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Nuvoton: TRNG_Get support 32 bytes unalignment #5454

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Merged
merged 5 commits into from
Nov 22, 2017
Merged

Nuvoton: TRNG_Get support 32 bytes unalignment #5454

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4118afa
[M487/NUC472] TRN_Get support 32 bytes unalignment
cyliangtw Nov 8, 2017
76c2c19
[M487/NUC472] Unified code-path for remaining bytes of TRNG_Get
cyliangtw Nov 8, 2017
e252b10
[M487/NUC472] zeroize random data on the stack memory
cyliangtw Nov 9, 2017
2ee058b
[M487/NUC472] Refine for correctness control
cyliangtw Nov 10, 2017
d8a9e35
[M487/NUC472] Refine trng_get_bytes for consistency and readability
cyliangtw Nov 13, 2017
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35 changes: 22 additions & 13 deletions targets/TARGET_NUVOTON/TARGET_M480/trng_api.c
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Original file line number Diff line number Diff line change
Expand Up @@ -25,9 +25,17 @@
/*
* Get Random number generator.
*/

#define PRNG_KEY_SIZE (0x20UL)

static volatile int g_PRNG_done;
volatile int g_AES_done;

/* Implementation that should never be optimized out by the compiler */
static void trng_zeroize( void *v, size_t n ) {
volatile unsigned char *p = (unsigned char*)v; while( n-- ) *p++ = 0;
}

void CRYPTO_IRQHandler()
{
if (PRNG_GET_INT_FLAG()) {
Expand Down Expand Up @@ -77,21 +85,22 @@ void trng_free(trng_t *obj)
int trng_get_bytes(trng_t *obj, uint8_t *output, size_t length, size_t *output_length)
{
(void)obj;

*output_length = 0;
if (length < 32) {
unsigned char tmpBuff[32];
unsigned char tmpBuff[PRNG_KEY_SIZE];
size_t cur_length = 0;

while (length >= sizeof(tmpBuff)) {
trng_get(output);
output += sizeof(tmpBuff);
cur_length += sizeof(tmpBuff);
length -= sizeof(tmpBuff);
}
if (length > 0) {
trng_get(tmpBuff);
memcpy(output, &tmpBuff, length);
*output_length = length;
} else {
for (unsigned i = 0; i < (length/32); i++) {
trng_get(output);
*output_length += 32;
output += 32;
}
memcpy(output, tmpBuff, length);
cur_length += length;
trng_zeroize(tmpBuff, sizeof(tmpBuff));
}

*output_length = cur_length;
return 0;
}

Expand Down
35 changes: 22 additions & 13 deletions targets/TARGET_NUVOTON/TARGET_NUC472/trng_api.c
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Original file line number Diff line number Diff line change
Expand Up @@ -30,9 +30,17 @@
/*
* Get Random number generator.
*/

#define PRNG_KEY_SIZE (0x20UL)

static volatile int g_PRNG_done;
volatile int g_AES_done;

/* Implementation that should never be optimized out by the compiler */
static void trng_zeroize( void *v, size_t n ) {
volatile unsigned char *p = (unsigned char*)v; while( n-- ) *p++ = 0;
}

void CRYPTO_IRQHandler()
{
if (PRNG_GET_INT_FLAG()) {
Expand Down Expand Up @@ -82,21 +90,22 @@ void trng_free(trng_t *obj)
int trng_get_bytes(trng_t *obj, uint8_t *output, size_t length, size_t *output_length)
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trng_get_bytes looks pretty similar between TARGET_NUC472 and TARGET_M480. Would it be prudent to move it to a location shared by both TARGET_NUC472 and TARGET_M480?

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@Patater We will consider to be shared as while one more platform utilize the same HW IP.

{
(void)obj;

*output_length = 0;
if (length < 32) {
unsigned char tmpBuff[32];
unsigned char tmpBuff[PRNG_KEY_SIZE];
size_t cur_length = 0;

while (length >= sizeof(tmpBuff)) {
trng_get(output);
output += sizeof(tmpBuff);
cur_length += sizeof(tmpBuff);
length -= sizeof(tmpBuff);
}
if (length > 0) {
trng_get(tmpBuff);
memcpy(output, &tmpBuff, length);
*output_length = length;
} else {
for (int i = 0; i < (length/32); i++) {
trng_get(output);
*output_length += 32;
output += 32;
}
memcpy(output, tmpBuff, length);
cur_length += length;
trng_zeroize(tmpBuff, sizeof(tmpBuff));
}

*output_length = cur_length;
return 0;
}

Expand Down