Detailed Description

AESECB driver header.

============================================================================

Warning: This is a beta API. It may change in future releases.

Overview

The Electronic Code Book (ECB) mode of operation is a generic encryption block cipher mode. It can be used with any block cipher. AESECB encrypts or decrypts one or multiple blocks of plaintext or ciphertext using the Advanced Encryption Standard (AES) block cipher. Each input block is individually encrypted or decrypted. This means that blocks of ciphertext can be decrypted individually and out of order. Encrypting the same plaintext using the same key yields identical ciphertext. This raises several security issues. For this reason, it is not recommended that ECB be used unless interfacing with unupdatable legacy systems or where a standard specifies its use. Better alternatives would be an authenticated encryption with associated data (AEAD) mode such as CCM or GCM.

The AES key is a shared secret between the two parties and has a length of 128, 192, or 256 bits.

Usage

Before starting an ECB operation

Before starting an ECB operation, the application must do the following:

Call AESECB_init() to initialize the driver
Call AESECB_Params_init() to initialize the AESECB_Params to default values.
Modify the AESECB_Params as desired
Call AESECB_open() to open an instance of the driver
Initialize a CryptoKey. These opaque datastructures are representations of keying material and its storage. Depending on how the keying material is stored (RAM or flash, key store, key blob), the CryptoKey must be initialized differently. The AESECB API can handle all types of CryptoKey. However, not all device-specific implementions support all types of CryptoKey. Devices without a key store will not support CryptoKeys with keying material stored in a key store for example. All devices support plaintext CryptoKeys.
Initialize the AESECB_Operation using AESECB_Operation_init() and set all length, key, and buffer fields.

Starting an ECB operation

The AESECB_oneStepEncrypt and AESECB_oneStepDecrypt functions do an ECB operation in a single call. They will always be the most highly optimized routines with the least overhead and the fastest runtime. Since ECB plaintext blocks are simply encrypted with the block cipher block by block, there is no difference in the ciphertext between encrypting two blocks in one go or encypting each block individually.

After the ECB operation completes

After the ECB operation completes, the application should either start another operation or close the driver by calling AESECB_close()

AESECB Driver Configuration

In order to use the AESECB APIs, the application is required to provide device-specific AESECB configuration in the Board.c file. The AESECB driver interface defines a configuration data structure:

typedef struct AESECB_Config_ {
    void                   *object;
    void          const    *hwAttrs;
} AESECB_Config;

The application must declare an array of AESECB_Config elements, named AESECB_config[]. Each element of AESECB_config[] must be populated with pointers to a device specific AESECB driver implementation's driver object and hardware attributes. The hardware attributes define properties such as the AESECB peripheral's base address. Each element in AESECB_config[] corresponds to an AESECB instance and none of the elements should have NULL pointers. There is no correlation between the index and the peripheral designation (such as AESECB0 or AESECB1). For example, it is possible to use AESECB_config[0] for AESECB1. Multiple drivers and driver instances may all access the same underlying hardware. This is transparent to the application. Mutual exclusion is performed automatically by the drivers as necessary.

Because the AESECB configuration is very device dependent, you will need to check the doxygen for the device specific AESECB implementation. There you will find a description of the AESECB hardware attributes. Please also refer to the Board.c file of any of your examples to see the AESECB configuration.

AESECB Parameters

The AESECB_Params structure is passed to the AESECB_open() call. If NULL is passed for the parameters, AESECB_open() uses default parameters. An AESECB_Params structure is initialized with default values by passing it to AESECB_Params_init().

Examples

### Encyption of multiple plaintext blocks in blocking mode #

#include <ti/drivers/AESECB.h>
#include <ti/drivers/types/cryptoKey/CryptoKey_Plaintext.h>
...
AESECB_Handle handle;
CryptoKey cryptoKey;
int_fast16_t encryptionResult;
uint8_t plaintext[] = {0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96,
                       0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
                       0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c,
                       0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51};
uint8_t ciphertext[sizof(plaintext)];
uint8_t keyingMaterial[16] = {0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6,
                              0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c}
handle = AESECB_open(0, NULL);
if (handle == NULL) {
    // handle error
}
CryptoKeyPlaintext_initKey(&cryptoKey, keyingMaterial, sizeof(keyingMaterial));
    AESECB_Operation operation;
    AESECB_Operation_init(&operation);
    operation.key               = &cryptoKey;
    operation.input             = plaintext;
    operation.output            = ciphertext;
    operation.inputLength       = sizeof(plaintext);
encryptionResult = AESECB_oneStepEncrypt(handle, &operation);
if (encryptionResult != AESECB_STATUS_SUCCESS) {
    // handle error
}
// The resultant ciphertext should be:
// 0x3a, 0xd7, 0x7b, 0xb4, 0x0d, 0x7a, 0x36, 0x60,
// 0xa8, 0x9e, 0xca, 0xf3, 0x24, 0x66, 0xef, 0x97,
// 0xf5, 0xd3, 0xd5, 0x85, 0x03, 0xb9, 0x69, 0x9d,
// 0xe7, 0x85, 0x89, 0x5a, 0x96, 0xfd, 0xba, 0xaf
AESECB_close(handle);

Single call ECB decryption in callback mode

#include <ti/drivers/AESECB.h>
#include <ti/drivers/cryptoutils/cryptokey/CryptoKeyPlaintext.h>
...
uint8_t ciphertext[]                    = {0xf3, 0xee, 0xd1, 0xbd, 0xb5, 0xd2, 0xa0, 0x3c,
                                           0x06, 0x4b, 0x5a, 0x7e, 0x3d, 0xb1, 0x81, 0xf8};
uint8_t keyingMaterial[32]              = {0x60, 0x3d, 0xeb, 0x10, 0x15, 0xca, 0x71, 0xbe,
                                           0x2b, 0x73, 0xae, 0xf0, 0x85, 0x7d, 0x77, 0x81,
                                           0x1f, 0x35, 0x2c, 0x07, 0x3b, 0x61, 0x08, 0xd7,
                                           0x2d, 0x98, 0x10, 0xa3, 0x09, 0x14, 0xdf, 0xf4};
uint8_t plaintext[sizeof(ciphertext)];
// The plaintext should be the following after the decryption operation:
// 0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96,
// 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
void ecbCallback(AESECB_Handle handle,
                 int_fast16_t returnValue,
                 AESECB_Operation *operation,
                 AESECB_OperationType operationType) {
    if (returnValue != AESECB_STATUS_SUCCESS) {
        // handle error
    }
}
AESECB_Operation operation;
void ecbStartFunction(void) {
    AESECB_Handle handle;
    AESECB_Params params;
    CryptoKey cryptoKey;
    int_fast16_t decryptionResult;
    AESECB_Params_init(&params);
    params.returnBehavior = AESECB_RETURN_BEHAVIOR_CALLBACK;
    params.callbackFxn = ecbCallback;
    handle = AESECB_open(0, &params);
    if (handle == NULL) {
        // handle error
    }
    CryptoKeyPlaintext_initKey(&cryptoKey, keyingMaterial, sizeof(keyingMaterial));
    AESECB_Operation_init(&operation);
    operation.key               = &cryptoKey;
    operation.input             = plaintext;
    operation.output            = ciphertext;
    operation.inputLength       = sizeof(plaintext);
    decryptionResult = AESECB_oneStepDecrypt(handle, &operation);
    if (decryptionResult != AESECB_STATUS_SUCCESS) {
        // handle error
    }
    // do other things while ECB operation completes in the background
}

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <ti/drivers/cryptoutils/cryptokey/CryptoKey.h>

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Data Structures
struct	AESECB_Operation_
	Struct containing the parameters required for encrypting/decrypting and a message. More...

struct	AESECB_Config_
	AESECB Global configuration. More...

struct	AESECB_Params_
	ECB Parameters. More...

Macros
#define	AESECB_STATUS_RESERVED (-32)

#define	AESECB_STATUS_SUCCESS (0)
	Successful status code. More...

#define	AESECB_STATUS_ERROR (-1)
	Generic error status code. More...

#define	AESECB_STATUS_RESOURCE_UNAVAILABLE (-2)
	An error status code returned if the hardware or software resource is currently unavailable. More...

#define	AESECB_STATUS_CANCELED (-3)
	The ongoing operation was canceled. More...

Typedefs
typedef struct AESECB_Config_ *	AESECB_Handle
	A handle that is returned from an AESECB_open() call. More...

typedef enum AESECB_ReturnBehavior_	AESECB_ReturnBehavior
	The way in which ECB function calls return after performing an encryption + authentication or decryption + verification operation. More...

typedef enum AESECB_Mode_	AESECB_Mode
	Enum for the direction of the ECB operation. More...

typedef struct AESECB_Operation_	AESECB_Operation
	Struct containing the parameters required for encrypting/decrypting and a message. More...

typedef enum AESECB_OperationType_	AESECB_OperationType
	Enum for the operation types supported by the driver. More...

typedef struct AESECB_Config_	AESECB_Config
	AESECB Global configuration. More...

typedef void(*	AESECB_CallbackFxn) (AESECB_Handle handle, int_fast16_t returnValue, AESECB_Operation *operation, AESECB_OperationType operationType)
	The definition of a callback function used by the AESECB driver when used in AESECB_RETURN_BEHAVIOR_CALLBACK. More...

typedef struct AESECB_Params_	AESECB_Params
	ECB Parameters. More...

Enumerations
enum	AESECB_ReturnBehavior_ { AESECB_RETURN_BEHAVIOR_CALLBACK = 1, AESECB_RETURN_BEHAVIOR_BLOCKING = 2, AESECB_RETURN_BEHAVIOR_POLLING = 4 }
	The way in which ECB function calls return after performing an encryption + authentication or decryption + verification operation. More...

enum	AESECB_Mode_ { AESECB_MODE_ENCRYPT = 1, AESECB_MODE_DECRYPT = 2 }
	Enum for the direction of the ECB operation. More...

enum	AESECB_OperationType_ { AESECB_OPERATION_TYPE_ENCRYPT = 1, AESECB_OPERATION_TYPE_DECRYPT = 2 }
	Enum for the operation types supported by the driver. More...

Functions
void	AESECB_init (void)
	This function initializes the ECB module. More...

void	AESECB_Params_init (AESECB_Params *params)
	Function to initialize the AESECB_Params struct to its defaults. More...

AESECB_Handle	AESECB_open (uint_least8_t index, AESECB_Params *params)
	This function opens a given ECB peripheral. More...

void	AESECB_close (AESECB_Handle handle)
	Function to close an ECB peripheral specified by the ECB handle. More...

void	AESECB_Operation_init (AESECB_Operation *operationStruct)
	Function to initialize an AESECB_Operation struct to its defaults. More...

int_fast16_t	AESECB_oneStepEncrypt (AESECB_Handle handle, AESECB_Operation *operation)
	Function to perform an AESECB encryption operation in one call. More...

int_fast16_t	AESECB_oneStepDecrypt (AESECB_Handle handle, AESECB_Operation *operation)
	Function to perform an AESECB decryption in one call. More...

int_fast16_t	AESECB_cancelOperation (AESECB_Handle handle)
	Cancels an ongoing AESECB operation. More...

Variables
const AESECB_Params	AESECB_defaultParams
	Default AESECB_Params structure. More...

Macro Definition Documentation

§ AESECB_STATUS_RESERVED

#define AESECB_STATUS_RESERVED (-32)

Common AESECB status code reservation offset. AESECB driver implementations should offset status codes with AESECB_STATUS_RESERVED growing negatively.

Example implementation specific status codes:

#define AESECBXYZ_STATUS_ERROR0    AESECB_STATUS_RESERVED - 0
#define AESECBXYZ_STATUS_ERROR1    AESECB_STATUS_RESERVED - 1
#define AESECBXYZ_STATUS_ERROR2    AESECB_STATUS_RESERVED - 2

§ AESECB_STATUS_SUCCESS

#define AESECB_STATUS_SUCCESS (0)

Successful status code.

Functions return AESECB_STATUS_SUCCESS if the function was executed successfully.

§ AESECB_STATUS_ERROR

#define AESECB_STATUS_ERROR (-1)

Generic error status code.

Functions return AESECB_STATUS_ERROR if the function was not executed successfully and no more pertinent error code could be returned.

§ AESECB_STATUS_RESOURCE_UNAVAILABLE

#define AESECB_STATUS_RESOURCE_UNAVAILABLE (-2)

An error status code returned if the hardware or software resource is currently unavailable.

AESECB driver implementations may have hardware or software limitations on how many clients can simultaneously perform operations. This status code is returned if the mutual exclusion mechanism signals that an operation cannot currently be performed.

§ AESECB_STATUS_CANCELED

#define AESECB_STATUS_CANCELED (-3)

The ongoing operation was canceled.

Typedef Documentation

§ AESECB_Handle

typedef struct AESECB_Config_* AESECB_Handle

A handle that is returned from an AESECB_open() call.

§ AESECB_ReturnBehavior

typedef enum AESECB_ReturnBehavior_ AESECB_ReturnBehavior

The way in which ECB function calls return after performing an encryption + authentication or decryption + verification operation.

Not all ECB operations exhibit the specified return behavor. Functions that do not require significant computation and cannot offload that computation to a background thread behave like regular functions. Which functions exhibit the specfied return behavior is not implementation dependent. Specifically, a software-backed implementation run on the same CPU as the application will emulate the return behavior while not actually offloading the computation to the background thread.

AESECB functions exhibiting the specified return behavior have restrictions on the context from which they may be called.

	Task	Hwi	Swi
AESECB_RETURN_BEHAVIOR_CALLBACK	X	X	X
AESECB_RETURN_BEHAVIOR_BLOCKING	X
AESECB_RETURN_BEHAVIOR_POLLING	X	X	X

§ AESECB_Mode

typedef enum AESECB_Mode_ AESECB_Mode

Enum for the direction of the ECB operation.

§ AESECB_Operation

typedef struct AESECB_Operation_ AESECB_Operation

Struct containing the parameters required for encrypting/decrypting and a message.

§ AESECB_OperationType

typedef enum AESECB_OperationType_ AESECB_OperationType

Enum for the operation types supported by the driver.

§ AESECB_Config

typedef struct AESECB_Config_ AESECB_Config

AESECB Global configuration.

The AESECB_Config structure contains a set of pointers used to characterize the AESECB driver implementation.

This structure needs to be defined before calling AESECB_init() and it must not be changed thereafter.

See also: AESECB_init()

§ AESECB_CallbackFxn

typedef void(* AESECB_CallbackFxn) (AESECB_Handle handle, int_fast16_t returnValue, AESECB_Operation *operation, AESECB_OperationType operationType)

The definition of a callback function used by the AESECB driver when used in AESECB_RETURN_BEHAVIOR_CALLBACK.

Parameters

handle	Handle of the client that started the ECB operation.
returnValue	The result of the CCM operation. May contain an error code. Informs the application of why the callback function was called.
operation	A pointer to an operation struct.
operationType	This parameter determines which operation the callback refers to.

§ AESECB_Params

typedef struct AESECB_Params_ AESECB_Params

ECB Parameters.

ECB Parameters are used to with the AESECB_open() call. Default values for these parameters are set using AESECB_Params_init().

See also: AESECB_Params_init()

Enumeration Type Documentation

§ AESECB_ReturnBehavior_

enum AESECB_ReturnBehavior_

The way in which ECB function calls return after performing an encryption + authentication or decryption + verification operation.

Not all ECB operations exhibit the specified return behavor. Functions that do not require significant computation and cannot offload that computation to a background thread behave like regular functions. Which functions exhibit the specfied return behavior is not implementation dependent. Specifically, a software-backed implementation run on the same CPU as the application will emulate the return behavior while not actually offloading the computation to the background thread.

AESECB functions exhibiting the specified return behavior have restrictions on the context from which they may be called.

	Task	Hwi	Swi
AESECB_RETURN_BEHAVIOR_CALLBACK	X	X	X
AESECB_RETURN_BEHAVIOR_BLOCKING	X
AESECB_RETURN_BEHAVIOR_POLLING	X	X	X

Enumerator
AESECB_RETURN_BEHAVIOR_CALLBACK	The function call will return immediately while the ECB operation goes on in the background. The registered callback function is called after the operation completes. The context the callback function is called (task, HWI, SWI) is implementation-dependent.
AESECB_RETURN_BEHAVIOR_BLOCKING	The function call will block while ECB operation goes on in the background. ECB operation results are available after the function returns.
AESECB_RETURN_BEHAVIOR_POLLING	The function call will continuously poll a flag while ECB operation goes on in the background. ECB operation results are available after the function returns.

§ AESECB_Mode_

enum AESECB_Mode_

Enum for the direction of the ECB operation.

Enumerator
AESECB_MODE_ENCRYPT
AESECB_MODE_DECRYPT

§ AESECB_OperationType_

enum AESECB_OperationType_

Enum for the operation types supported by the driver.

Enumerator
AESECB_OPERATION_TYPE_ENCRYPT
AESECB_OPERATION_TYPE_DECRYPT

Function Documentation

§ AESECB_init()

void AESECB_init ( void )

This function initializes the ECB module.

Precondition: The AESECB_config structure must exist and be persistent before this function can be called. This function must also be called before any other ECB driver APIs. This function call does not modify any peripheral registers.

§ AESECB_Params_init()

void AESECB_Params_init ( AESECB_Params * params )

Function to initialize the AESECB_Params struct to its defaults.

Parameters

params An pointer to AESECB_Params structure for initialization

Defaults values are: returnBehavior = AESECB_RETURN_BEHAVIOR_BLOCKING callbackFxn = NULL timeout = SemaphoreP_WAIT_FOREVER custom = NULL

§ AESECB_open()

AESECB_Handle AESECB_open	(	uint_least8_t	index,
		AESECB_Params *	params
	)

This function opens a given ECB peripheral.

Precondition: ECB controller has been initialized using AESECB_init()

Parameters

index	Logical peripheral number for the ECB indexed into the AESECB_config table
params	Pointer to an parameter block, if NULL it will use default values.

Returns: An AESECB_Handle on success or a NULL on an error or if it has been opened already.

See also: AESECB_init(); AESECB_close()

§ AESECB_close()

void AESECB_close ( AESECB_Handle handle )

Function to close an ECB peripheral specified by the ECB handle.

Precondition: AESECB_open() has to be called first.

Parameters

handle An ECB handle returned from AESECB_open()

See also: AESECB_open()

§ AESECB_Operation_init()

void AESECB_Operation_init ( AESECB_Operation * operationStruct )

Function to initialize an AESECB_Operation struct to its defaults.

Parameters

operationStruct An pointer to AESECB_Operation structure for initialization

Defaults values are all zeros.

§ AESECB_oneStepEncrypt()

int_fast16_t AESECB_oneStepEncrypt	(	AESECB_Handle	handle,
		AESECB_Operation *	operation
	)

Function to perform an AESECB encryption operation in one call.

Note: None of the buffers provided as arguments may be altered by the application during an ongoing operation. Doing so can yield corrupted ciphertext or incorrect authentication.

Precondition: AESECB_open() and AESECB_Operation_init() have to be called first.

Parameters

[in]	handle	An ECB handle returned from AESECB_open()
[in]	operation	A pointer to a struct containing the parameters required to perform the operation.

Returns: A status code

See also: AESECB_oneStepDecrypt()

§ AESECB_oneStepDecrypt()

int_fast16_t AESECB_oneStepDecrypt	(	AESECB_Handle	handle,
		AESECB_Operation *	operation
	)

Function to perform an AESECB decryption in one call.

Note: None of the buffers provided as arguments may be altered by the application during an ongoing operation. Doing so can yield corrupted plaintext or incorrectly failed verification.

Precondition: AESECB_open() and AESECB_Operation_init() have to be called first.

Parameters

[in]	handle	An ECB handle returned from AESECB_open()
[in]	operation	A pointer to a struct containing the parameters required to perform the operation.

Returns: A status code

See also: AESECB_oneStepEncrypt()

§ AESECB_cancelOperation()

int_fast16_t AESECB_cancelOperation ( AESECB_Handle handle )

Cancels an ongoing AESECB operation.

Asynchronously cancels an AESECB operation. Only available when using AESECB_RETURN_BEHAVIOR_CALLBACK or AESECB_RETURN_BEHAVIOR_BLOCKING. The operation will terminate as though an error occured. The return status code of the operation will be AESECB_STATUS_CANCELED.

Parameters

handle Handle of the operation to cancel

Returns: Returns a status code.

Variable Documentation

§ AESECB_defaultParams

const AESECB_Params AESECB_defaultParams

Default AESECB_Params structure.

See also: AESECB_Params_init()

Detailed Description

Overview

Usage

Before starting an ECB operation

Starting an ECB operation

After the ECB operation completes

AESECB Driver Configuration

AESECB Parameters

Examples

Single call ECB decryption in callback mode

Data Structures

Macros

Typedefs

Enumerations

Functions

Variables

Macro Definition Documentation

§ AESECB_STATUS_RESERVED

§ AESECB_STATUS_SUCCESS

§ AESECB_STATUS_ERROR

§ AESECB_STATUS_RESOURCE_UNAVAILABLE

§ AESECB_STATUS_CANCELED

Typedef Documentation

§ AESECB_Handle

§ AESECB_ReturnBehavior

§ AESECB_Mode

§ AESECB_Operation

§ AESECB_OperationType

§ AESECB_Config

§ AESECB_CallbackFxn

§ AESECB_Params

Enumeration Type Documentation

§ AESECB_ReturnBehavior_

§ AESECB_Mode_

§ AESECB_OperationType_

Function Documentation

§ AESECB_init()

§ AESECB_Params_init()

§ AESECB_open()

§ AESECB_close()

§ AESECB_Operation_init()

§ AESECB_oneStepEncrypt()

§ AESECB_oneStepDecrypt()

§ AESECB_cancelOperation()

Variable Documentation

§ AESECB_defaultParams