/* * Setup and write the ServerKeyExchange parameters */ int dhm_make_params( dhm_context *ctx, int x_size, unsigned char *output, size_t *olen, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) { int ret, n; size_t n1, n2, n3; unsigned char *p; /* * Generate X as large as possible ( < P ) */ n = x_size / sizeof( t_uint ) + 1; mpi_fill_random( &ctx->X, n, f_rng, p_rng ); while( mpi_cmp_mpi( &ctx->X, &ctx->P ) >= 0 ) mpi_shift_r( &ctx->X, 1 ); /* * Calculate GX = G^X mod P */ MPI_CHK( mpi_exp_mod( &ctx->GX, &ctx->G, &ctx->X, &ctx->P , &ctx->RP ) ); if( ( ret = dhm_check_range( &ctx->GX, &ctx->P ) ) != 0 ) return( ret ); /* * export P, G, GX */ #define DHM_MPI_EXPORT(X,n) \ MPI_CHK( mpi_write_binary( X, p + 2, n ) ); \ *p++ = (unsigned char)( n >> 8 ); \ *p++ = (unsigned char)( n ); p += n; n1 = mpi_size( &ctx->P ); n2 = mpi_size( &ctx->G ); n3 = mpi_size( &ctx->GX ); p = output; DHM_MPI_EXPORT( &ctx->P , n1 ); DHM_MPI_EXPORT( &ctx->G , n2 ); DHM_MPI_EXPORT( &ctx->GX, n3 ); *olen = p - output; ctx->len = n1; cleanup: if( ret != 0 ) return( POLARSSL_ERR_DHM_MAKE_PARAMS_FAILED + ret ); return( 0 ); }
/* * Setup and write the ServerKeyExchange parameters */ int dhm_make_params( dhm_context *ctx, int x_size, unsigned char *output, int *olen, int (*f_rng)(void *), void *p_rng ) { int i, ret, n, n1, n2, n3; unsigned char *p; /* * generate X and calculate GX = G^X mod P */ n = x_size / sizeof( t_int ); MPI_CHK( mpi_grow( &ctx->X, n ) ); MPI_CHK( mpi_lset( &ctx->X, 0 ) ); n = x_size >> 3; p = (unsigned char *) ctx->X.p; for( i = 0; i < n; i++ ) *p++ = (unsigned char) f_rng( p_rng ); while( mpi_cmp_mpi( &ctx->X, &ctx->P ) >= 0 ) mpi_shift_r( &ctx->X, 1 ); MPI_CHK( mpi_exp_mod( &ctx->GX, &ctx->G, &ctx->X, &ctx->P , &ctx->RP ) ); /* * export P, G, GX */ #define DHM_MPI_EXPORT(X,n) \ MPI_CHK( mpi_write_binary( X, p + 2, n ) ); \ *p++ = (unsigned char)( n >> 8 ); \ *p++ = (unsigned char)( n ); p += n; n1 = mpi_size( &ctx->P ); n2 = mpi_size( &ctx->G ); n3 = mpi_size( &ctx->GX ); p = output; DHM_MPI_EXPORT( &ctx->P , n1 ); DHM_MPI_EXPORT( &ctx->G , n2 ); DHM_MPI_EXPORT( &ctx->GX, n3 ); *olen = p - output; ctx->len = n1; cleanup: if( ret != 0 ) return( ret | XYSSL_ERR_DHM_MAKE_PARAMS_FAILED ); return( 0 ); }
/* * Setup and write the ServerKeyExchange parameters */ int mbedtls_dhm_make_params( mbedtls_dhm_context *ctx, int x_size, unsigned char *output, size_t *olen, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) { int ret, count = 0; size_t n1, n2, n3; unsigned char *p; if( mbedtls_mpi_cmp_int( &ctx->P, 0 ) == 0 ) return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA ); /* * Generate X as large as possible ( < P ) */ do { mbedtls_mpi_fill_random( &ctx->X, x_size, f_rng, p_rng ); while( mbedtls_mpi_cmp_mpi( &ctx->X, &ctx->P ) >= 0 ) MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &ctx->X, 1 ) ); if( count++ > 10 ) return( MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED ); } while( dhm_check_range( &ctx->X, &ctx->P ) != 0 ); /* * Calculate GX = G^X mod P */ MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->GX, &ctx->G, &ctx->X, &ctx->P , &ctx->RP ) ); if( ( ret = dhm_check_range( &ctx->GX, &ctx->P ) ) != 0 ) return( ret ); /* * export P, G, GX */ #define DHM_MPI_EXPORT(X,n) \ MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( X, p + 2, n ) ); \ *p++ = (unsigned char)( n >> 8 ); \ *p++ = (unsigned char)( n ); p += n; n1 = mbedtls_mpi_size( &ctx->P ); n2 = mbedtls_mpi_size( &ctx->G ); n3 = mbedtls_mpi_size( &ctx->GX ); p = output; DHM_MPI_EXPORT( &ctx->P , n1 ); DHM_MPI_EXPORT( &ctx->G , n2 ); DHM_MPI_EXPORT( &ctx->GX, n3 ); *olen = p - output; ctx->len = n1; cleanup: if( ret != 0 ) return( MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED + ret ); return( 0 ); }