diff --git a/library/ecdsa.c b/library/ecdsa.c index 14854ffac..b8aef5d30 100644 --- a/library/ecdsa.c +++ b/library/ecdsa.c @@ -225,7 +225,7 @@ static int ecdsa_sign_restartable( mbedtls_ecp_group *grp, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, mbedtls_ecdsa_restart_ctx *rs_ctx ) { - int ret, key_tries, sign_tries, blind_tries; + int ret, key_tries, sign_tries; mbedtls_ecp_point R; mbedtls_mpi k, e, t; @@ -271,7 +271,10 @@ static int ecdsa_sign_restartable( mbedtls_ecp_group *grp, goto cleanup; } - MBEDTLS_MPI_CHK( mbedtls_ecp_gen_keypair( grp, &k, &R, f_rng, p_rng ) ); + MBEDTLS_MPI_CHK( mbedtls_ecp_gen_privkey( grp, &k, f_rng, p_rng ) ); + + MBEDTLS_MPI_CHK( mbedtls_ecp_mul( grp, &R, &k, &grp->G, + f_rng, p_rng ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( r, &R.X, &grp->N ) ); } while( mbedtls_mpi_cmp_int( r, 0 ) == 0 ); @@ -285,19 +288,7 @@ static int ecdsa_sign_restartable( mbedtls_ecp_group *grp, * Generate a random value to blind inv_mod in next step, * avoiding a potential timing leak. */ - blind_tries = 0; - do - { - size_t n_size = ( grp->nbits + 7 ) / 8; - MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &t, n_size, f_rng, p_rng ) ); - MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &t, 8 * n_size - grp->nbits ) ); - - /* See mbedtls_ecp_gen_keypair() */ - if( ++blind_tries > 30 ) - return( MBEDTLS_ERR_ECP_RANDOM_FAILED ); - } - while( mbedtls_mpi_cmp_int( &t, 1 ) < 0 || - mbedtls_mpi_cmp_mpi( &t, &grp->N ) >= 0 ); + MBEDTLS_MPI_CHK( mbedtls_ecp_gen_privkey( grp, &t, f_rng, p_rng ) ); /* * Step 6: compute s = (e + r * d) / k = t (e + rd) / (kt) mod n