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wolfEntropy Adaptive Proportion Fix 2025

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kaleb-himes
2025-06-24 10:22:49 -06:00
parent 32c5acca22
commit e04a7b5782
1 changed files with 38 additions and 15 deletions
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53
wolfcrypt/src/random.c
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@@ -1083,6 +1083,16 @@ static word64 Entropy_GetSample(void)
word64 now;
word64 ret;
#ifdef HAVE_FIPS
/* First sample must be disregard when in FIPS. */
if (entropy_last_time == 0) {
/* Get sample which triggers CAST in FIPS mode. */
Entropy_MemUse();
/* Start entropy time after CASTs. */
entropy_last_time = Entropy_TimeHiRes();
}
#endif
/* Use memory such that it will take an unpredictable amount of time. */
Entropy_MemUse();
@@ -1184,6 +1194,7 @@ static int Entropy_HealthTest_Repetition(byte noise)
if (!rep_have_prev) {
rep_prev_noise = noise;
rep_have_prev = 1;
rep_cnt = 1;
}
/* Check whether this sample matches last. */
else if (noise == rep_prev_noise) {
@@ -1217,7 +1228,7 @@ static int Entropy_HealthTest_Repetition(byte noise)
/* SP800-90b 4.4.2 - Adaptive Proportion Test
* Note 10
* C = 1 + CRITBINOM(W, power(2,( -H)),1-alpha)
* alpa = 2^-30 = POWER(2,-30), H = 1, W = 512
* alpha = 2^-30 = POWER(2,-30), H = 1, W = 512
* C = 1 + CRITBINOM(512, 0.5, 1-POWER(2,-30)) = 1 + 324 = 325
*/
#define PROP_CUTOFF 325
@@ -1267,8 +1278,9 @@ static int Entropy_HealthTest_Proportion(byte noise)
{
int ret = 0;
/* Need at least 512-1 samples to test with. */
if (prop_total < PROP_WINDOW_SIZE - 1) {
/* Need minimum samples in queue to test with - keep adding while we have
* less. */
if (prop_total < PROP_CUTOFF - 1) {
/* Store sample at last position in circular queue. */
prop_samples[prop_last++] = noise;
/* Update count of seen value based on new sample. */
@@ -1277,27 +1289,36 @@ static int Entropy_HealthTest_Proportion(byte noise)
prop_total++;
}
else {
/* Get first value in queue - value to test. */
byte val = (byte)prop_samples[prop_first];
/* Store new sample in queue. */
/* We have at least a minimum set of samples in queue. */
/* Store new sample at end of queue. */
prop_samples[prop_last] = noise;
/* Update first index now that we have removed in from the queue. */
prop_first = (prop_first + 1) % PROP_WINDOW_SIZE;
/* Update last index now that we have added new sample to queue. */
prop_last = (prop_last + 1) % PROP_WINDOW_SIZE;
/* Removed sample from queue - remove count. */
prop_cnt[val]--;
/* Added sample to queue - add count. */
prop_cnt[noise]++;
/* Check whether removed value has too many repetitions in queue. */
if (prop_cnt[val] >= PROP_CUTOFF) {
/* Update count of store values. */
prop_total++;
/* Check whether first value has too many repetitions in queue. */
if (prop_cnt[noise] >= PROP_CUTOFF) {
#ifdef WOLFSSL_DEBUG_ENTROPY_MEMUSE
fprintf(stderr, "PROPORTION FAILED: %d %d\n", val, prop_cnt[val]);
fprintf(stderr, "PROPORTION FAILED: %d %d\n", val, prop_cnt[noise]);
#endif
Entropy_HealthTest_Proportion_Reset();
/* Error code returned. */
ret = ENTROPY_APT_E;
}
else if (prop_total == PROP_WINDOW_SIZE) {
/* Return to 511 samples in queue. */
/* Get first value in queue - value to test. */
byte val = (byte) prop_samples[prop_first];
/* Update first index to remove first sample from the queue. */
prop_first = (prop_first + 1) % PROP_WINDOW_SIZE;
/* Remove first sample from queue - remove count. */
prop_cnt[val]--;
/* Update count of store values. */
prop_total--;
}
}
return ret;
@@ -1330,6 +1351,10 @@ static int Entropy_HealthTest_Startup(void)
#ifdef WOLFSSL_DEBUG_ENTROPY_MEMUSE
fprintf(stderr, "STARTUP HEALTH TEST\n");
#endif
/* Reset cached values before testing. */
Entropy_HealthTest_Reset();
/* Fill initial sample buffer with noise. */
Entropy_GetNoise(initial, ENTROPY_INITIAL_COUNT);
/* Health check initial noise. */
@@ -1496,8 +1521,6 @@ int wc_Entropy_OnDemandTest(void)
}
if (ret == 0) {
/* Reset health test state for startup test. */
Entropy_HealthTest_Reset();
/* Perform startup tests. */
ret = Entropy_HealthTest_Startup();
}