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Eliminate extra block copy on encrypt

This commit is contained in:
Shawn Nock 2017-08-02 15:59:58 -04:00
parent f6da1e90b1
commit ec5d64c3a6
6 changed files with 14 additions and 16 deletions
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7
aes.c
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@ -21,21 +21,20 @@ void aes128_init(const uint8_t *key) {
return; return;
} }
void aes128_ecb(uint8_t *dest, uint8_t const *const in) { uint8_t *aes128_ecb(uint8_t const *const in) {
#ifdef HOST_BUILD #ifdef HOST_BUILD
AES_KEY key; AES_KEY key;
AES_set_encrypt_key(g_ecbdata.key, 128, &key); AES_set_encrypt_key(g_ecbdata.key, 128, &key);
AES_encrypt(in, g_ecbdata.out, &key); AES_encrypt(in, g_ecbdata.out, &key);
#else #else
memmove(g_ecbdata.in, in, 16); memcpy(g_ecbdata.in, in, 16);
NRF_ECB->TASKS_STARTECB = 1; NRF_ECB->TASKS_STARTECB = 1;
while (!NRF_ECB->EVENTS_ENDECB) { while (!NRF_ECB->EVENTS_ENDECB) {
; ;
} }
NRF_ECB->EVENTS_ENDECB = 0; NRF_ECB->EVENTS_ENDECB = 0;
#endif /* HOST_BUILD */ #endif /* HOST_BUILD */
memmove(dest, g_ecbdata.out, 16); return g_ecbdata.out;
return;
} }
#ifdef HOST_BUILD #ifdef HOST_BUILD

2
aes.h
View File

@ -11,5 +11,5 @@ typedef struct {
} ecbdata_t; } ecbdata_t;
void aes128_init(const uint8_t *); void aes128_init(const uint8_t *);
void aes128_ecb(uint8_t *, uint8_t const *const); uint8_t *aes128_ecb(uint8_t const *const);
void aes_dump_state(void); void aes_dump_state(void);

2
block.c
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@ -31,7 +31,7 @@ void block_print_bytes(char const *const label, void const *const v,
} }
#endif #endif
void block_xor(uint8_t *dest, uint8_t *const a, uint8_t *const b) { void block_xor(uint8_t *dest, uint8_t const *const a, uint8_t const *const b) {
for (uint_fast8_t i = 0; i < 4; i++) { for (uint_fast8_t i = 0; i < 4; i++) {
*((uint32_t *)dest + i) = *((uint32_t *)a + i) ^ *((uint32_t *)b + i); *((uint32_t *)dest + i) = *((uint32_t *)a + i) ^ *((uint32_t *)b + i);
} }

2
block.h
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@ -12,4 +12,4 @@ void block_print(char const *const, void const *const);
void block_print_bytes(char const *const, void const *const, uint32_t); void block_print_bytes(char const *const, void const *const, uint32_t);
void block_shiftl(uint8_t *, uint8_t *const, uint_fast8_t); void block_shiftl(uint8_t *, uint8_t *const, uint_fast8_t);
void block_shiftr(uint8_t *, uint8_t *const, uint_fast8_t); void block_shiftr(uint8_t *, uint8_t *const, uint_fast8_t);
void block_xor(uint8_t *, uint8_t *const, uint8_t *const); void block_xor(uint8_t *, uint8_t const *const, uint8_t const *const);

11
cmac.c
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@ -33,10 +33,9 @@ void cmac_aes128_init(const uint8_t *key) {
void cmac_aes128_expand_key(uint8_t const *const key, uint8_t *k1, void cmac_aes128_expand_key(uint8_t const *const key, uint8_t *k1,
uint8_t *k2) { uint8_t *k2) {
/* Generate two required subkeys according to NIST 800-38B */ /* Generate two required subkeys according to NIST 800-38B */
uint8_t l[16] = {0}, uint8_t Rb[16] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x87};
Rb[16] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x87};
aes128_ecb(l, zeros); uint8_t *l = aes128_ecb(zeros);
if ((l[0] >> 7) == 0) { if ((l[0] >> 7) == 0) {
block_shiftl(k1, l, 1); block_shiftl(k1, l, 1);
} else { } else {
@ -70,7 +69,7 @@ void cmac_aes128(uint8_t *dest, uint8_t *msg, size_t msg_len,
uint8_t alt_msg[num_blocks * 16], uint8_t alt_msg[num_blocks * 16],
*last_block = &alt_msg[(num_blocks - 1) * 16]; *last_block = &alt_msg[(num_blocks - 1) * 16];
memset(alt_msg, 0, num_blocks * 16); memset(alt_msg, 0, num_blocks * 16);
memmove(alt_msg, msg, msg_len); memcpy(alt_msg, msg, msg_len);
if (!last_block_complete) { if (!last_block_complete) {
/* Padding is single 1 bit, run out on 0s.. find the next byte, /* Padding is single 1 bit, run out on 0s.. find the next byte,
@ -81,12 +80,12 @@ void cmac_aes128(uint8_t *dest, uint8_t *msg, size_t msg_len,
block_xor(last_block, last_block, g_k1); block_xor(last_block, last_block, g_k1);
} }
uint8_t x[16] = {0}, y[16] = {0}; uint8_t *x = (uint8_t *)zeros, y[16] = {0};
for (uint32_t i = 0; i < num_blocks; i++) { for (uint32_t i = 0; i < num_blocks; i++) {
uint8_t *block = &alt_msg[i * 16]; uint8_t *block = &alt_msg[i * 16];
block_xor(y, x, block); block_xor(y, x, block);
aes128_ecb(x, y); x = aes128_ecb(y);
} }
cmac_truncate(dest, x, tag_len); cmac_truncate(dest, x, tag_len);
return; return;

6
ctr.c
View File

@ -20,15 +20,15 @@ void aes128_ctr_evolve_counter(void) {
} }
void aes128_ctr(uint8_t *dest, uint8_t *msg, uint32_t msg_len) { void aes128_ctr(uint8_t *dest, uint8_t *msg, uint32_t msg_len) {
uint8_t buffer[16]; uint8_t *buffer;
uint32_t num_blocks = msg_len / 16; uint32_t num_blocks = msg_len / 16;
for (uint32_t i = 0; i < num_blocks; i++) { for (uint32_t i = 0; i < num_blocks; i++) {
aes128_ecb(buffer, g_counter); buffer = aes128_ecb(g_counter);
aes128_ctr_evolve_counter(); aes128_ctr_evolve_counter();
block_xor(dest + (i * 16), msg + (i * 16), buffer); block_xor(dest + (i * 16), msg + (i * 16), buffer);
} }
if (msg_len % 16) { if (msg_len % 16) {
aes128_ecb(buffer, g_counter); buffer = aes128_ecb(g_counter);
for (uint8_t i = 0; i < msg_len % 16; i++) { for (uint8_t i = 0; i < msg_len % 16; i++) {
dest[num_blocks * 16 + i] = msg[num_blocks * 16 + i] ^ buffer[i]; dest[num_blocks * 16 + i] = msg[num_blocks * 16 + i] ^ buffer[i];
} }