From 82e57d1611877b7d27f7194cb34528b8eca54ea2 Mon Sep 17 00:00:00 2001 From: Gilles Peskine Date: Fri, 13 Nov 2020 21:31:17 +0100 Subject: [PATCH] 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 --- include/mbedtls/check_config.h | 2 +- include/mbedtls/config.h | 1 + library/psa_crypto.c | 15 +++- library/psa_crypto_random.h | 72 +++++++++++++++++-- tests/scripts/all.sh | 4 -- .../test_suite_psa_crypto_init.function | 10 +++ 6 files changed, 91 insertions(+), 13 deletions(-) diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h index 949727994..939ec6c65 100644 --- a/include/mbedtls/check_config.h +++ b/include/mbedtls/check_config.h @@ -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)" diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h index 58d78075d..c022a6174 100644 --- a/include/mbedtls/config.h +++ b/include/mbedtls/config.h @@ -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. * */ diff --git a/library/psa_crypto.c b/library/psa_crypto.c index 410d6a191..66c4f7de0 100644 --- a/library/psa_crypto.c +++ b/library/psa_crypto.c @@ -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: diff --git a/library/psa_crypto_random.h b/library/psa_crypto_random.h index 2e7f94d4c..0f13c1392 100644 --- a/library/psa_crypto_random.h +++ b/library/psa_crypto_random.h @@ -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 +#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 */ diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh index 2bb2216c9..30ec62f86 100755 --- a/tests/scripts/all.sh +++ b/tests/scripts/all.sh @@ -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 diff --git a/tests/suites/test_suite_psa_crypto_init.function b/tests/suites/test_suite_psa_crypto_init.function index 867e4236c..16e44c7af 100644 --- a/tests/suites/test_suite_psa_crypto_init.function +++ b/tests/suites/test_suite_psa_crypto_init.function @@ -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)