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Merge pull request #5577 from tmael/vx_entropy

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Improves entropy with VxWorks
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JacobBarthelmeh 2022-09-09 15:51:24 -06:00 committed by GitHub
commit 460b6f1ecc
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1 changed files with 31 additions and 1 deletions
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32
wolfcrypt/src/random.c
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@ -2240,9 +2240,12 @@ int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
}
#else
#include <randomNumGen.h>
#include <tickLib.h>
int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz) {
STATUS status;
STATUS status = ERROR;
RANDOM_NUM_GEN_STATUS r_status = RANDOM_NUM_GEN_ERROR;
_Vx_ticks_t seed = 0;
#ifdef VXWORKS_SIM
/* cannot generate true entropy with VxWorks simulator */
@ -2254,7 +2257,34 @@ int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
}
#endif
/*
wolfSSL can request 52 Bytes of random bytes. We need to add
buffer to the entropy pool to ensure we can get more than 32 Bytes.
Because VxWorks has entropy limits (ENTROPY_MIN and ENTROPY_MAX)
defined as 256 and 1024 bits, see randomSWNumGenLib.c.
randStatus() can return the following status:
RANDOM_NUM_GEN_NO_ENTROPY when entropy is 0
RANDOM_NUM_GEN_ERROR, entropy is not initialized
RANDOM_NUM_GEN_NOT_ENOUGH_ENTROPY if entropy < 32 Bytes
RANDOM_NUM_GEN_ENOUGH_ENTROPY if entropy is between 32 and 128 Bytes
RANDOM_NUM_GEN_MAX_ENTROPY if entropy is greater than 128 Bytes
*/
do {
seed = tickGet();
status = randAdd(&seed, sizeof(_Vx_ticks_t), 2);
if (status == OK)
r_status = randStatus();
} while (r_status != RANDOM_NUM_GEN_MAX_ENTROPY &&
r_status != RANDOM_NUM_GEN_ERROR && status == OK);
if (r_status == RANDOM_NUM_GEN_ERROR)
return RNG_FAILURE_E;
status = randBytes (output, sz);
if (status == ERROR) {
return RNG_FAILURE_E;
}