int
yarrow256_update(struct yarrow256_ctx *ctx,
unsigned source_index, unsigned entropy,
size_t length, const uint8_t *data)
{
enum yarrow_pool_id current;
struct yarrow_source *source;
assert(source_index < ctx->nsources);
if (!length)
/* Nothing happens */
return 0;
source = &ctx->sources[source_index];
if (!ctx->seeded)
/* While seeding, use the slow pool */
current = YARROW_SLOW;
else
{
current = source->next;
source->next = !source->next;
}
sha256_update(&ctx->pools[current], length, data);
/* NOTE: We should be careful to avoid overflows in the estimates. */
if (source->estimate[current] < YARROW_MAX_ENTROPY)
{
if (entropy > YARROW_MAX_ENTROPY)
entropy = YARROW_MAX_ENTROPY;
if ( (length < (YARROW_MAX_ENTROPY / YARROW_MULTIPLIER))
&& (entropy > YARROW_MULTIPLIER * length) )
entropy = YARROW_MULTIPLIER * length;
entropy += source->estimate[current];
if (entropy > YARROW_MAX_ENTROPY)
entropy = YARROW_MAX_ENTROPY;
source->estimate[current] = entropy;
}
/* Check for seed/reseed */
switch(current)
{
case YARROW_FAST:
#if YARROW_DEBUG
fprintf(stderr,
"yarrow256_update: source_index = %d,\n"
" fast pool estimate = %d\n",
source_index, source->estimate[YARROW_FAST]);
#endif
if (source->estimate[YARROW_FAST] >= YARROW_FAST_THRESHOLD)
{
yarrow256_fast_reseed(ctx);
return 1;
}
else
return 0;
case YARROW_SLOW:
{
if (!yarrow256_needed_sources(ctx))
{
yarrow256_slow_reseed(ctx);
return 1;
}
else
return 0;
}
default:
abort();
}
}
int
yarrow256_update(struct yarrow256_ctx *ctx,
unsigned source_index, unsigned entropy,
unsigned length, const quint8 *data)
{
enum yarrow_pool_id current;
struct yarrow_source *source;
assert(source_index < ctx->nsources);
if (!length)
/* Nothing happens */
return 0;
source = &ctx->sources[source_index];
if (!ctx->seeded)
/* While seeding, use the slow pool */
current = YARROW_SLOW;
else
{
current = source->next;
source->next = (yarrow_pool_id)!source->next;
}
sha256_update(&ctx->pools[current],data,length);
/* NOTE: We should be careful to avoid overflows in the estimates. */
if (source->estimate[current] < YARROW_MAX_ENTROPY)
{
if (entropy > YARROW_MAX_ENTROPY)
entropy = YARROW_MAX_ENTROPY;
if ( (length < (YARROW_MAX_ENTROPY / YARROW_MULTIPLIER))
&& (entropy > YARROW_MULTIPLIER * length) )
entropy = YARROW_MULTIPLIER * length;
/* FIXME: Calling a more sophisticated estimater should be done
* here. */
entropy += source->estimate[current];
if (entropy > YARROW_MAX_ENTROPY)
entropy = YARROW_MAX_ENTROPY;
source->estimate[current] = entropy;
}
/* Check for seed/reseed */
switch(current)
{
case YARROW_FAST:
#if YARROW_DEBUG
fprintf(stderr,
"yarrow256_update: source_index = %d,\n"
" fast pool estimate = %d\n",
source_index, source->estimate[YARROW_FAST]);
#endif
if (source->estimate[YARROW_FAST] >= YARROW_FAST_THRESHOLD)
{
yarrow_fast_reseed(ctx);
return 1;
}
else
return 0;
case YARROW_SLOW:
{
/* FIXME: This is somewhat inefficient. It would be better to
* either maintain the count, or do this loop only if the
* current source just crossed the threshold. */
if (!yarrow256_needed_sources(ctx))
{
yarrow_slow_reseed(ctx);
ctx->seeded = 1;
return 1;
}
else
return 0;
}
default:
abort();
}
}
