OTFAD: On The Fly AES-128 Decryption Driver

Overview

The MCUXpresso SDK provides a peripheral driver for On The Fly AES-128 Decryption (OTFAD) module of MCUXpresso SDK devices.

This example code shows how to decrypt ciphertext in external memory using the OTFAD driver.

Refer to the driver examples codes located at <SDK_ROOT>/boards/<BOARD>/driver_examples/otfad

Data Structures
struct	otfad_encryption_config_t
	OTFAD encryption configuration structure. More...
struct	otfad_config_t
	OTFAD configuration structure. More...

Enumerations
enum	{   kStatus_OTFAD_ResRegAccessMode = MAKE_STATUS(kStatusGroup_OTFAD, 0),   kStatus_OTFAD_AddressError = MAKE_STATUS(kStatusGroup_OTFAD, 1),   kStatus_OTFAD_RegionOverlap,   kStatus_OTFAD_RegionMiss }
	Status codes for the OTFAD driver. More...
enum	{   kOTFAD_Context_0 = 0U,   kOTFAD_Context_1 = 1U,   kOTFAD_Context_2 = 2U,   kOTFAD_Context_3 = 3U }
	OTFAD context type. More...
enum	{   kOTFAD_NRM = 0x00U,   kOTFAD_SVM = 0x02U,   kOTFAD_LDM = 0x03U }
	OTFAD operate mode. More...

Driver version
#define	FSL_OTFAD_DRIVER_VERSION   (MAKE_VERSION(2U, 1U, 1U))
	Driver version 2.1.1. More...

Initialization and deinitialization
void	OTFAD_GetDefaultConfig (otfad_config_t *config)
	OTFAD module initialization function. More...
void	OTFAD_Init (OTFAD_Type *base, const otfad_config_t *config)
	OTFAD module initialization function. More...
void	OTFAD_Deinit (OTFAD_Type *base)
	Deinitializes the OTFAD.

Status
static uint32_t	OTFAD_GetOperateMode (OTFAD_Type *base)
	OTFAD module get operate mode. More...
static uint32_t	OTFAD_GetStatus (OTFAD_Type *base)
	OTFAD module get status. More...

functional
status_t	OTFAD_SetEncryptionConfig (OTFAD_Type *base, const otfad_encryption_config_t *config)
	OTFAD module set encryption configuration. More...
status_t	OTFAD_GetEncryptionConfig (OTFAD_Type *base, otfad_encryption_config_t *config)
	OTFAD module get encryption configuration. More...
status_t	OTFAD_HitDetermination (OTFAD_Type *base, uint32_t address, uint8_t *contextIndex)
	OTFAD module do hit determination. More...

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Data Structure Documentation

struct otfad_encryption_config_t

Data Fields
bool	valid
	The context is valid or not.
bool	AESdecryption
	AES decryption enable.
uint8_t	readOnly
	read write attribute for the entire set of context registers
uint8_t	contextIndex
	OTFAD context index.
uint32_t	startAddr
	Start address.
uint32_t	endAddr
	End address.
uint32_t	key [4]
	Encryption key.
uint32_t	counter [2]
	Encryption counter.

struct otfad_config_t

Data Fields
bool	enableIntRequest
	Interrupt request enable.
bool	forceError
	Forces the OTFAD's key blob error flag (SR[KBERR]) to be asserted.
bool	forceSVM
	Force entry into SVM after a write.
bool	forceLDM
	Force entry into LDM after a write.
bool	keyBlobScramble
	Key blob KEK scrambling.
bool	keyBlobProcess
	Key blob processing.
bool	startKeyBlobProcessing
	key blob processing is initiated
bool	restrictedRegAccess
	Restricted register access enable.
bool	enableOTFAD
	OTFAD has decryption enabled.

Macro Definition Documentation

#define FSL_OTFAD_DRIVER_VERSION   (MAKE_VERSION(2U, 1U, 1U))

Enumeration Type Documentation

anonymous enum

Enumerator
kStatus_OTFAD_ResRegAccessMode	Restricted register mode.
kStatus_OTFAD_AddressError	End address less than start address.
kStatus_OTFAD_RegionOverlap	the OTFAD does not support any form of memory region overlap, for system accesses that hit in multiple contexts or no contexts, the fetched data is simply bypassed
kStatus_OTFAD_RegionMiss	For accesses that hit in a single context, but not the selected one.

anonymous enum

Enumerator
kOTFAD_Context_0	context 0
kOTFAD_Context_1	context 1
kOTFAD_Context_2	context 2
kOTFAD_Context_3	context 3

anonymous enum

Enumerator
kOTFAD_NRM	Normal Mode.
kOTFAD_SVM	Security Violation Mode.
kOTFAD_LDM	Logically Disabled Mode.

Function Documentation

void OTFAD_GetDefaultConfig

(

otfad_config_t *

config

)

Parameters

config

OTFAD configuration.

void OTFAD_Init	(	OTFAD_Type *	base,
		const otfad_config_t *	config
	)

Parameters

base	OTFAD base address.
config	OTFAD configuration.

static uint32_t OTFAD_GetOperateMode ( OTFAD_Type *  base )

inlinestatic

Parameters

base	OTFAD base address.

static uint32_t OTFAD_GetStatus ( OTFAD_Type *  base )

inlinestatic

Parameters

base	OTFAD base address.

status_t OTFAD_SetEncryptionConfig	(	OTFAD_Type *	base,
		const otfad_encryption_config_t *	config
	)

Parameters

base	OTFAD base address.
config	encryption configuration.

Note: if enable keyblob process, the first 256 bytes external memory is use for keyblob data, so this region shouldn't be in OTFAD region.

status_t OTFAD_GetEncryptionConfig	(	OTFAD_Type *	base,
		otfad_encryption_config_t *	config
	)

Parameters

base	OTFAD base address.
config	encryption configuration.

Note: if enable keyblob process, the first 256 bytes external memory is use for keyblob data, so this region shouldn't be in OTFAD region.

status_t OTFAD_HitDetermination	(	OTFAD_Type *	base,
		uint32_t	address,
		uint8_t *	contextIndex
	)

Parameters

base	OTFAD base address.
address	the physical address space assigned to the QuadSPI(FlexSPI) module.
contextIndex	hitted context region index.

Returns

status, such as kStatus_Success or kStatus_OTFAD_ResRegAccessMode.