diff --git a/library/ecdh.c b/library/ecdh.c
index d76596e..8ef02f5 100644
--- a/library/ecdh.c
+++ b/library/ecdh.c
@@ -50,7 +50,9 @@
  * Compute shared secret (SEC1 3.3.1)
  */
 int ecdh_compute_shared( const ecp_group *grp, mpi *z,
-                         const ecp_point *Q, const mpi *d )
+                         const ecp_point *Q, const mpi *d,
+                         int (*f_rng)(void *, unsigned char *, size_t),
+                         void *p_rng )
 {
     int ret;
     ecp_point P;
@@ -62,7 +64,7 @@
      */
     MPI_CHK( ecp_check_pubkey( grp, Q ) );
 
-    MPI_CHK( ecp_mul( grp, &P, d, Q ) );
+    MPI_CHK( ecp_mul( grp, &P, d, Q, f_rng, p_rng ) );
 
     if( ecp_is_zero( &P ) )
     {
@@ -202,16 +204,20 @@
  * Derive and export the shared secret
  */
 int ecdh_calc_secret( ecdh_context *ctx, size_t *olen,
-                      unsigned char *buf, size_t blen )
+                      unsigned char *buf, size_t blen,
+                      int (*f_rng)(void *, unsigned char *, size_t),
+                      void *p_rng )
 {
     int ret;
 
     if( ctx == NULL )
         return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
 
-    if( ( ret = ecdh_compute_shared( &ctx->grp, &ctx->z, &ctx->Qp, &ctx->d ) )
-                != 0 )
+    if( ( ret = ecdh_compute_shared( &ctx->grp, &ctx->z, &ctx->Qp, &ctx->d,
+                                     f_rng, p_rng ) ) != 0 )
+    {
         return( ret );
+    }
 
     if( mpi_size( &ctx->z ) > blen )
         return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
diff --git a/library/ecdsa.c b/library/ecdsa.c
index 67774c9..bbdb5d5 100644
--- a/library/ecdsa.c
+++ b/library/ecdsa.c
@@ -161,9 +161,12 @@
 
     /*
      * Step 5: R = u1 G + u2 Q
+     *
+     * Since we're not using any secret data, no need to pass a RNG to
+     * ecp_mul() for countermesures.
      */
-    MPI_CHK( ecp_mul( grp, &R, &u1, &grp->G ) );
-    MPI_CHK( ecp_mul( grp, &P, &u2, Q ) );
+    MPI_CHK( ecp_mul( grp, &R, &u1, &grp->G, NULL, NULL ) );
+    MPI_CHK( ecp_mul( grp, &P, &u2, Q, NULL, NULL ) );
     MPI_CHK( ecp_add( grp, &R, &R, &P ) );
 
     if( ecp_is_zero( &R ) )
diff --git a/library/ecp.c b/library/ecp.c
index 09a021b..b4ee042 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -1166,7 +1166,8 @@
  * random m in the range 0 .. 2^nbits - 1.
  */
 int ecp_mul( const ecp_group *grp, ecp_point *R,
-             const mpi *m, const ecp_point *P )
+             const mpi *m, const ecp_point *P,
+             int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
 {
     int ret;
     unsigned char w, m_is_odd;
@@ -1175,18 +1176,21 @@
     ecp_point Q, T[ MAX_PRE_LEN ];
     mpi M;
 
+    ((void) f_rng);
+    ((void) p_rng);
+
     if( mpi_cmp_int( m, 0 ) < 0 || mpi_msb( m ) > grp->nbits )
-        return( POLARSSL_ERR_ECP_GENERIC );
+        return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
 
     w = grp->nbits >= 521 ? 6 :
         grp->nbits >= 224 ? 5 :
-        4;
+                            4;
 
     /*
      * Make sure w is within the limits.
      * The last test ensures that none of the precomputed points is zero,
      * which wouldn't be handled correctly by ecp_normalize_many().
-     * It is only useful for small curves, as used in the test suite.
+     * It is only useful for very small curves, as used in the test suite.
      */
     if( w > POLARSSL_ECP_WINDOW_SIZE )
         w = POLARSSL_ECP_WINDOW_SIZE;
@@ -1348,7 +1352,7 @@
     }
     while( mpi_cmp_int( d, 1 ) < 0 );
 
-    return( ecp_mul( grp, Q, d, &grp->G ) );
+    return( ecp_mul( grp, Q, d, &grp->G, f_rng, p_rng ) );
 }
 
 #if defined(POLARSSL_SELF_TEST)
@@ -1402,12 +1406,12 @@
 #endif /* POLARSSL_ECP_DP_SECP192R1_ENABLED */
 
     if( verbose != 0 )
-        printf( "  ECP test #1 (SPA resistance): " );
+        printf( "  ECP test #1 (resistance to simple timing attacks): " );
 
     add_count = 0;
     dbl_count = 0;
     MPI_CHK( mpi_read_string( &m, 16, exponents[0] ) );
-    MPI_CHK( ecp_mul( &grp, &R, &m, &grp.G ) );
+    MPI_CHK( ecp_mul( &grp, &R, &m, &grp.G, NULL, NULL ) );
 
     for( i = 1; i < sizeof( exponents ) / sizeof( exponents[0] ); i++ )
     {
@@ -1417,7 +1421,7 @@
         dbl_count = 0;
 
         MPI_CHK( mpi_read_string( &m, 16, exponents[i] ) );
-        MPI_CHK( ecp_mul( &grp, &R, &m, &grp.G ) );
+        MPI_CHK( ecp_mul( &grp, &R, &m, &grp.G, NULL, NULL ) );
 
         if( add_count != add_c_prev || dbl_count != dbl_c_prev )
         {
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 0fccf34..3b9d142 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -1748,7 +1748,8 @@
         if( ( ret = ecdh_calc_secret( &ssl->handshake->ecdh_ctx,
                                       &ssl->handshake->pmslen,
                                        ssl->handshake->premaster,
-                                       POLARSSL_MPI_MAX_SIZE ) ) != 0 )
+                                       POLARSSL_MPI_MAX_SIZE,
+                                       ssl->f_rng, ssl->p_rng ) ) != 0 )
         {
             SSL_DEBUG_RET( 1, "ecdh_calc_secret", ret );
             return( ret );
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 5bedcad..adf5a62 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -2410,7 +2410,8 @@
         if( ( ret = ecdh_calc_secret( &ssl->handshake->ecdh_ctx,
                                       &ssl->handshake->pmslen,
                                        ssl->handshake->premaster,
-                                       POLARSSL_MPI_MAX_SIZE ) ) != 0 )
+                                       POLARSSL_MPI_MAX_SIZE,
+                                       ssl->f_rng, ssl->p_rng ) ) != 0 )
         {
             SSL_DEBUG_RET( 1, "ecdh_calc_secret", ret );
             return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE_CS );