Update head to match stable 1.0

mpi/mpi-mul.c

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+/* mpi-mul.c  -  MPI functions
+ *	Copyright (C) 1994, 1996 Free Software Foundation, Inc.
+ *	Copyright (C) 1998, 2001 Free Software Foundation, Inc.
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ *
+ * Note: This code is heavily based on the GNU MP Library.
+ *	 Actually it's the same code with only minor changes in the
+ *	 way the data is stored; this is to support the abstraction
+ *	 of an optional secure memory allocation which may be used
+ *	 to avoid revealing of sensitive data due to paging etc.
+ *	 The GNU MP Library itself is published under the LGPL;
+ *	 however I decided to publish this code under the plain GPL.
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "mpi-internal.h"
+
+
+void
+mpi_mul_ui( MPI prod, MPI mult, unsigned long small_mult )
+{
+    mpi_size_t size, prod_size;
+    mpi_ptr_t  prod_ptr;
+    mpi_limb_t cy;
+    int sign;
+
+    size = mult->nlimbs;
+    sign = mult->sign;
+
+    if( !size || !small_mult ) {
+	prod->nlimbs = 0;
+	prod->sign = 0;
+	return;
+    }
+
+    prod_size = size + 1;
+    if( prod->alloced < prod_size )
+	mpi_resize( prod, prod_size );
+    prod_ptr = prod->d;
+
+    cy = mpihelp_mul_1( prod_ptr, mult->d, size, (mpi_limb_t)small_mult );
+    if( cy )
+	prod_ptr[size++] = cy;
+    prod->nlimbs = size;
+    prod->sign = sign;
+}
+
+
+void
+mpi_mul_2exp( MPI w, MPI u, unsigned long cnt)
+{
+    mpi_size_t usize, wsize, limb_cnt;
+    mpi_ptr_t wp;
+    mpi_limb_t wlimb;
+    int usign, wsign;
+
+    usize = u->nlimbs;
+    usign = u->sign;
+
+    if( !usize ) {
+	w->nlimbs = 0;
+	w->sign = 0;
+	return;
+    }
+
+    limb_cnt = cnt / BITS_PER_MPI_LIMB;
+    wsize = usize + limb_cnt + 1;
+    if( w->alloced < wsize )
+	mpi_resize(w, wsize );
+    wp = w->d;
+    wsize = usize + limb_cnt;
+    wsign = usign;
+
+    cnt %= BITS_PER_MPI_LIMB;
+    if( cnt ) {
+	wlimb = mpihelp_lshift( wp + limb_cnt, u->d, usize, cnt );
+	if( wlimb ) {
+	    wp[wsize] = wlimb;
+	    wsize++;
+	}
+    }
+    else {
+	MPN_COPY_DECR( wp + limb_cnt, u->d, usize );
+    }
+
+    /* Zero all whole limbs at low end.  Do it here and not before calling
+     * mpn_lshift, not to lose for U == W.  */
+    MPN_ZERO( wp, limb_cnt );
+
+    w->nlimbs = wsize;
+    w->sign = wsign;
+}
+
+
+
+void
+mpi_mul( MPI w, MPI u, MPI v)
+{
+    mpi_size_t usize, vsize, wsize;
+    mpi_ptr_t up, vp, wp;
+    mpi_limb_t cy;
+    int usign, vsign, usecure, vsecure, sign_product;
+    int assign_wp=0;
+    mpi_ptr_t tmp_limb=NULL;
+
+
+    if( u->nlimbs < v->nlimbs ) { /* Swap U and V. */
+	usize = v->nlimbs;
+	usign = v->sign;
+	usecure = mpi_is_secure(v);
+	up    = v->d;
+	vsize = u->nlimbs;
+	vsign = u->sign;
+	vsecure = mpi_is_secure(u);
+	vp    = u->d;
+    }
+    else {
+	usize = u->nlimbs;
+	usign = u->sign;
+	usecure = mpi_is_secure(u);
+	up    = u->d;
+	vsize = v->nlimbs;
+	vsign = v->sign;
+	vsecure = mpi_is_secure(v);
+	vp    = v->d;
+    }
+    sign_product = usign ^ vsign;
+    wp = w->d;
+
+    /* Ensure W has space enough to store the result.  */
+    wsize = usize + vsize;
+    if ( !mpi_is_secure (w) && (mpi_is_secure (u) || mpi_is_secure (v)) ) {
+        /* w is not allocated in secure space but u or v is.  To make sure
+         * that no temporray results are stored in w, we temporary use 
+         * a newly allocated limb space for w */
+        wp = mpi_alloc_limb_space( wsize, 1 );
+        assign_wp = 2; /* mark it as 2 so that we can later copy it back to
+                        * mormal memory */
+    }
+    else if( w->alloced < wsize ) {
+	if( wp == up || wp == vp ) {
+	    wp = mpi_alloc_limb_space( wsize, mpi_is_secure(w) );
+	    assign_wp = 1;
+	}
+	else {
+	    mpi_resize(w, wsize );
+	    wp = w->d;
+	}
+    }
+    else { /* Make U and V not overlap with W.	*/
+	if( wp == up ) {
+	    /* W and U are identical.  Allocate temporary space for U.	*/
+	    up = tmp_limb = mpi_alloc_limb_space( usize, usecure  );
+	    /* Is V identical too?  Keep it identical with U.  */
+	    if( wp == vp )
+		vp = up;
+	    /* Copy to the temporary space.  */
+	    MPN_COPY( up, wp, usize );
+	}
+	else if( wp == vp ) {
+	    /* W and V are identical.  Allocate temporary space for V.	*/
+	    vp = tmp_limb = mpi_alloc_limb_space( vsize, vsecure );
+	    /* Copy to the temporary space.  */
+	    MPN_COPY( vp, wp, vsize );
+	}
+    }
+
+    if( !vsize )
+	wsize = 0;
+    else {
+	cy = mpihelp_mul( wp, up, usize, vp, vsize );
+	wsize -= cy? 0:1;
+    }
+
+    if( assign_wp ) {
+        if (assign_wp == 2) {
+            /* copy the temp wp from secure memory back to normal memory */
+	    mpi_ptr_t tmp_wp = mpi_alloc_limb_space (wsize, 0);
+	    MPN_COPY (tmp_wp, wp, wsize);
+            mpi_free_limb_space (wp);
+            wp = tmp_wp;
+        }
+	mpi_assign_limb_space( w, wp, wsize );
+    }
+    w->nlimbs = wsize;
+    w->sign = sign_product;
+    if( tmp_limb )
+	mpi_free_limb_space( tmp_limb );
+}
+
+
+void
+mpi_mulm( MPI w, MPI u, MPI v, MPI m)
+{
+    mpi_mul(w, u, v);
+    mpi_fdiv_r( w, w, m );
+}
+