PSA: support HMAC_DRBG

Support using HMAC_DRBG instead of CTR_DRBG in the PSA subsystem.

Use HMAC_DRBG if CTR_DRBG is available. Choose between SHA-256 and
SHA-512 based on availability.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine 2020-11-13 21:31:17 +01:00
parent 4fc21fdeb6
commit 82e57d1611
6 changed files with 91 additions and 13 deletions

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@ -573,7 +573,7 @@
#endif
#if defined(MBEDTLS_PSA_CRYPTO_C) && \
!( ( defined(MBEDTLS_CTR_DRBG_C) && \
!( ( ( defined(MBEDTLS_CTR_DRBG_C) || defined(MBEDTLS_HMAC_DRBG_C) ) && \
defined(MBEDTLS_ENTROPY_C) ) || \
defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) )
#error "MBEDTLS_PSA_CRYPTO_C defined, but not all prerequisites (missing RNG)"

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@ -3146,6 +3146,7 @@
* Module: library/psa_crypto.c
*
* Requires: either MBEDTLS_CTR_DRBG_C and MBEDTLS_ENTROPY_C,
* or MBEDTLS_HMAC_DRBG_C and MBEDTLS_ENTROPY_C,
* or MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG.
*
*/

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@ -63,7 +63,6 @@
#include "mbedtls/cipher.h"
#include "mbedtls/ccm.h"
#include "mbedtls/cmac.h"
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/des.h"
#include "mbedtls/ecdh.h"
#include "mbedtls/ecp.h"
@ -214,6 +213,8 @@ psa_status_t mbedtls_to_psa_error( int ret )
case MBEDTLS_ERR_CMAC_HW_ACCEL_FAILED:
return( PSA_ERROR_HARDWARE_FAILURE );
#if !( defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) || \
defined(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE) )
case MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED:
return( PSA_ERROR_INSUFFICIENT_ENTROPY );
case MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG:
@ -221,6 +222,7 @@ psa_status_t mbedtls_to_psa_error( int ret )
return( PSA_ERROR_NOT_SUPPORTED );
case MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR:
return( PSA_ERROR_INSUFFICIENT_ENTROPY );
#endif
case MBEDTLS_ERR_DES_INVALID_INPUT_LENGTH:
return( PSA_ERROR_NOT_SUPPORTED );
@ -239,6 +241,17 @@ psa_status_t mbedtls_to_psa_error( int ret )
case MBEDTLS_ERR_GCM_HW_ACCEL_FAILED:
return( PSA_ERROR_HARDWARE_FAILURE );
#if !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) && \
defined(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE)
case MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED:
return( PSA_ERROR_INSUFFICIENT_ENTROPY );
case MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG:
case MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG:
return( PSA_ERROR_NOT_SUPPORTED );
case MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR:
return( PSA_ERROR_INSUFFICIENT_ENTROPY );
#endif
case MBEDTLS_ERR_MD2_HW_ACCEL_FAILED:
case MBEDTLS_ERR_MD4_HW_ACCEL_FAILED:
case MBEDTLS_ERR_MD5_HW_ACCEL_FAILED:

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@ -50,15 +50,48 @@ static inline void *mbedtls_psa_random_state( mbedtls_psa_random_context_t *rng
#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
/* Currently, the only supported RNG is Mbed TLS's CTR_DRBG seeded with
* mbedtls_entropy_func(). */
/* Choose a DRBG based on configuration and availability */
#if defined(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE)
#include "mbedtls/hmac_drbg.h"
#elif defined(MBEDTLS_CTR_DRBG_C)
#include "mbedtls/ctr_drbg.h"
#elif defined(MBEDTLS_HMAC_DRBG_C)
#include "mbedtls/hmac_drbg.h"
#if defined(MBEDTLS_SHA512_C) && defined(MBEDTLS_SHA256_C)
#include <limits.h>
#if SIZE_MAX > 0xffffffff
/* Looks like a 64-bit system, so prefer SHA-512. */
#define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA512
#else
/* Looks like a 32-bit system, so prefer SHA-256. */
#define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA256
#endif
#elif defined(MBEDTLS_SHA512_C)
#define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA512
#elif defined(MBEDTLS_SHA256_C)
#define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA256
#else
#error "No hash algorithm available for HMAC_DBRG."
#endif
#else
#error "No DRBG module available for the psa_crypto module."
#endif
#include "mbedtls/entropy.h"
/** The type of the PSA DRBG context.
*/
#if defined(MBEDTLS_CTR_DRBG_C)
typedef mbedtls_ctr_drbg_context mbedtls_psa_drbg_context_t;
#elif defined(MBEDTLS_HMAC_DRBG_C)
typedef mbedtls_hmac_drbg_context mbedtls_psa_drbg_context_t;
#endif
/** Initialize the PSA DRBG.
*
@ -66,7 +99,11 @@ typedef mbedtls_ctr_drbg_context mbedtls_psa_drbg_context_t;
*/
static inline void mbedtls_psa_drbg_init( mbedtls_psa_drbg_context_t *p_rng )
{
#if defined(MBEDTLS_CTR_DRBG_C)
mbedtls_ctr_drbg_init( p_rng );
#elif defined(MBEDTLS_HMAC_DRBG_C)
mbedtls_hmac_drbg_init( p_rng );
#endif
}
/** Deinitialize the PSA DRBG.
@ -75,7 +112,11 @@ static inline void mbedtls_psa_drbg_init( mbedtls_psa_drbg_context_t *p_rng )
*/
static inline void mbedtls_psa_drbg_free( mbedtls_psa_drbg_context_t *p_rng )
{
#if defined(MBEDTLS_CTR_DRBG_C)
mbedtls_ctr_drbg_free( p_rng );
#elif defined(MBEDTLS_HMAC_DRBG_C)
mbedtls_hmac_drbg_free( p_rng );
#endif
}
/** The type of the PSA random generator context.
@ -97,7 +138,7 @@ typedef struct
* that require a random generator. Use mbedtls_psa_random_state() to
* obtain the \p p_rng parameter.
*
* \param p_rng The CTR_DRBG context. This must be
* \param p_rng The DRBG context. This must be
* mbedtls_psa_random_state( \c rng )
* where \c rng is a pointer to a
* ::mbedtls_psa_random_context_t structure.
@ -105,21 +146,29 @@ typedef struct
* \param output_len The length of the buffer in bytes.
* It must be at most #MBEDTLS_PSA_RANDOM_MAX_REQUEST.
*
* \return \c 0 on success.
* \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or
* #MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG on failure.
* \retval \c 0 on success.
* \return \c MBEDTLS_ERR_xxx_DRBG_xxx or
* \c MBEDTLS_ERR_PLATFORM_xxx on failure.
*/
static inline int mbedtls_psa_get_random( void *p_rng,
unsigned char *output,
size_t output_len )
{
#if defined(MBEDTLS_CTR_DRBG_C)
return( mbedtls_ctr_drbg_random( p_rng, output, output_len ) );
#elif defined(MBEDTLS_HMAC_DRBG_C)
return( mbedtls_hmac_drbg_random( p_rng, output, output_len ) );
#endif
}
/** The maximum number of bytes that mbedtls_psa_get_random() is expected to
* return.
*/
#if defined(MBEDTLS_CTR_DRBG_C)
#define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_CTR_DRBG_MAX_REQUEST
#elif defined(MBEDTLS_HMAC_DRBG_C)
#define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_HMAC_DRBG_MAX_REQUEST
#endif
/** Retrieve the DRBG state from the PSA RNG state.
*
@ -133,7 +182,6 @@ static inline mbedtls_psa_drbg_context_t *mbedtls_psa_random_state(
return( &rng->drbg );
}
/** Seed the PSA DRBG.
*
* \param rng DRBG context to be seeded.
@ -149,10 +197,20 @@ static inline int mbedtls_psa_drbg_seed(
mbedtls_psa_random_context_t *rng,
const unsigned char *custom, size_t len )
{
#if defined(MBEDTLS_CTR_DRBG_C)
return( mbedtls_ctr_drbg_seed( mbedtls_psa_random_state( rng ),
mbedtls_entropy_func,
&rng->entropy,
custom, len ) );
#elif defined(MBEDTLS_HMAC_DRBG_C)
const mbedtls_md_info_t *md_info =
mbedtls_md_info_from_type( MBEDTLS_PSA_HMAC_DRBG_MD_TYPE );
return( mbedtls_hmac_drbg_seed( mbedtls_psa_random_state( rng ),
md_info,
mbedtls_entropy_func,
&rng->entropy,
custom, len ) );
#endif
}
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */

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@ -915,10 +915,6 @@ component_test_no_ctr_drbg () {
msg "build: Full minus CTR_DRBG"
scripts/config.py full
scripts/config.py unset MBEDTLS_CTR_DRBG_C
scripts/config.py unset MBEDTLS_PSA_CRYPTO_C # requires CTR_DRBG
scripts/config.py unset MBEDTLS_PSA_CRYPTO_STORAGE_C # requires PSA Crypto
scripts/config.py unset MBEDTLS_PSA_CRYPTO_SE_C # requires PSA Crypto
scripts/config.py unset MBEDTLS_USE_PSA_CRYPTO # requires PSA Crypto
CC=gcc cmake -D CMAKE_BUILD_TYPE:String=Asan .
make

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@ -11,11 +11,21 @@
#define ENTROPY_MIN_NV_SEED_SIZE \
MAX(MBEDTLS_ENTROPY_MIN_PLATFORM, MBEDTLS_ENTROPY_BLOCK_SIZE)
#include "psa_crypto_random.h"
#if defined(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE)
/* PSA crypto uses the HMAC_DRBG module. It reads from the entropy source twice:
* once for the initial entropy and once for a nonce. The nonce length is
* half the entropy length. For SHA-256, SHA-384 or SHA-512, the
* entropy length is 256 per the documentation of mbedtls_hmac_drbg_seed(),
* and PSA crypto doesn't support other hashes for HMAC_DRBG. */
#define ENTROPY_NONCE_LEN ( 256 / 2 )
#else
/* PSA crypto uses the CTR_DRBG module. In some configurations, it needs
* to read from the entropy source twice: once for the initial entropy
* and once for a nonce. */
#include "mbedtls/ctr_drbg.h"
#define ENTROPY_NONCE_LEN MBEDTLS_CTR_DRBG_ENTROPY_NONCE_LEN
#endif
#if !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)