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diff --git a/grub-core/lib/libgcrypt/mpi/mpi-mod.c b/grub-core/lib/libgcrypt/mpi/mpi-mod.c
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+/* mpi-mod.c - Modular reduction
+ Copyright (C) 1998, 1999, 2001, 2002, 2003,
+ 2007 Free Software Foundation, Inc.
+
+ This file is part of Libgcrypt.
+
+ Libgcrypt is free software; you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of
+ the License, or (at your option) any later version.
+
+ Libgcrypt 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 Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+ USA. */
+
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "mpi-internal.h"
+#include "longlong.h"
+#include "g10lib.h"
+
+
+/* Context used with Barrett reduction. */
+struct barrett_ctx_s
+{
+ gcry_mpi_t m; /* The modulus - may not be modified. */
+ int m_copied; /* If true, M needs to be released. */
+ int k;
+ gcry_mpi_t y;
+ gcry_mpi_t r1; /* Helper MPI. */
+ gcry_mpi_t r2; /* Helper MPI. */
+ gcry_mpi_t r3; /* Helper MPI allocated on demand. */
+};
+
+
+
+void
+_gcry_mpi_mod (gcry_mpi_t rem, gcry_mpi_t dividend, gcry_mpi_t divisor)
+{
+ _gcry_mpi_fdiv_r (rem, dividend, divisor);
+ rem->sign = 0;
+}
+
+
+/* This function returns a new context for Barrett based operations on
+ the modulus M. This context needs to be released using
+ _gcry_mpi_barrett_free. If COPY is true M will be transferred to
+ the context and the user may change M. If COPY is false, M may not
+ be changed until gcry_mpi_barrett_free has been called. */
+mpi_barrett_t
+_gcry_mpi_barrett_init (gcry_mpi_t m, int copy)
+{
+ mpi_barrett_t ctx;
+ gcry_mpi_t tmp;
+
+ mpi_normalize (m);
+ ctx = gcry_xcalloc (1, sizeof *ctx);
+
+ if (copy)
+ {
+ ctx->m = mpi_copy (m);
+ ctx->m_copied = 1;
+ }
+ else
+ ctx->m = m;
+
+ ctx->k = mpi_get_nlimbs (m);
+ tmp = mpi_alloc (ctx->k + 1);
+
+ /* Barrett precalculation: y = floor(b^(2k) / m). */
+ mpi_set_ui (tmp, 1);
+ mpi_lshift_limbs (tmp, 2 * ctx->k);
+ mpi_fdiv_q (tmp, tmp, m);
+
+ ctx->y = tmp;
+ ctx->r1 = mpi_alloc ( 2 * ctx->k + 1 );
+ ctx->r2 = mpi_alloc ( 2 * ctx->k + 1 );
+
+ return ctx;
+}
+
+void
+_gcry_mpi_barrett_free (mpi_barrett_t ctx)
+{
+ if (ctx)
+ {
+ mpi_free (ctx->y);
+ mpi_free (ctx->r1);
+ mpi_free (ctx->r2);
+ if (ctx->r3)
+ mpi_free (ctx->r3);
+ if (ctx->m_copied)
+ mpi_free (ctx->m);
+ gcry_free (ctx);
+ }
+}
+
+
+/* R = X mod M
+
+ Using Barrett reduction. Before using this function
+ _gcry_mpi_barrett_init must have been called to do the
+ precalculations. CTX is the context created by this precalculation
+ and also conveys M. If the Barret reduction could no be done a
+ starightforward reduction method is used.
+
+ We assume that these conditions are met:
+ Input: x =(x_2k-1 ...x_0)_b
+ m =(m_k-1 ....m_0)_b with m_k-1 != 0
+ Output: r = x mod m
+ */
+void
+_gcry_mpi_mod_barrett (gcry_mpi_t r, gcry_mpi_t x, mpi_barrett_t ctx)
+{
+ gcry_mpi_t m = ctx->m;
+ int k = ctx->k;
+ gcry_mpi_t y = ctx->y;
+ gcry_mpi_t r1 = ctx->r1;
+ gcry_mpi_t r2 = ctx->r2;
+
+ mpi_normalize (x);
+ if (mpi_get_nlimbs (x) > 2*k )
+ {
+ mpi_mod (r, x, m);
+ return;
+ }
+
+ /* 1. q1 = floor( x / b^k-1)
+ * q2 = q1 * y
+ * q3 = floor( q2 / b^k+1 )
+ * Actually, we don't need qx, we can work direct on r2
+ */
+ mpi_set ( r2, x );
+ mpi_rshift_limbs ( r2, k-1 );
+ mpi_mul ( r2, r2, y );
+ mpi_rshift_limbs ( r2, k+1 );
+
+ /* 2. r1 = x mod b^k+1
+ * r2 = q3 * m mod b^k+1
+ * r = r1 - r2
+ * 3. if r < 0 then r = r + b^k+1
+ */
+ mpi_set ( r1, x );
+ if ( r1->nlimbs > k+1 ) /* Quick modulo operation. */
+ r1->nlimbs = k+1;
+ mpi_mul ( r2, r2, m );
+ if ( r2->nlimbs > k+1 ) /* Quick modulo operation. */
+ r2->nlimbs = k+1;
+ mpi_sub ( r, r1, r2 );
+
+ if ( mpi_is_neg( r ) )
+ {
+ if (!ctx->r3)
+ {
+ ctx->r3 = mpi_alloc ( k + 2 );
+ mpi_set_ui (ctx->r3, 1);
+ mpi_lshift_limbs (ctx->r3, k + 1 );
+ }
+ mpi_add ( r, r, ctx->r3 );
+ }
+
+ /* 4. while r >= m do r = r - m */
+ while ( mpi_cmp( r, m ) >= 0 )
+ mpi_sub ( r, r, m );
+
+}
+
+
+void
+_gcry_mpi_mul_barrett (gcry_mpi_t w, gcry_mpi_t u, gcry_mpi_t v,
+ mpi_barrett_t ctx)
+{
+ gcry_mpi_mul (w, u, v);
+ mpi_mod_barrett (w, w, ctx);
+}