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crypto/aes.c: This commit provides an improved AES cipher API in addition to the existing routines. The reasons for this new API are: 1) better performance, giving the possibility to avoid re-setting-up the key for each AES block when the same key is used multiple times. This is important for the current single user of AES, which is related to storage and FTL. And 2) suitable for simultaneous use of multiple AES keys, which will be required by the upcoming crypto framework. It retains compatibility with the previous API, so there is no need to change anything else right now.

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This commit is contained in:
Sebastien Lorquet 2018-12-18 10:19:26 -06:00 committed by Gregory Nutt
parent c897790e55
commit c912e53344
2 changed files with 151 additions and 6 deletions
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92
crypto/aes.c
View File

@ -105,7 +105,7 @@ static const uint8_t g_rcon[11] =
0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
};
static uint8_t g_expanded_key[176];
static aes_state_s g_aes_state;
/****************************************************************************
* Private Functions
@ -543,6 +543,88 @@ static void aes_decr(FAR uint8_t *state, FAR const uint8_t *expanded_key)
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: aes_setupkey
*
* Description:
* Configure the given AES context for operation with the selected key.
*
* Input Parameters:
* state an AES context that can be used for AES operations
* key a pointer to a 16-byte buffer holding the AES-128 key
* len length of the key, must be 16
*
* TODO: Support other key lengths of 24 (AES-192) and 32 (AES-256)
*
* Returned Value:
* 0 if OK
* -EINVAL if len is not 16
*
****************************************************************************/
int aes_setupkey(FAR struct aes_state_s *state, FAR const uint8_t *key, int len)
{
if (len != 16)
{
return -EINVAL;
}
expand_key(state->expanded_key, key);
return 0;
}
/****************************************************************************
* Name: aes_encipher
*
* Description:
* Encipher some 16-byte blocks (without any operation mode) using the
* previously defined key. The function can be called multiple times with
* the same state parameter.
*
* Returned Value:
* None
*
****************************************************************************/
void aes_encipher(FAR struct aes_state_s *state, FAR uint8_t *blocks,
int nblk)
{
int i;
uint32_t off = 0;
for (i = 0; i < nblk; i++)
{
aes_encr(blocks + off, state->expanded_key);
off += 16;
}
}
/****************************************************************************
* Name: aes_decipher
*
* Description:
* Decipher some 16-byte blocks (without any operation mode) using the
* previously defined key. The function can be called multiple times with
* the same state parameter.
*
* Returned Value:
* None
*
****************************************************************************/
void aes_decipher(FAR struct aes_state_s *state, FAR uint8_t *blocks,
int nblk)
{
int i;
uint32_t off = 0;
for (i = 0; i < nblk; i++)
{
aes_decr(blocks + off, state->expanded_key);
off += 16;
}
}
/****************************************************************************
* Name: aes_encrypt
*
@ -564,8 +646,8 @@ void aes_encrypt(FAR uint8_t *state, FAR const uint8_t *key)
{
/* Expand the key into 176 bytes */
expand_key(g_expanded_key, key);
aes_encr(state, g_expanded_key);
aes_setupkey(&g_aes_state->expanded_key, key, 16);
aes_encr(state, g_aes_state->expanded_key);
}
/****************************************************************************
@ -589,6 +671,6 @@ void aes_decrypt(FAR uint8_t *state, FAR const uint8_t *key)
{
/* Expand the key into 176 bytes */
expand_key(g_expanded_key, key);
aes_decr(state, g_expanded_key);
aes_setupkey(&g_aes_state->expanded_key, key, 16);
aes_decr(state, g_aes_state->expanded_key);
}

65
include/nuttx/crypto/aes.h
View File

@ -50,6 +50,15 @@
#define AES128_KEY_SIZE 16
/****************************************************************************
* Public Types
****************************************************************************/
struct aes_state_s
{
uint8_t expanded_key[176];
};
/****************************************************************************
* Public Data
****************************************************************************/
@ -61,7 +70,7 @@ extern "C"
/****************************************************************************
* Public Function Prototypes
/****************************************************************************
****************************************************************************/
/****************************************************************************
* Name: aes_encrypt
@ -101,6 +110,60 @@ void aes_encrypt(FAR uint8_t *state, FAR const uint8_t *key);
void aes_decrypt(FAR uint8_t *state, FAR const uint8_t *key);
/****************************************************************************
* Name: aes_setupkey
*
* Description:
* Configure the given AES context for operation with the selected key.
*
* Input Parameters:
* state an AES context that can be used for AES operations
* key a pointer to a 16-byte buffer holding the AES-128 key
* len length of the key, must be 16
*
* TODO: Support other key lengths of 24 (AES-192) and 32 (AES-256)
*
* Returned Value:
* 0 if OK
* -EINVAL if len is not 16
*
****************************************************************************/
int aes_setupkey(FAR struct aes_state_s *state, FAR const uint8_t *key,
int len);
/****************************************************************************
* Name: aes_encipher
*
* Description:
* Encipher some 16-byte blocks (without any operation mode) using the
* previously defined key. The function can be called multiple times with
* the same state parameter.
*
* Returned Value:
* None
*
****************************************************************************/
void aes_encipher(FAR struct aes_state_s *state, FAR uint8_t *blocks,
int nblk);
/****************************************************************************
* Name: aes_decipher
*
* Description:
* Decipher some 16-byte blocks (without any operation mode) using the
* previously defined key. The function can be called multiple times with
* the same state parameter.
*
* Returned Value:
* None
*
****************************************************************************/
void aes_decipher(FAR struct aes_state_s *state, FAR uint8_t *blocks,
int nblk);
#ifdef __cplusplus
}
#endif /* __cplusplus */