CRYP internal peripheral

Applicable for

STM32MP13x lines, STM32MP15x lines

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1. Article purpose

The purpose of this article is to:

• briefly introduce the CRYP peripheral and its main features
• indicate the level of security supported by this hardware block
• explain how each instance can be allocated to the runtime contexts and linked to the corresponding software components
• explain how to configure the CRYP peripheral.

2. Peripheral overview

The CRYP peripheral provides hardware acceleration to encrypt or decrypt data using the DES, TDES or AES algorithms. It also supports multiple key sizes and chaining modes.

2.1. Features

Refer to STM32MP13 reference manuals or STM32MP15 reference manuals for the complete list of features, and to the software components, introduced below, to see which features are implemented.

2.2. Security support

2.2.1. On STM32MP13x lines 

CRYP is a secure peripheral (under ETZPC control).

2.2.2. On STM32MP15x lines 

CRYP1 is a secure peripheral (under ETZPC control).
CRYP2 is a non secure peripheral.

3. Peripheral usage and associated software

3.1. Boot time

3.1.1. On STM32MP13x lines 

CRYP could be used in ROM code during boot process for FSBL decryption.

3.1.2. On STM32MP15x lines 

CRYP peripheral is not used during boot process.

3.2. Runtime

3.2.1. Overview

3.2.1.1. On STM32MP13x lines 

CRYP instance can be allocated to:

• the Arm^® Cortex^®-A7 secure core to be controlled in OP-TEE by the CRYP OP-TEE driver

or

• The Arm^® Cortex^® -A7 non-secure for using in Linux^® with Linux Crypto framework

Chapter Peripheral assignment describes which peripheral instance can be assigned to which context.

3.2.1.2. On STM32MP15x lines 

CRYP1 instance can be allocated to:

• the Arm^® Cortex^®-A7 secure core to be controlled in OP-TEE by the CRYP OP-TEE driver

or

• The Arm^® Cortex^® -A7 non-secure for using in Linux^® with Linux Crypto framework

CRYP2 instance can be allocated to:

• the Arm^® Cortex^®-M4 to be controlled in STM32Cube MPU Package by STM32Cube CRYP driver

Chapter Peripheral assignment describes which peripheral instance can be assigned to which context.

3.2.2. Software frameworks

3.2.2.1. On STM32MP13x lines 

Domain	Peripheral	Software components		Comment
		OP-TEE	Linux
Security	CRYP	CRYP OP-TEE driver	Linux Crypto framework

3.2.2.2. On STM32MP15x lines 

Domain	Peripheral	Software components			Comment
		OP-TEE	Linux	STM32Cube
Security	CRYP	CRYP OP-TEE driver	Linux Crypto framework	STM32Cube CRYP driver

3.2.3. Peripheral configuration

The configuration is applied by the firmware running in the context to which the peripheral is assigned. The configuration can be done alone via the STM32CubeMX tool for all internal peripherals, and then manually completed (particularly for external peripherals), according to the information given in the corresponding software framework article.

3.2.4. Peripheral assignment

3.2.4.1. On STM32MP13x lines 

Click on the right to expand the legend...

STM32MP13 internal peripherals

Check boxes illustrate the possible peripheral allocations supported by STM32 MPU Embedded Software:

• ☐ means that the peripheral can be assigned (☑) to the given runtime context.
• ⬚ means that the peripheral can be assigned to the given runtime context, but this configuration is not supported in STM32 MPU Embedded Software distribution.
• ✓ is used for system peripherals that cannot be unchecked because they are statically connected in the device.

Refer to How to assign an internal peripheral to a runtime context for more information on how to assign peripherals manually or via STM32CubeMX.
The present chapter describes STMicroelectronics recommendations or choice of implementation. Additional possiblities might be described in STM32MP13 reference manuals.

Domain	Peripheral	Runtime allocation			Comment
		Instance	Cortex-A7 secure (OP-TEE)	Cortex-A7 non-secure (Linux)
Security	CRYP	CRYP	☐	☐	Assignment (single choice)

3.2.4.2. On STM32MP15x lines 

Click on the right to expand the legend...

STM32MP15 internal peripherals

Check boxes illustrate the possible peripheral allocations supported by STM32 MPU Embedded Software:

• ☐ means that the peripheral can be assigned (☑) to the given runtime context.
• ⬚ means that the peripheral can be assigned to the given runtime context, but this configuration is not supported in STM32 MPU Embedded Software distribution.
• ✓ is used for system peripherals that cannot be unchecked because they are statically connected in the device.

Refer to How to assign an internal peripheral to a runtime context for more information on how to assign peripherals manually or via STM32CubeMX.
The present chapter describes STMicroelectronics recommendations or choice of implementation. Additional possiblities might be described in STM32MP15 reference manuals.

Domain	Peripheral	Runtime allocation				Comment
		Instance	Cortex-A7 secure (OP-TEE)	Cortex-A7 non-secure (Linux)	Cortex-M4 (STM32Cube)
Security	CRYP	CRYP1	☐	☐		Assignment (single choice)
		CRYP2			☐

Cryptographic processor

Data encryption standard

Triple data encryption standard

Advanced encryption standard

First stage boot loader

Arm^® is a registered trademark of Arm Limited (or its subsidiaries) in the US and/or elsewhere.

Cortex^®

Open portable trusted execution environment

Linux^® is a registered trademark of Linus Torvalds.

Microprocessor unit

Cryptographic processor

Data encryption standard

Triple data encryption standard

Advanced encryption standard

First stage boot loader

Arm^® is a registered trademark of Arm Limited (or its subsidiaries) in the US and/or elsewhere.

Cortex^®

Open portable trusted execution environment

Linux^® is a registered trademark of Linus Torvalds.

Microprocessor unit