CAU3 AES driver

Overview

This section describes the programming interface of the CAU3 AES driver.

Macros
#define	CAU3_AES_BLOCK_SIZE   16
	AES block size in bytes.

Functions
status_t	CAU3_AES_SetKey (CAU3_Type *base, cau3_handle_t *handle, const uint8_t *key, size_t keySize)
	Load AES key into CAU3 key slot. More...
status_t	CAU3_AES_Encrypt (CAU3_Type *base, cau3_handle_t *handle, const uint8_t plaintext[16], uint8_t ciphertext[16])
	Encrypts AES on one 128-bit block. More...
status_t	CAU3_AES_Decrypt (CAU3_Type *base, cau3_handle_t *handle, const uint8_t ciphertext[16], uint8_t plaintext[16])
	Decrypts AES on one 128-bit block. More...
status_t	CAU3_AES_Cmac (CAU3_Type *base, cau3_handle_t *handle, const uint8_t *message, size_t size, uint8_t *mac)
	Perform an AES-128 cipher-based authentication code (CMAC) More...
status_t	CAU3_AES_KeyExpansion (CAU3_Type *base, cau3_key_slot_t keySlot, cau3_task_done_t taskDone)
	Perform an AES key expansion for specified key slot. More...

Function Documentation

status_t CAU3_AES_SetKey	(	CAU3_Type *	base,
		cau3_handle_t *	handle,
		const uint8_t *	key,
		size_t	keySize
	)

Load the key context into the private DMEM. This function also performs an AES key expansion. For CAU3 AES encryption/decryption/cmac, users only need to call one of CAU3_AES_SetKey and CAU3_LoadSpecialKeyContext.

CAU3_AES_SetKey

Parameters

base	CAU3 peripheral base address.
handle	Handle used for the request.
key	0-mod-4 aligned pointer to AES key.
keySize	AES key size in bytes. Shall equal 16 or 32.

Returns

status from set key operation

status_t CAU3_AES_Encrypt	(	CAU3_Type *	base,
		cau3_handle_t *	handle,
		const uint8_t	plaintext[16],
		uint8_t	ciphertext[16]
	)

Encrypts AES. The source plaintext and destination ciphertext can overlap in system memory.

Parameters

	base	CAU3 peripheral base address
	handle	Handle used for this request.
	plaintext	Input plain text to encrypt
[out]	ciphertext	Output cipher text

Returns

Status from encrypt operation

status_t CAU3_AES_Decrypt	(	CAU3_Type *	base,
		cau3_handle_t *	handle,
		const uint8_t	ciphertext[16],
		uint8_t	plaintext[16]
	)

Decrypts AES. The source ciphertext and destination plaintext can overlap in system memory.

Parameters

	base	CAU3 peripheral base address
	handle	Handle used for this request.
	ciphertext	Input plain text to encrypt
[out]	plaintext	Output cipher text

Returns

Status from decrypt operation

status_t CAU3_AES_Cmac	(	CAU3_Type *	base,
		cau3_handle_t *	handle,
		const uint8_t *	message,
		size_t	size,
		uint8_t *	mac
	)

Performs an AES-128 cipher-based authentication code (CMAC) on a message. RFC 4493.

Parameters

base	CAU3 peripheral base address
handle	Handle used for this request.
message	is source uint8_t array of data bytes, any alignment
size	Number of bytes in the message.
mac	is the output 16 bytes MAC, must be a 0-mod-4 aligned address

Returns

status check from task completion

status_t CAU3_AES_KeyExpansion	(	CAU3_Type *	base,
		cau3_key_slot_t	keySlot,
		cau3_task_done_t	taskDone
	)

Performs an AES key expansion (aka schedule) on the specified key slot. It uses the keySize information in the context to determine whether the key expansion applies to a 128- or 256-bit AES key. This function is primarily intended to be called after key blob has been unwrapped by CAU3_KeyBlobUnwrap to destination key slot, so that the unwrapped key can be used for AES encryption.

Parameters

base	CAU3 base address
keySlot	is the key context
taskDone	indicates completion signal

Returns

status check from task completion