1 files changed, 91 insertions, 0 deletions
diff --git a/lib/mpi/mpi-mul.c b/lib/mpi/mpi-mul.c
new file mode 100644
index 000000000000..8f5fa200f297
--- /dev/null
+++ b/lib/mpi/mpi-mul.c
@@ -0,0 +1,91 @@
+/* mpi-mul.c  -  MPI functions
+ * Copyright (C) 1994, 1996, 1998, 2001, 2002,
+ *               2003 Free Software Foundation, Inc.
+ *
+ * This file is part of Libgcrypt.
+ *
+ * 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.
+ */
+
+#include "mpi-internal.h"
+
+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, 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;
+		up    = v->d;
+		vsize = u->nlimbs;
+		vsign = u->sign;
+		vp    = u->d;
+	} else {
+		usize = u->nlimbs;
+		usign = u->sign;
+		up    = u->d;
+		vsize = v->nlimbs;
+		vsign = v->sign;
+		vp    = v->d;
+	}
+	sign_product = usign ^ vsign;
+	wp = w->d;
+
+	/* Ensure W has space enough to store the result.  */
+	wsize = usize + vsize;
+	if (w->alloced < wsize) {
+		if (wp == up || wp == vp) {
+			wp = mpi_alloc_limb_space(wsize);
+			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);
+			/* 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);
+			/* Copy to the temporary space.  */
+			MPN_COPY(vp, wp, vsize);
+		}
+	}
+
+	if (!vsize)
+		wsize = 0;
+	else {
+		mpihelp_mul(wp, up, usize, vp, vsize, &cy);
+		wsize -= cy ? 0:1;
+	}
+
+	if (assign_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_tdiv_r(w, w, m);
+}
+EXPORT_SYMBOL_GPL(mpi_mulm);