and clock tree) generation for the OpenSTLinux software components,
- HAL initialization code generation for the STM32CubeMPU Package.
The configuration is applied by the firmware running in the context in which the peripheral is assigned.
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