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Use HMAC_DRBG by default for ECP internal DRBG

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It results in smaller code than using CTR_DRBG (64 bytes smaller on ARMv6-M
with arm-none-eabi-gcc 7.3.1), so let's use this by default when both are
available.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
This commit is contained in:
Manuel Pégourié-Gonnard 2020-06-04 12:32:14 +02:00
parent 22b1de3097
commit d53ef2ffd1
1 changed files with 43 additions and 41 deletions
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84
library/ecp.c
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@ -106,10 +106,10 @@
#include "mbedtls/ecp_internal.h"
#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
#if defined(MBEDTLS_CTR_DRBG_C)
#include "mbedtls/ctr_drbg.h"
#elif defined(MBEDTLS_HMAC_DRBG_C)
#if defined(MBEDTLS_HMAC_DRBG_C)
#include "mbedtls/hmac_drbg.h"
#elif defined(MBEDTLS_CTR_DRBG_C)
#include "mbedtls/ctr_drbg.h"
#else
#error "Invalid configuration detected. Include check_config.h to ensure that the configuration is valid."
#endif
@ -144,10 +144,48 @@ static unsigned long add_count, dbl_count, mul_count;
* have our own internal DRBG instance, seeded from the secret scalar.
*
* The following is a light-weight abstraction layer for doing that with
* CTR_DRBG or HMAC_DRBG.
* HMAC_DRBG (first choice) or CTR_DRBG.
*/
#if defined(MBEDTLS_CTR_DRBG_C)
#if defined(MBEDTLS_HMAC_DRBG_C)
/* DRBG context type */
typedef mbedtls_hmac_drbg_context ecp_drbg_context;
/* DRBG context init */
static inline void ecp_drbg_init( ecp_drbg_context *ctx )
{
mbedtls_hmac_drbg_init( ctx );
}
/* DRBG context free */
static inline void ecp_drbg_free( ecp_drbg_context *ctx )
{
mbedtls_hmac_drbg_free( ctx );
}
/* DRBG function */
static inline int ecp_drbg_random( void *p_rng,
unsigned char *output, size_t output_len )
{
return( mbedtls_hmac_drbg_random( p_rng, output, output_len ) );
}
/* DRBG context seeding */
static int ecp_drbg_seed( ecp_drbg_context *ctx, const mbedtls_mpi *secret )
{
const unsigned char *secret_p = (const unsigned char *) secret->p;
const size_t secret_size = secret->n * sizeof( mbedtls_mpi_uint );
/* The list starts with strong hashes */
const mbedtls_md_type_t md_type = mbedtls_md_list()[0];
const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( md_type );
return( mbedtls_hmac_drbg_seed_buf( ctx, md_info, secret_p, secret_size ) );
}
#elif defined(MBEDTLS_CTR_DRBG_C)
/* DRBG context type */
typedef mbedtls_ctr_drbg_context ecp_drbg_context;
@ -194,42 +232,6 @@ static int ecp_drbg_seed( ecp_drbg_context *ctx, const mbedtls_mpi *secret )
secret_p, secret_size ) );
}
#elif defined(MBEDTLS_HMAC_DRBG_C)
/* DRBG context type */
typedef mbedtls_hmac_drbg_context ecp_drbg_context;
/* DRBG context init */
static inline void ecp_drbg_init( ecp_drbg_context *ctx )
{
mbedtls_hmac_drbg_init( ctx );
}
/* DRBG context free */
static inline void ecp_drbg_free( ecp_drbg_context *ctx )
{
mbedtls_hmac_drbg_free( ctx );
}
/* DRBG function */
static inline int ecp_drbg_random( void *p_rng,
unsigned char *output, size_t output_len )
{
return( mbedtls_hmac_drbg_random( p_rng, output, output_len ) );
}
/* DRBG context seeding */
static int ecp_drbg_seed( ecp_drbg_context *ctx, const mbedtls_mpi *secret )
{
const unsigned char *secret_p = (const unsigned char *) secret->p;
const size_t secret_size = secret->n * sizeof( mbedtls_mpi_uint );
/* The list starts with strong hashes */
const mbedtls_md_type_t md_type = mbedtls_md_list()[0];
const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( md_type );
return( mbedtls_hmac_drbg_seed_buf( ctx, md_info, secret_p, secret_size ) );
}
#else
#error "Invalid configuration detected. Include check_config.h to ensure that the configuration is valid."
#endif /* DRBG modules */