tc_aes.h File Reference

– Interface to an AES-128 implementation. More...

#include <stdint.h>

Go to the source code of this file.

Data Structures
struct	tc_aes_key_sched_struct

Macros
#define	Nb   (4) /* number of columns (32-bit words) comprising the state */
#define	Nk   (4) /* number of 32-bit words comprising the key */
#define	Nr   (10) /* number of rounds */
#define	TC_AES_BLOCK_SIZE   (Nb*Nk)
#define	TC_AES_KEY_SIZE   (Nb*Nk)

Typedefs
typedef struct tc_aes_key_sched_struct *	TCAesKeySched_t

Functions
int	tc_aes128_set_encrypt_key (TCAesKeySched_t s, const uint8_t *k)
	Set AES-128 encryption key Uses key k to initialize s. More...
int	tc_aes_encrypt (uint8_t *out, const uint8_t *in, const TCAesKeySched_t s)
	AES-128 Encryption procedure Encrypts contents of in buffer into out buffer under key; schedule s. More...
int	tc_aes128_set_decrypt_key (TCAesKeySched_t s, const uint8_t *k)
	Set the AES-128 decryption key Uses key k to initialize s. More...
int	tc_aes_decrypt (uint8_t *out, const uint8_t *in, const TCAesKeySched_t s)
	AES-128 Encryption procedure Decrypts in buffer into out buffer under key schedule s. More...

Detailed Description

– Interface to an AES-128 implementation.

Overview: AES-128 is a NIST approved block cipher specified in FIPS 197. Block ciphers are deterministic algorithms that perform a transformation specified by a symmetric key in fixed- length data sets, also called blocks.

Security: AES-128 provides approximately 128 bits of security.

Usage: 1) call tc_aes128_set_encrypt/decrypt_key to set the key.

        2) call tc_aes_encrypt/decrypt to process the data.

Macro Definition Documentation

Nb

#define Nb   (4) /* number of columns (32-bit words) comprising the state */

Nk

#define Nk   (4) /* number of 32-bit words comprising the key */

Nr

#define Nr   (10) /* number of rounds */

TC_AES_BLOCK_SIZE

#define TC_AES_BLOCK_SIZE   (Nb*Nk)

TC_AES_KEY_SIZE

#define TC_AES_KEY_SIZE   (Nb*Nk)

Typedef Documentation

TCAesKeySched_t

typedef struct tc_aes_key_sched_struct * TCAesKeySched_t

Function Documentation

tc_aes128_set_decrypt_key()

int tc_aes128_set_decrypt_key	(	TCAesKeySched_t	s,
		const uint8_t *	k
	)

Set the AES-128 decryption key Uses key k to initialize s.

Returns

returns TC_CRYPTO_SUCCESS (1) returns TC_CRYPTO_FAIL (0) if: s == NULL or k == NULL

Note

This is the implementation of the straightforward inverse cipher using the cipher documented in FIPS-197 figure 12, not the equivalent inverse cipher presented in Figure 15

Warning

This routine skips the additional steps required for keys larger than 128, and must not be used for AES-192 or AES-256 key schedule – see FIPS 197 for details

Parameters

s	IN/OUT – initialized struct tc_aes_key_sched_struct
k	IN – points to the AES key

tc_aes128_set_encrypt_key()

int tc_aes128_set_encrypt_key	(	TCAesKeySched_t	s,
		const uint8_t *	k
	)

Set AES-128 encryption key Uses key k to initialize s.

Returns

returns TC_CRYPTO_SUCCESS (1) returns TC_CRYPTO_FAIL (0) if: s == NULL or k == NULL

Note

This implementation skips the additional steps required for keys larger than 128 bits, and must not be used for AES-192 or AES-256 key schedule – see FIPS 197 for details

Parameters

s	IN/OUT – initialized struct tc_aes_key_sched_struct
k	IN – points to the AES key

tc_aes_decrypt()

int tc_aes_decrypt	(	uint8_t *	out,
		const uint8_t *	in,
		const TCAesKeySched_t	s
	)

AES-128 Encryption procedure Decrypts in buffer into out buffer under key schedule s.

Returns

returns TC_CRYPTO_SUCCESS (1) returns TC_CRYPTO_FAIL (0) if: out is NULL or in is NULL or s is NULL

Note

Assumes s was initialized by aes_set_encrypt_key out and in point to 16 byte buffers

Parameters

out	IN/OUT – buffer to receive ciphertext block
in	IN – a plaintext block to encrypt
s	IN – initialized AES key schedule

tc_aes_encrypt()

int tc_aes_encrypt	(	uint8_t *	out,
		const uint8_t *	in,
		const TCAesKeySched_t	s
	)

AES-128 Encryption procedure Encrypts contents of in buffer into out buffer under key; schedule s.

Note

Assumes s was initialized by aes_set_encrypt_key; out and in point to 16 byte buffers

Returns

returns TC_CRYPTO_SUCCESS (1) returns TC_CRYPTO_FAIL (0) if: out == NULL or in == NULL or s == NULL

Parameters

out	IN/OUT – buffer to receive ciphertext block
in	IN – a plaintext block to encrypt
s	IN – initialized AES key schedule