From 485f6ecd453d8a2fd8b9b9fadea03159d8b50797 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Sat, 27 Apr 2024 12:54:16 +0200
Subject: Adding upstream version 2.06.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 grub-core/lib/libgcrypt/mpi/mpi-mpow.c | 223 +++++++++++++++++++++++++++++++++
 1 file changed, 223 insertions(+)
 create mode 100644 grub-core/lib/libgcrypt/mpi/mpi-mpow.c

(limited to 'grub-core/lib/libgcrypt/mpi/mpi-mpow.c')

diff --git a/grub-core/lib/libgcrypt/mpi/mpi-mpow.c b/grub-core/lib/libgcrypt/mpi/mpi-mpow.c
new file mode 100644
index 0000000..ca5b3f1
--- /dev/null
+++ b/grub-core/lib/libgcrypt/mpi/mpi-mpow.c
@@ -0,0 +1,223 @@
+/* mpi-mpow.c  -  MPI functions
+ *	Copyright (C) 1998, 1999, 2001, 2002, 2003 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "mpi-internal.h"
+#include "longlong.h"
+#include "g10lib.h"
+
+
+/* Barrett is slower than the classical way.  It can be tweaked by
+ * using partial multiplications
+ */
+/*#define USE_BARRETT*/
+
+
+
+#ifdef USE_BARRETT
+static void barrett_mulm( gcry_mpi_t w, gcry_mpi_t u, gcry_mpi_t v, gcry_mpi_t m, gcry_mpi_t y, int k, gcry_mpi_t r1, gcry_mpi_t r2 );
+static gcry_mpi_t init_barrett( gcry_mpi_t m, int *k, gcry_mpi_t *r1, gcry_mpi_t *r2 );
+static int calc_barrett( gcry_mpi_t r, gcry_mpi_t x, gcry_mpi_t m, gcry_mpi_t y, int k, gcry_mpi_t r1, gcry_mpi_t r2  );
+#else
+#define barrett_mulm( w, u, v, m, y, k, r1, r2 ) gcry_mpi_mulm( (w), (u), (v), (m) )
+#endif
+
+
+static int
+build_index( gcry_mpi_t *exparray, int k, int i, int t )
+{
+    int j, bitno;
+    int idx = 0;
+
+    bitno = t-i;
+    for(j=k-1; j >= 0; j-- ) {
+	idx <<= 1;
+	if( mpi_test_bit( exparray[j], bitno ) )
+	    idx |= 1;
+    }
+    /*log_debug("t=%d i=%d idx=%d\n", t, i, idx );*/
+    return idx;
+}
+
+/****************
+ * RES = (BASE[0] ^ EXP[0]) *  (BASE[1] ^ EXP[1]) * ... * mod M
+ */
+void
+_gcry_mpi_mulpowm( gcry_mpi_t res, gcry_mpi_t *basearray, gcry_mpi_t *exparray, gcry_mpi_t m)
+{
+    int k;	/* number of elements */
+    int t;	/* bit size of largest exponent */
+    int i, j, idx;
+    gcry_mpi_t *G;	/* table with precomputed values of size 2^k */
+    gcry_mpi_t tmp;
+#ifdef USE_BARRETT
+    gcry_mpi_t barrett_y, barrett_r1, barrett_r2;
+    int barrett_k;
+#endif
+
+    for(k=0; basearray[k]; k++ )
+	;
+    gcry_assert(k);
+    for(t=0, i=0; (tmp=exparray[i]); i++ ) {
+	/*log_mpidump("exp: ", tmp );*/
+	j = mpi_get_nbits(tmp);
+	if( j > t )
+	    t = j;
+    }
+    /*log_mpidump("mod: ", m );*/
+    gcry_assert (i==k);
+    gcry_assert (t);
+    gcry_assert (k < 10);
+
+    G = gcry_xcalloc( (1<<k) , sizeof *G );
+#ifdef USE_BARRETT
+    barrett_y = init_barrett( m, &barrett_k, &barrett_r1, &barrett_r2 );
+#endif
+    /* and calculate */
+    tmp =  mpi_alloc( mpi_get_nlimbs(m)+1 );
+    mpi_set_ui( res, 1 );
+    for(i = 1; i <= t; i++ ) {
+	barrett_mulm(tmp, res, res, m, barrett_y, barrett_k,
+				       barrett_r1, barrett_r2 );
+	idx = build_index( exparray, k, i, t );
+	gcry_assert (idx >= 0 && idx < (1<<k));
+	if( !G[idx] ) {
+	    if( !idx )
+		 G[0] = mpi_alloc_set_ui( 1 );
+	    else {
+		for(j=0; j < k; j++ ) {
+		    if( (idx & (1<<j) ) ) {
+			if( !G[idx] )
+			    G[idx] = mpi_copy( basearray[j] );
+			else
+			    barrett_mulm( G[idx], G[idx], basearray[j],
+					       m, barrett_y, barrett_k, barrett_r1, barrett_r2	);
+		    }
+		}
+		if( !G[idx] )
+		    G[idx] = mpi_alloc(0);
+	    }
+	}
+	barrett_mulm(res, tmp, G[idx], m, barrett_y, barrett_k, barrett_r1, barrett_r2	);
+    }
+
+    /* cleanup */
+    mpi_free(tmp);
+#ifdef USE_BARRETT
+    mpi_free(barrett_y);
+    mpi_free(barrett_r1);
+    mpi_free(barrett_r2);
+#endif
+    for(i=0; i < (1<<k); i++ )
+	mpi_free(G[i]);
+    gcry_free(G);
+}
+
+
+
+#ifdef USE_BARRETT
+static void
+barrett_mulm( gcry_mpi_t w, gcry_mpi_t u, gcry_mpi_t v, gcry_mpi_t m, gcry_mpi_t y, int k, gcry_mpi_t r1, gcry_mpi_t r2	)
+{
+    mpi_mul(w, u, v);
+    if( calc_barrett( w, w, m, y, k, r1, r2 ) )
+	mpi_fdiv_r( w, w, m );
+}
+
+/****************
+ * Barrett precalculation: y = floor(b^(2k) / m)
+ */
+static gcry_mpi_t
+init_barrett( gcry_mpi_t m, int *k, gcry_mpi_t *r1, gcry_mpi_t *r2 )
+{
+    gcry_mpi_t tmp;
+
+    mpi_normalize( m );
+    *k = mpi_get_nlimbs( m );
+    tmp = mpi_alloc( *k + 1 );
+    mpi_set_ui( tmp, 1 );
+    mpi_lshift_limbs( tmp, 2 * *k );
+    mpi_fdiv_q( tmp, tmp, m );
+    *r1 = mpi_alloc( 2* *k + 1 );
+    *r2 = mpi_alloc( 2* *k + 1 );
+    return tmp;
+}
+
+/****************
+ * Barrett reduction: We assume that these conditions are met:
+ * Given x =(x_2k-1 ...x_0)_b
+ *	 m =(m_k-1 ....m_0)_b	  with m_k-1 != 0
+ * Output r = x mod m
+ * Before using this function init_barret must be used to calucalte y and k.
+ * Returns: false = no error
+ *	    true = can't perform barret reduction
+ */
+static int
+calc_barrett( gcry_mpi_t r, gcry_mpi_t x, gcry_mpi_t m, gcry_mpi_t y, int k, gcry_mpi_t r1, gcry_mpi_t r2 )
+{
+    int xx = k > 3 ? k-3:0;
+
+    mpi_normalize( x );
+    if( mpi_get_nlimbs(x) > 2*k )
+	return 1; /* can't do it */
+
+    /* 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 ) ) {
+	gcry_mpi_t tmp;
+
+	tmp = mpi_alloc( k + 2 );
+	mpi_set_ui( tmp, 1 );
+	mpi_lshift_limbs( tmp, k+1 );
+	mpi_add( r, r, tmp );
+	mpi_free(tmp);
+    }
+
+    /* 4. while r >= m do r = r - m */
+    while( mpi_cmp( r, m ) >= 0 )
+	mpi_sub( r, r, m );
+
+    return 0;
+}
+#endif /* USE_BARRETT */
-- 
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