commit bfa1972b4fa47c9c6ce0230829109b42c4bc2ff2
author Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com> Wed Aug 23 17:39:18 2017 +0200
committer Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com> Wed Aug 23 18:20:17 2017 +0200
tree 5ae320146c8ef593fd2b596e06fb115d975501d4
parent 28d162829b2a136f9e57b9b260ea2f43315fb597

Remove redundant checks, save a few muls

ecp_mul() already checks for this, and this check is not going away, so no
need to do it twice (didn't even result in better error reporting)

library/ecdh.c

diff --git a/library/ecdh.c b/library/ecdh.c
index b8a7dbf..25a788b 100644
--- a/library/ecdh.c
+++ b/library/ecdh.c
@@ -87,11 +87,6 @@
 
     mbedtls_ecp_point_init( &P );
 
-    /*
-     * Make sure Q is a valid pubkey before using it
-     */
-    MBEDTLS_MPI_CHK( mbedtls_ecp_check_pubkey( grp, Q ) );
-
     MBEDTLS_MPI_CHK( mbedtls_ecp_mul_restartable( grp, &P, d, Q,
                                                   f_rng, p_rng, rs_ctx ) );
 

library/ecdsa.c

diff --git a/library/ecdsa.c b/library/ecdsa.c
index 835d3de..3fddc4e 100644
--- a/library/ecdsa.c
+++ b/library/ecdsa.c
@@ -499,13 +499,6 @@
     }
 
     /*
-     * Additional precaution: make sure Q is valid
-     * For ops count, group that together with step 4
-     */
-    ECDSA_BUDGET( MBEDTLS_ECP_OPS_CHK + MBEDTLS_ECP_OPS_INV + 2 );
-    MBEDTLS_MPI_CHK( mbedtls_ecp_check_pubkey( grp, Q ) );
-
-    /*
      * Step 3: derive MPI from hashed message
      */
     MBEDTLS_MPI_CHK( derive_mpi( grp, &e, buf, blen ) );
@@ -513,6 +506,8 @@
     /*
      * Step 4: u1 = e / s mod n, u2 = r / s mod n
      */
+    ECDSA_BUDGET( MBEDTLS_ECP_OPS_CHK + MBEDTLS_ECP_OPS_INV + 2 );
+
     MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &s_inv, s, &grp->N ) );
 
     MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( pu1, &e, &s_inv ) );