Overview

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

Macros
#define	LTC_AES_BLOCK_SIZE 16U
	AES block size in bytes.

#define	LTC_AES_IV_SIZE 16
	AES Input Vector size in bytes.

#define	LTC_AES_DecryptCtr(base, input, output, size, counter, key, keySize, counterlast, szLeft) LTC_AES_CryptCtr(base, input, output, size, counter, key, keySize, counterlast, szLeft)
	AES CTR decrypt is mapped to the AES CTR generic operation.

#define	LTC_AES_EncryptCtr(base, input, output, size, counter, key, keySize, counterlast, szLeft) LTC_AES_CryptCtr(base, input, output, size, counter, key, keySize, counterlast, szLeft)
	AES CTR encrypt is mapped to the AES CTR generic operation.

Enumerations
enum	ltc_aes_key_t { kLTC_EncryptKey = 0U, kLTC_DecryptKey = 1U }
	Type of AES key for ECB and CBC decrypt operations. More...

Functions
status_t	LTC_AES_GenerateDecryptKey (LTC_Type base, const uint8_t encryptKey, uint8_t *decryptKey, uint32_t keySize)
	Transforms an AES encrypt key (forward AES) into the decrypt key (inverse AES). More...

status_t	LTC_AES_EncryptEcb (LTC_Type base, const uint8_t plaintext, uint8_t ciphertext, uint32_t size, const uint8_t key, uint32_t keySize)
	Encrypts AES using the ECB block mode. More...

status_t	LTC_AES_DecryptEcb (LTC_Type base, const uint8_t ciphertext, uint8_t plaintext, uint32_t size, const uint8_t key, uint32_t keySize, ltc_aes_key_t keyType)
	Decrypts AES using ECB block mode. More...

status_t	LTC_AES_EncryptCbc (LTC_Type base, const uint8_t plaintext, uint8_t ciphertext, uint32_t size, const uint8_t iv[LTC_AES_IV_SIZE], const uint8_t key, uint32_t keySize)
	Encrypts AES using CBC block mode. More...

status_t	LTC_AES_DecryptCbc (LTC_Type base, const uint8_t ciphertext, uint8_t plaintext, uint32_t size, const uint8_t iv[LTC_AES_IV_SIZE], const uint8_t key, uint32_t keySize, ltc_aes_key_t keyType)
	Decrypts AES using CBC block mode. More...

status_t	LTC_AES_CryptCtr (LTC_Type base, const uint8_t input, uint8_t output, uint32_t size, uint8_t counter[LTC_AES_BLOCK_SIZE], const uint8_t key, uint32_t keySize, uint8_t counterlast[LTC_AES_BLOCK_SIZE], uint32_t *szLeft)
	Encrypts or decrypts AES using CTR block mode. More...

status_t	LTC_AES_EncryptTagCcm (LTC_Type base, const uint8_t plaintext, uint8_t ciphertext, uint32_t size, const uint8_t iv, uint32_t ivSize, const uint8_t aad, uint32_t aadSize, const uint8_t key, uint32_t keySize, uint8_t *tag, uint32_t tagSize)
	Encrypts AES and tags using CCM block mode. More...

status_t	LTC_AES_DecryptTagCcm (LTC_Type base, const uint8_t ciphertext, uint8_t plaintext, uint32_t size, const uint8_t iv, uint32_t ivSize, const uint8_t aad, uint32_t aadSize, const uint8_t key, uint32_t keySize, const uint8_t *tag, uint32_t tagSize)
	Decrypts AES and authenticates using CCM block mode. More...

Enumeration Type Documentation

enum ltc_aes_key_t

Enumerator
kLTC_EncryptKey	Input key is an encrypt key.
kLTC_DecryptKey	Input key is a decrypt key.

Function Documentation

status_t LTC_AES_GenerateDecryptKey	(	LTC_Type *	base,
		const uint8_t *	encryptKey,
		uint8_t *	decryptKey,
		uint32_t	keySize
	)

Transforms the AES encrypt key (forward AES) into the decrypt key (inverse AES). The key derived by this function can be used as a direct load decrypt key for AES ECB and CBC decryption operations (keyType argument).

Parameters

	base	LTC peripheral base address
	encryptKey	Input key for decrypt key transformation
[out]	decryptKey	Output key, the decrypt form of the AES key.
	keySize	Size of the input key and output key in bytes. Must be 16, 24, or 32.

Returns: Status from key generation operation

status_t LTC_AES_EncryptEcb	(	LTC_Type *	base,
		const uint8_t *	plaintext,
		uint8_t *	ciphertext,
		uint32_t	size,
		const uint8_t *	key,
		uint32_t	keySize
	)

Encrypts AES using the ECB block mode.

Parameters

	base	LTC peripheral base address
	plaintext	Input plain text to encrypt
[out]	ciphertext	Output cipher text
	size	Size of input and output data in bytes. Must be multiple of 16 bytes.
	key	Input key to use for encryption
	keySize	Size of the input key, in bytes. Must be 16, 24, or 32.

Returns: Status from encrypt operation

status_t LTC_AES_DecryptEcb	(	LTC_Type *	base,
		const uint8_t *	ciphertext,
		uint8_t *	plaintext,
		uint32_t	size,
		const uint8_t *	key,
		uint32_t	keySize,
		ltc_aes_key_t	keyType
	)

Decrypts AES using ECB block mode.

Parameters

	base	LTC peripheral base address
	ciphertext	Input cipher text to decrypt
[out]	plaintext	Output plain text
	size	Size of input and output data in bytes. Must be multiple of 16 bytes.
	key	Input key.
	keySize	Size of the input key, in bytes. Must be 16, 24, or 32.
	keyType	Input type of the key (allows to directly load decrypt key for AES ECB decrypt operation.)

Returns: Status from decrypt operation

status_t LTC_AES_EncryptCbc	(	LTC_Type *	base,
		const uint8_t *	plaintext,
		uint8_t *	ciphertext,
		uint32_t	size,
		const uint8_t	iv[LTC_AES_IV_SIZE],
		const uint8_t *	key,
		uint32_t	keySize
	)

Parameters

	base	LTC peripheral base address
	plaintext	Input plain text to encrypt
[out]	ciphertext	Output cipher text
	size	Size of input and output data in bytes. Must be multiple of 16 bytes.
	iv	Input initial vector to combine with the first input block.
	key	Input key to use for encryption
	keySize	Size of the input key, in bytes. Must be 16, 24, or 32.

Returns: Status from encrypt operation

status_t LTC_AES_DecryptCbc	(	LTC_Type *	base,
		const uint8_t *	ciphertext,
		uint8_t *	plaintext,
		uint32_t	size,
		const uint8_t	iv[LTC_AES_IV_SIZE],
		const uint8_t *	key,
		uint32_t	keySize,
		ltc_aes_key_t	keyType
	)

Parameters

	base	LTC peripheral base address
	ciphertext	Input cipher text to decrypt
[out]	plaintext	Output plain text
	size	Size of input and output data in bytes. Must be multiple of 16 bytes.
	iv	Input initial vector to combine with the first input block.
	key	Input key to use for decryption
	keySize	Size of the input key, in bytes. Must be 16, 24, or 32.
	keyType	Input type of the key (allows to directly load decrypt key for AES CBC decrypt operation.)

Returns: Status from decrypt operation

status_t LTC_AES_CryptCtr	(	LTC_Type *	base,
		const uint8_t *	input,
		uint8_t *	output,
		uint32_t	size,
		uint8_t	counter[LTC_AES_BLOCK_SIZE],
		const uint8_t *	key,
		uint32_t	keySize,
		uint8_t	counterlast[LTC_AES_BLOCK_SIZE],
		uint32_t *	szLeft
	)

Encrypts or decrypts AES using CTR block mode. AES CTR mode uses only forward AES cipher and same algorithm for encryption and decryption. The only difference between encryption and decryption is that, for encryption, the input argument is plain text and the output argument is cipher text. For decryption, the input argument is cipher text and the output argument is plain text.

Parameters

	base	LTC peripheral base address
	input	Input data for CTR block mode
[out]	output	Output data for CTR block mode
	size	Size of input and output data in bytes
[in,out]	counter	Input counter (updates on return)
	key	Input key to use for forward AES cipher
	keySize	Size of the input key, in bytes. Must be 16, 24, or 32.
[out]	counterlast	Output cipher of last counter, for chained CTR calls. NULL can be passed if chained calls are not used.
[out]	szLeft	Output number of bytes in left unused in counterlast block. NULL can be passed if chained calls are not used.

Returns: Status from encrypt operation

status_t LTC_AES_EncryptTagCcm	(	LTC_Type *	base,
		const uint8_t *	plaintext,
		uint8_t *	ciphertext,
		uint32_t	size,
		const uint8_t *	iv,
		uint32_t	ivSize,
		const uint8_t *	aad,
		uint32_t	aadSize,
		const uint8_t *	key,
		uint32_t	keySize,
		uint8_t *	tag,
		uint32_t	tagSize
	)

Encrypts AES and optionally tags using CCM block mode.

Parameters

	base	LTC peripheral base address
	plaintext	Input plain text to encrypt
[out]	ciphertext	Output cipher text.
	size	Size of input and output data in bytes. Zero means authentication only.
	iv	Nonce
	ivSize	Length of the Nonce in bytes. Must be 7, 8, 9, 10, 11, 12, or 13.
	aad	Input additional authentication data. Can be NULL if aadSize is zero.
	aadSize	Input size in bytes of AAD. Zero means data mode only (authentication skipped).
	key	Input key to use for encryption
	keySize	Size of the input key, in bytes. Must be 16, 24, or 32.
[out]	tag	Generated output tag. Set to NULL to skip tag processing.
	tagSize	Input size of the tag to generate, in bytes. Must be 4, 6, 8, 10, 12, 14, or 16.

Returns: Status from encrypt operation

status_t LTC_AES_DecryptTagCcm	(	LTC_Type *	base,
		const uint8_t *	ciphertext,
		uint8_t *	plaintext,
		uint32_t	size,
		const uint8_t *	iv,
		uint32_t	ivSize,
		const uint8_t *	aad,
		uint32_t	aadSize,
		const uint8_t *	key,
		uint32_t	keySize,
		const uint8_t *	tag,
		uint32_t	tagSize
	)

Decrypts AES and optionally authenticates using CCM block mode.

Parameters

	base	LTC peripheral base address
	ciphertext	Input cipher text to decrypt
[out]	plaintext	Output plain text.
	size	Size of input and output data in bytes. Zero means authentication only.
	iv	Nonce
	ivSize	Length of the Nonce in bytes. Must be 7, 8, 9, 10, 11, 12, or 13.
	aad	Input additional authentication data. Can be NULL if aadSize is zero.
	aadSize	Input size in bytes of AAD. Zero means data mode only (authentication skipped).
	key	Input key to use for decryption
	keySize	Size of the input key, in bytes. Must be 16, 24, or 32.
	tag	Received tag. Set to NULL to skip tag processing.
	tagSize	Input size of the received tag to compare with the computed tag, in bytes. Must be 4, 6, 8, 10, 12, 14, or 16.

Returns: Status from decrypt operation

Overview

Macros

Enumerations

Functions

Enumeration Type Documentation

Function Documentation