From 7962bfaa798b09598516a81efe32a5eea2ac520b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Manuel=20P=C3=A9gouri=C3=A9-Gonnard?= Date: Tue, 15 Jun 2021 11:29:26 +0200 Subject: [PATCH] Remove "internal RNG" code from ECP MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This is no longer needed, as the RNG param is now mandatory. Signed-off-by: Manuel Pégourié-Gonnard --- library/ecp.c | 224 -------------------------------------------------- 1 file changed, 224 deletions(-) diff --git a/library/ecp.c b/library/ecp.c index 1a78a8f32d..b7a3854757 100644 --- a/library/ecp.c +++ b/library/ecp.c @@ -101,16 +101,6 @@ #include "ecp_internal_alt.h" -#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG) -#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 -#endif /* MBEDTLS_ECP_NO_INTERNAL_RNG */ - #if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \ !defined(inline) && !defined(__cplusplus) #define inline __inline @@ -124,144 +114,6 @@ static unsigned long add_count, dbl_count, mul_count; #endif -#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG) -/* - * Currently ecp_mul() takes a RNG function as an argument, used for - * side-channel protection, but it can be NULL. The initial reasoning was - * that people will pass non-NULL RNG when they care about side-channels, but - * unfortunately we have some APIs that call ecp_mul() with a NULL RNG, with - * no opportunity for the user to do anything about it. - * - * The obvious strategies for addressing that include: - * - change those APIs so that they take RNG arguments; - * - require a global RNG to be available to all crypto modules. - * - * Unfortunately those would break compatibility. So what we do instead is - * have our own internal DRBG instance, seeded from the secret scalar. - * - * The following is a light-weight abstraction layer for doing that with - * HMAC_DRBG (first choice) or CTR_DRBG. - */ - -#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, size_t secret_len ) -{ - int ret; - unsigned char secret_bytes[MBEDTLS_ECP_MAX_BYTES]; - /* 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 ); - - if( secret_len > MBEDTLS_ECP_MAX_BYTES ) - { - ret = MBEDTLS_ERR_ECP_RANDOM_FAILED; - goto cleanup; - } - - MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( secret, - secret_bytes, secret_len ) ); - - ret = mbedtls_hmac_drbg_seed_buf( ctx, md_info, secret_bytes, secret_len ); - -cleanup: - mbedtls_platform_zeroize( secret_bytes, secret_len ); - - return( ret ); -} - -#elif defined(MBEDTLS_CTR_DRBG_C) - -/* DRBG context type */ -typedef mbedtls_ctr_drbg_context ecp_drbg_context; - -/* DRBG context init */ -static inline void ecp_drbg_init( ecp_drbg_context *ctx ) -{ - mbedtls_ctr_drbg_init( ctx ); -} - -/* DRBG context free */ -static inline void ecp_drbg_free( ecp_drbg_context *ctx ) -{ - mbedtls_ctr_drbg_free( ctx ); -} - -/* DRBG function */ -static inline int ecp_drbg_random( void *p_rng, - unsigned char *output, size_t output_len ) -{ - return( mbedtls_ctr_drbg_random( p_rng, output, output_len ) ); -} - -/* - * Since CTR_DRBG doesn't have a seed_buf() function the way HMAC_DRBG does, - * we need to pass an entropy function when seeding. So we use a dummy - * function for that, and pass the actual entropy as customisation string. - * (During seeding of CTR_DRBG the entropy input and customisation string are - * concatenated before being used to update the secret state.) - */ -static int ecp_ctr_drbg_null_entropy(void *ctx, unsigned char *out, size_t len) -{ - (void) ctx; - memset( out, 0, len ); - return( 0 ); -} - -/* DRBG context seeding */ -static int ecp_drbg_seed( ecp_drbg_context *ctx, - const mbedtls_mpi *secret, size_t secret_len ) -{ - int ret; - unsigned char secret_bytes[MBEDTLS_ECP_MAX_BYTES]; - - if( secret_len > MBEDTLS_ECP_MAX_BYTES ) - { - ret = MBEDTLS_ERR_ECP_RANDOM_FAILED; - goto cleanup; - } - - MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( secret, - secret_bytes, secret_len ) ); - - ret = mbedtls_ctr_drbg_seed( ctx, ecp_ctr_drbg_null_entropy, NULL, - secret_bytes, secret_len ); - -cleanup: - mbedtls_platform_zeroize( secret_bytes, secret_len ); - - return( ret ); -} - -#else -#error "Invalid configuration detected. Include check_config.h to ensure that the configuration is valid." -#endif /* DRBG modules */ -#endif /* MBEDTLS_ECP_NO_INTERNAL_RNG */ - #if defined(MBEDTLS_ECP_RESTARTABLE) /* * Maximum number of "basic operations" to be done in a row. @@ -309,10 +161,6 @@ struct mbedtls_ecp_restart_mul ecp_rsm_comb_core, /* ecp_mul_comb_core() */ ecp_rsm_final_norm, /* do the final normalization */ } state; -#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG) - ecp_drbg_context drbg_ctx; - unsigned char drbg_seeded; -#endif }; /* @@ -325,10 +173,6 @@ static void ecp_restart_rsm_init( mbedtls_ecp_restart_mul_ctx *ctx ) ctx->T = NULL; ctx->T_size = 0; ctx->state = ecp_rsm_init; -#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG) - ecp_drbg_init( &ctx->drbg_ctx ); - ctx->drbg_seeded = 0; -#endif } /* @@ -350,10 +194,6 @@ static void ecp_restart_rsm_free( mbedtls_ecp_restart_mul_ctx *ctx ) mbedtls_free( ctx->T ); } -#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG) - ecp_drbg_free( &ctx->drbg_ctx ); -#endif - ecp_restart_rsm_init( ctx ); } @@ -2068,9 +1908,7 @@ static int ecp_mul_comb_core( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R i = d; MBEDTLS_MPI_CHK( ecp_select_comb( grp, R, T, T_size, x[i] ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &R->Z, 1 ) ); -#if defined(MBEDTLS_ECP_NO_INTERNAL_RNG) if( f_rng != 0 ) -#endif MBEDTLS_MPI_CHK( ecp_randomize_jac( grp, R, f_rng, p_rng ) ); } @@ -2204,9 +2042,7 @@ final_norm: * * Avoid the leak by randomizing coordinates before we normalize them. */ -#if defined(MBEDTLS_ECP_NO_INTERNAL_RNG) if( f_rng != 0 ) -#endif MBEDTLS_MPI_CHK( ecp_randomize_jac( grp, RR, f_rng, p_rng ) ); MBEDTLS_MPI_CHK( ecp_normalize_jac( grp, RR ) ); @@ -2286,42 +2122,9 @@ static int ecp_mul_comb( mbedtls_ecp_group *grp, mbedtls_ecp_point *R, size_t d; unsigned char T_size = 0, T_ok = 0; mbedtls_ecp_point *T = NULL; -#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG) - ecp_drbg_context drbg_ctx; - - ecp_drbg_init( &drbg_ctx ); -#endif ECP_RS_ENTER( rsm ); -#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG) - if( f_rng == NULL ) - { - /* Adjust pointers */ - f_rng = &ecp_drbg_random; -#if defined(MBEDTLS_ECP_RESTARTABLE) - if( rs_ctx != NULL && rs_ctx->rsm != NULL ) - p_rng = &rs_ctx->rsm->drbg_ctx; - else -#endif - p_rng = &drbg_ctx; - - /* Initialize internal DRBG if necessary */ -#if defined(MBEDTLS_ECP_RESTARTABLE) - if( rs_ctx == NULL || rs_ctx->rsm == NULL || - rs_ctx->rsm->drbg_seeded == 0 ) -#endif - { - const size_t m_len = ( grp->nbits + 7 ) / 8; - MBEDTLS_MPI_CHK( ecp_drbg_seed( p_rng, m, m_len ) ); - } -#if defined(MBEDTLS_ECP_RESTARTABLE) - if( rs_ctx != NULL && rs_ctx->rsm != NULL ) - rs_ctx->rsm->drbg_seeded = 1; -#endif - } -#endif /* !MBEDTLS_ECP_NO_INTERNAL_RNG */ - /* Is P the base point ? */ #if MBEDTLS_ECP_FIXED_POINT_OPTIM == 1 p_eq_g = ( mbedtls_mpi_cmp_mpi( &P->Y, &grp->G.Y ) == 0 && @@ -2393,10 +2196,6 @@ static int ecp_mul_comb( mbedtls_ecp_group *grp, mbedtls_ecp_point *R, cleanup: -#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG) - ecp_drbg_free( &drbg_ctx ); -#endif - /* does T belong to the group? */ if( T == grp->T ) T = NULL; @@ -2583,23 +2382,8 @@ static int ecp_mul_mxz( mbedtls_ecp_group *grp, mbedtls_ecp_point *R, unsigned char b; mbedtls_ecp_point RP; mbedtls_mpi PX; -#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG) - ecp_drbg_context drbg_ctx; - - ecp_drbg_init( &drbg_ctx ); -#endif mbedtls_ecp_point_init( &RP ); mbedtls_mpi_init( &PX ); -#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG) - if( f_rng == NULL ) - { - const size_t m_len = ( grp->nbits + 7 ) / 8; - MBEDTLS_MPI_CHK( ecp_drbg_seed( &drbg_ctx, m, m_len ) ); - f_rng = &ecp_drbg_random; - p_rng = &drbg_ctx; - } -#endif /* !MBEDTLS_ECP_NO_INTERNAL_RNG */ - /* Save PX and read from P before writing to R, in case P == R */ MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &PX, &P->X ) ); MBEDTLS_MPI_CHK( mbedtls_ecp_copy( &RP, P ) ); @@ -2613,9 +2397,7 @@ static int ecp_mul_mxz( mbedtls_ecp_group *grp, mbedtls_ecp_point *R, MOD_ADD( RP.X ); /* Randomize coordinates of the starting point */ -#if defined(MBEDTLS_ECP_NO_INTERNAL_RNG) if( f_rng != NULL ) -#endif MBEDTLS_MPI_CHK( ecp_randomize_mxz( grp, &RP, f_rng, p_rng ) ); /* Loop invariant: R = result so far, RP = R + P */ @@ -2648,18 +2430,12 @@ static int ecp_mul_mxz( mbedtls_ecp_group *grp, mbedtls_ecp_point *R, * * Avoid the leak by randomizing coordinates before we normalize them. */ -#if defined(MBEDTLS_ECP_NO_INTERNAL_RNG) if( f_rng != NULL ) -#endif MBEDTLS_MPI_CHK( ecp_randomize_mxz( grp, R, f_rng, p_rng ) ); MBEDTLS_MPI_CHK( ecp_normalize_mxz( grp, R ) ); cleanup: -#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG) - ecp_drbg_free( &drbg_ctx ); -#endif - mbedtls_ecp_point_free( &RP ); mbedtls_mpi_free( &PX ); return( ret );