commit 02b5705aa37613d83c97aa2f84b8d66b10b60d3d
author Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com> Tue Jun 15 11:29:26 2021 +0200
committer Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com> Thu Jun 17 09:38:38 2021 +0200
tree c2265dde893cee0849ac656f3c1a8494baa78349
parent 7962bfaa798b09598516a81efe32a5eea2ac520b

Simplify internal code

We know that Montgomery multiplication will never be called without an
RNG, so make that clear from the beginning of the function.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>

library/ecp.c

diff --git a/library/ecp.c b/library/ecp.c
index b7a3854..8f6e988 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -2384,6 +2384,9 @@
     mbedtls_mpi PX;
     mbedtls_ecp_point_init( &RP ); mbedtls_mpi_init( &PX );
 
+    if( f_rng == NULL )
+        return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
     /* 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 ) );
@@ -2397,8 +2400,7 @@
     MOD_ADD( RP.X );
 
     /* Randomize coordinates of the starting point */
-    if( f_rng != NULL )
-        MBEDTLS_MPI_CHK( ecp_randomize_mxz( grp, &RP, f_rng, p_rng ) );
+    MBEDTLS_MPI_CHK( ecp_randomize_mxz( grp, &RP, f_rng, p_rng ) );
 
     /* Loop invariant: R = result so far, RP = R + P */
     i = mbedtls_mpi_bitlen( m ); /* one past the (zero-based) most significant bit */
@@ -2430,9 +2432,7 @@
      *
      * Avoid the leak by randomizing coordinates before we normalize them.
      */
-    if( f_rng != NULL )
-        MBEDTLS_MPI_CHK( ecp_randomize_mxz( grp, R, f_rng, p_rng ) );
-
+    MBEDTLS_MPI_CHK( ecp_randomize_mxz( grp, R, f_rng, p_rng ) );
     MBEDTLS_MPI_CHK( ecp_normalize_mxz( grp, R ) );
 
 cleanup: