Add a concept of entropy source strength.

The main goal is, we want and error if cycle counter is the only source.
parent 3f77dfbd
......@@ -53,7 +53,8 @@
#define MBEDTLS_ERR_ENTROPY_SOURCE_FAILED -0x003C /**< Critical entropy source failure. */
#define MBEDTLS_ERR_ENTROPY_MAX_SOURCES -0x003E /**< No more sources can be added. */
#define MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED -0x0040 /**< No sources have been added to poll. */
#define MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR -0x0058 /**< Read/write error in file. */
#define MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE -0x003D /**< No strong sources have been added to poll. */
#define MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR -0x003F /**< Read/write error in file. */
/**
* \name SECTION: Module settings
......@@ -82,6 +83,9 @@
#define MBEDTLS_ENTROPY_MAX_SEED_SIZE 1024 /**< Maximum size of seed we read from seed file */
#define MBEDTLS_ENTROPY_SOURCE_MANUAL MBEDTLS_ENTROPY_MAX_SOURCES
#define MBEDTLS_ENTROPY_SOURCE_STRONG 1 /**< Entropy source is strong */
#define MBEDTLS_ENTROPY_SOURCE_WEAK 0 /**< Entropy source is weak */
#ifdef __cplusplus
extern "C" {
#endif
......@@ -109,6 +113,7 @@ typedef struct
void * p_source; /**< The callback data pointer */
size_t size; /**< Amount received in bytes */
size_t threshold; /**< Minimum bytes required before release */
int strong; /**< Is the source strong? */
}
mbedtls_entropy_source_state;
......@@ -156,12 +161,17 @@ void mbedtls_entropy_free( mbedtls_entropy_context *ctx );
* \param p_source Function data
* \param threshold Minimum required from source before entropy is released
* ( with mbedtls_entropy_func() ) (in bytes)
* \param strong MBEDTLS_ENTROPY_SOURCE_STRONG or
* MBEDTSL_ENTROPY_SOURCE_WEAK.
* At least one strong source needs to be added.
* Weaker sources (such as the cycle counter) can be used as
* a complement.
*
* \return 0 if successful or MBEDTLS_ERR_ENTROPY_MAX_SOURCES
*/
int mbedtls_entropy_add_source( mbedtls_entropy_context *ctx,
mbedtls_entropy_f_source_ptr f_source, void *p_source,
size_t threshold );
size_t threshold, int strong );
/**
* \brief Trigger an extra gather poll for the accumulator
......
......@@ -61,9 +61,8 @@
* PADLOCK 1 0x0030-0x0030
* DES 1 0x0032-0x0032
* CTR_DBRG 4 0x0034-0x003A
* ENTROPY 3 0x003C-0x0040
* ENTROPY 3 0x003C-0x0040 0x003D-0x003F
* NET 9 0x0042-0x0052 0x0043-0x0043
* ENTROPY 1 0x0058-0x0058
* ASN1 7 0x0060-0x006C
* PBKDF2 1 0x007C-0x007C
* HMAC_DRBG 4 0x0003-0x0009
......
......@@ -77,18 +77,23 @@ void mbedtls_entropy_init( mbedtls_entropy_context *ctx )
#if !defined(MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES)
#if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)
mbedtls_entropy_add_source( ctx, mbedtls_platform_entropy_poll, NULL,
MBEDTLS_ENTROPY_MIN_PLATFORM );
MBEDTLS_ENTROPY_MIN_PLATFORM,
MBEDTLS_ENTROPY_SOURCE_STRONG );
#endif
#if defined(MBEDTLS_TIMING_C)
mbedtls_entropy_add_source( ctx, mbedtls_hardclock_poll, NULL, MBEDTLS_ENTROPY_MIN_HARDCLOCK );
mbedtls_entropy_add_source( ctx, mbedtls_hardclock_poll, NULL,
MBEDTLS_ENTROPY_MIN_HARDCLOCK,
MBEDTLS_ENTROPY_SOURCE_WEAK );
#endif
#if defined(MBEDTLS_HAVEGE_C)
mbedtls_entropy_add_source( ctx, mbedtls_havege_poll, &ctx->havege_data,
MBEDTLS_ENTROPY_MIN_HAVEGE );
MBEDTLS_ENTROPY_MIN_HAVEGE,
MBEDTLS_ENTROPY_SOURCE_STRONG );
#endif
#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
mbedtls_entropy_add_source( ctx, mbedtls_hardware_poll, NULL
MBEDTLS_ENTROPY_MIN_HARDWARE );
MBEDTLS_ENTROPY_MIN_HARDWARE,
MBEDTLS_ENTROPY_SOURCE_STRONG );
#endif
#endif /* MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES */
}
......@@ -106,7 +111,7 @@ void mbedtls_entropy_free( mbedtls_entropy_context *ctx )
int mbedtls_entropy_add_source( mbedtls_entropy_context *ctx,
mbedtls_entropy_f_source_ptr f_source, void *p_source,
size_t threshold )
size_t threshold, int strong )
{
int index, ret = 0;
......@@ -122,9 +127,10 @@ int mbedtls_entropy_add_source( mbedtls_entropy_context *ctx,
goto exit;
}
ctx->source[index].f_source = f_source;
ctx->source[index].p_source = p_source;
ctx->source[index].f_source = f_source;
ctx->source[index].p_source = p_source;
ctx->source[index].threshold = threshold;
ctx->source[index].strong = strong;
ctx->source_count++;
......@@ -198,7 +204,7 @@ int mbedtls_entropy_update_manual( mbedtls_entropy_context *ctx,
*/
static int entropy_gather_internal( mbedtls_entropy_context *ctx )
{
int ret, i;
int ret, i, have_one_strong = 0;
unsigned char buf[MBEDTLS_ENTROPY_MAX_GATHER];
size_t olen;
......@@ -210,6 +216,9 @@ static int entropy_gather_internal( mbedtls_entropy_context *ctx )
*/
for( i = 0; i < ctx->source_count; i++ )
{
if( ctx->source[i].strong == MBEDTLS_ENTROPY_SOURCE_STRONG )
have_one_strong = 1;
olen = 0;
if( ( ret = ctx->source[i].f_source( ctx->source[i].p_source,
buf, MBEDTLS_ENTROPY_MAX_GATHER, &olen ) ) != 0 )
......@@ -227,6 +236,9 @@ static int entropy_gather_internal( mbedtls_entropy_context *ctx )
}
}
if( have_one_strong == 0 )
return( MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE );
return( 0 );
}
......@@ -424,11 +436,12 @@ int mbedtls_entropy_self_test( int verbose )
mbedtls_entropy_init( &ctx );
/* First do a gather to mek sure we have default sources */
/* First do a gather to make sure we have default sources */
if( ( ret = mbedtls_entropy_gather( &ctx ) ) != 0 )
goto cleanup;
ret = mbedtls_entropy_add_source( &ctx, entropy_dummy_source, NULL, 16 );
ret = mbedtls_entropy_add_source( &ctx, entropy_dummy_source, NULL, 16,
MBEDTLS_ENTROPY_SOURCE_WEAK );
if( ret != 0 )
goto cleanup;
......
......@@ -286,7 +286,8 @@ int main( int argc, char *argv[] )
if( opt.use_dev_random )
{
if( ( ret = mbedtls_entropy_add_source( &entropy, dev_random_entropy_poll,
NULL, DEV_RANDOM_THRESHOLD ) ) != 0 )
NULL, DEV_RANDOM_THRESHOLD,
MBEDTLS_ENTROPY_SOURCE_STRONG ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_entropy_add_source returned -0x%04x\n", -ret );
goto exit;
......
......@@ -68,9 +68,11 @@ void entropy_too_many_sources( )
* since we don't know how many sources were automatically added.
*/
for( i = 0; i < MBEDTLS_ENTROPY_MAX_SOURCES; i++ )
(void) mbedtls_entropy_add_source( &ctx, entropy_dummy_source, NULL, 16 );
(void) mbedtls_entropy_add_source( &ctx, entropy_dummy_source, NULL,
16, MBEDTLS_ENTROPY_SOURCE_WEAK );
TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source, NULL, 16 )
TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source, NULL,
16, MBEDTLS_ENTROPY_SOURCE_WEAK )
== MBEDTLS_ERR_ENTROPY_MAX_SOURCES );
exit:
......@@ -116,7 +118,9 @@ void entropy_source_fail( char *path )
mbedtls_entropy_init( &ctx );
TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source, &fail, 16 )
TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source,
&fail, 16,
MBEDTLS_ENTROPY_SOURCE_WEAK )
== 0 );
TEST_ASSERT( mbedtls_entropy_func( &ctx, buf, sizeof( buf ) )
......@@ -147,7 +151,8 @@ void entropy_threshold( int threshold, int chunk_size, int result )
mbedtls_entropy_init( &ctx );
TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source,
&chunk_size, threshold ) == 0 );
&chunk_size, threshold,
MBEDTLS_ENTROPY_SOURCE_WEAK ) == 0 );
entropy_dummy_calls = 0;
ret = mbedtls_entropy_func( &ctx, buf, sizeof( buf ) );
......
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