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Merge pull request #293 from gilles-peskine-arm/entropy-min

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Always gather MBEDTLS_ENTROPY_BLOCK_SIZE bytes of entropy
This commit is contained in:
Gilles Peskine
2019-11-26 18:43:45 +01:00
committed by GitHub
parent 0f212ff145 cbd91e013c
commit 8f4df81506
3 changed files with 151 additions and 41 deletions
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14
library/entropy.c
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@ -327,7 +327,8 @@ int mbedtls_entropy_gather( mbedtls_entropy_context *ctx )
int mbedtls_entropy_func( void *data, unsigned char *output, size_t len )
{
int ret, count = 0, i, done;
int ret, count = 0, i, thresholds_reached;
size_t strong_size;
mbedtls_entropy_context *ctx = (mbedtls_entropy_context *) data;
unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
@ -365,12 +366,17 @@ int mbedtls_entropy_func( void *data, unsigned char *output, size_t len )
if( ( ret = entropy_gather_internal( ctx ) ) != 0 )
goto exit;
done = 1;
thresholds_reached = 1;
strong_size = 0;
for( i = 0; i < ctx->source_count; i++ )
{
if( ctx->source[i].size < ctx->source[i].threshold )
done = 0;
thresholds_reached = 0;
if( ctx->source[i].strong == MBEDTLS_ENTROPY_SOURCE_STRONG )
strong_size += ctx->source[i].size;
}
}
while( ! done );
while( ! thresholds_reached || strong_size < MBEDTLS_ENTROPY_BLOCK_SIZE );
memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );