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require that we collect at least 20 bytes (hash size) of good randomness

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before allowing pseudorandom operation.
This commit is contained in:
Michael Graff
2000-06-12 18:19:43 +00:00
parent c0975ccf5c
commit 8422b3823f
1 changed files with 34 additions and 1 deletions
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35
lib/isc/unix/entropy.c
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@@ -77,9 +77,10 @@ typedef struct {
struct isc_entropy {
isc_uint32_t magic;
isc_mem_t *mctx;
isc_mutex_t lock;
unsigned int refcnt;
isc_mem_t *mctx;
isc_uint32_t initialized;
isc_entropypool_t pool;
ISC_LIST(isc_entropysource_t) sources;
};
@@ -367,6 +368,13 @@ fillpool(isc_entropy_t *ent, unsigned int needed, isc_boolean_t blocking) {
*/
needed = ISC_MIN(needed, RND_POOLBITS - ent->pool.entropy);
/*
* But wait! If we're not yet initialized, we need at least 20
* bytes of randomness.
*/
if (ent->initialized < 20)
needed = ISC_MIN(needed, 20 - ent->initialized);
/*
* Poll each file source to see if we can read anything useful from
* it. XXXMLG When where are multiple sources, we should keep a
@@ -411,6 +419,15 @@ fillpool(isc_entropy_t *ent, unsigned int needed, isc_boolean_t blocking) {
* Adjust counts.
*/
subtract_pseudo(ent, added);
/*
* Mark as initialized if we've added enough data.
*/
if (ent->initialized < 20) {
ent->initialized += added;
if (ent->initialized >= 20)
ent->initialized = ISC_TRUE;
}
}
static int
@@ -529,6 +546,13 @@ isc_entropy_getdata(isc_entropy_t *ent, void *data, unsigned int length,
* since the last refresh, try to refresh here.
*/
fillpool(ent, 0, ISC_FALSE);
/*
* If we've not initialized with enough good random
* data, fail.
*/
if (ent->initialized < 20)
goto zeroize;
}
isc_sha1_init(&hash);
@@ -621,6 +645,7 @@ isc_entropy_create(isc_mem_t *mctx, isc_entropy_t **entp) {
ent->mctx = NULL;
isc_mem_attach(mctx, &ent->mctx);
ent->refcnt = 1;
ent->initialized = 0;
ent->magic = ENTROPY_MAGIC;
isc_entropypool_init(&ent->pool);
@@ -825,6 +850,14 @@ isc_entropy_addsample(isc_entropysource_t *source, isc_uint32_t sample,
{
isc_entropy_t *ent;
/*
* XXXMLG Make warnings go away for the beta4 release. This
* will be fixed by implementing the function in the next
* release.
*/
UNUSED(sample);
UNUSED(extra);
REQUIRE(VALID_SOURCE(source));
ent = source->ent;