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Implement MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG

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Implement support for MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG.

For test purposes, write an implementation that uses libc rand().

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine
2020-11-13 18:47:18 +01:00
parent 1c49f1ac46
commit 4fc21fdeb6
6 changed files with 97 additions and 5 deletions
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37
library/psa_crypto.c
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@ -6297,6 +6297,10 @@ exit:
*/
static void mbedtls_psa_random_init( mbedtls_psa_random_context_t *rng )
{
#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
memset( rng, 0, sizeof( *rng ) );
#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
/* Set default configuration if
* mbedtls_psa_crypto_configure_entropy_sources() hasn't been called. */
if( rng->entropy_init == NULL )
@ -6316,31 +6320,59 @@ static void mbedtls_psa_random_init( mbedtls_psa_random_context_t *rng )
#endif
mbedtls_psa_drbg_init( mbedtls_psa_random_state( rng ) );
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
}
/** Deinitialize the PSA random generator.
*/
static void mbedtls_psa_random_free( mbedtls_psa_random_context_t *rng )
{
#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
memset( rng, 0, sizeof( *rng ) );
#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
mbedtls_psa_drbg_free( mbedtls_psa_random_state( rng ) );
rng->entropy_free( &rng->entropy );
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
}
/** Seed the PSA random generator.
*/
static psa_status_t mbedtls_psa_random_seed( mbedtls_psa_random_context_t *rng )
{
#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
/* Do nothing: the external RNG seeds itself. */
(void) rng;
return( PSA_SUCCESS );
#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
const unsigned char drbg_seed[] = "PSA";
int ret = mbedtls_psa_drbg_seed( rng, drbg_seed, sizeof( drbg_seed ) - 1 );
return mbedtls_to_psa_error( ret );
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
}
psa_status_t psa_generate_random( uint8_t *output,
size_t output_size )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
GUARD_MODULE_INITIALIZED;
#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
size_t output_length = 0;
psa_status_t status = mbedtls_psa_external_get_random( &global_data.rng,
output, output_size,
&output_length );
if( status != PSA_SUCCESS )
return( status );
/* Breaking up a request into smaller chunks is currently not supported
* for the extrernal RNG interface. */
if( output_length != output_size )
return( PSA_ERROR_INSUFFICIENT_ENTROPY );
return( PSA_SUCCESS );
#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
while( output_size > MBEDTLS_PSA_RANDOM_MAX_REQUEST )
{
ret = mbedtls_psa_get_random(
@ -6355,6 +6387,7 @@ psa_status_t psa_generate_random( uint8_t *output,
ret = mbedtls_psa_get_random( mbedtls_psa_random_state( &global_data.rng ),
output, output_size );
return( mbedtls_to_psa_error( ret ) );
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
}
#if defined(MBEDTLS_PSA_INJECT_ENTROPY)
@ -6586,6 +6619,7 @@ exit:
/* Module setup */
/****************************************************************/
#if !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
psa_status_t mbedtls_psa_crypto_configure_entropy_sources(
void (* entropy_init )( mbedtls_entropy_context *ctx ),
void (* entropy_free )( mbedtls_entropy_context *ctx ) )
@ -6596,6 +6630,7 @@ psa_status_t mbedtls_psa_crypto_configure_entropy_sources(
global_data.rng.entropy_free = entropy_free;
return( PSA_SUCCESS );
}
#endif /* !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) */
void mbedtls_psa_crypto_free( void )
{