summaryrefslogtreecommitdiff
path: root/plugins/MirOTR/Libgcrypt/mpi/mpi-inv.c
diff options
context:
space:
mode:
Diffstat (limited to 'plugins/MirOTR/Libgcrypt/mpi/mpi-inv.c')
-rw-r--r--plugins/MirOTR/Libgcrypt/mpi/mpi-inv.c267
1 files changed, 267 insertions, 0 deletions
diff --git a/plugins/MirOTR/Libgcrypt/mpi/mpi-inv.c b/plugins/MirOTR/Libgcrypt/mpi/mpi-inv.c
new file mode 100644
index 0000000000..5d269466e0
--- /dev/null
+++ b/plugins/MirOTR/Libgcrypt/mpi/mpi-inv.c
@@ -0,0 +1,267 @@
+/* mpi-inv.c - MPI functions
+ * Copyright (C) 1998, 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "mpi-internal.h"
+#include "g10lib.h"
+
+/****************
+ * Calculate the multiplicative inverse X of A mod N
+ * That is: Find the solution x for
+ * 1 = (a*x) mod n
+ */
+int
+gcry_mpi_invm( gcry_mpi_t x, gcry_mpi_t a, gcry_mpi_t n )
+{
+#if 0
+ gcry_mpi_t u, v, u1, u2, u3, v1, v2, v3, q, t1, t2, t3;
+ gcry_mpi_t ta, tb, tc;
+
+ u = mpi_copy(a);
+ v = mpi_copy(n);
+ u1 = mpi_alloc_set_ui(1);
+ u2 = mpi_alloc_set_ui(0);
+ u3 = mpi_copy(u);
+ v1 = mpi_alloc_set_ui(0);
+ v2 = mpi_alloc_set_ui(1);
+ v3 = mpi_copy(v);
+ q = mpi_alloc( mpi_get_nlimbs(u)+1 );
+ t1 = mpi_alloc( mpi_get_nlimbs(u)+1 );
+ t2 = mpi_alloc( mpi_get_nlimbs(u)+1 );
+ t3 = mpi_alloc( mpi_get_nlimbs(u)+1 );
+ while( mpi_cmp_ui( v3, 0 ) ) {
+ mpi_fdiv_q( q, u3, v3 );
+ mpi_mul(t1, v1, q); mpi_mul(t2, v2, q); mpi_mul(t3, v3, q);
+ mpi_sub(t1, u1, t1); mpi_sub(t2, u2, t2); mpi_sub(t3, u3, t3);
+ mpi_set(u1, v1); mpi_set(u2, v2); mpi_set(u3, v3);
+ mpi_set(v1, t1); mpi_set(v2, t2); mpi_set(v3, t3);
+ }
+ /* log_debug("result:\n");
+ log_mpidump("q =", q );
+ log_mpidump("u1=", u1);
+ log_mpidump("u2=", u2);
+ log_mpidump("u3=", u3);
+ log_mpidump("v1=", v1);
+ log_mpidump("v2=", v2); */
+ mpi_set(x, u1);
+
+ mpi_free(u1);
+ mpi_free(u2);
+ mpi_free(u3);
+ mpi_free(v1);
+ mpi_free(v2);
+ mpi_free(v3);
+ mpi_free(q);
+ mpi_free(t1);
+ mpi_free(t2);
+ mpi_free(t3);
+ mpi_free(u);
+ mpi_free(v);
+#elif 0
+ /* Extended Euclid's algorithm (See TAOCP Vol II, 4.5.2, Alg X)
+ * modified according to Michael Penk's solution for Exercise 35 */
+
+ /* FIXME: we can simplify this in most cases (see Knuth) */
+ gcry_mpi_t u, v, u1, u2, u3, v1, v2, v3, t1, t2, t3;
+ unsigned k;
+ int sign;
+
+ u = mpi_copy(a);
+ v = mpi_copy(n);
+ for(k=0; !mpi_test_bit(u,0) && !mpi_test_bit(v,0); k++ ) {
+ mpi_rshift(u, u, 1);
+ mpi_rshift(v, v, 1);
+ }
+
+
+ u1 = mpi_alloc_set_ui(1);
+ u2 = mpi_alloc_set_ui(0);
+ u3 = mpi_copy(u);
+ v1 = mpi_copy(v); /* !-- used as const 1 */
+ v2 = mpi_alloc( mpi_get_nlimbs(u) ); mpi_sub( v2, u1, u );
+ v3 = mpi_copy(v);
+ if( mpi_test_bit(u, 0) ) { /* u is odd */
+ t1 = mpi_alloc_set_ui(0);
+ t2 = mpi_alloc_set_ui(1); t2->sign = 1;
+ t3 = mpi_copy(v); t3->sign = !t3->sign;
+ goto Y4;
+ }
+ else {
+ t1 = mpi_alloc_set_ui(1);
+ t2 = mpi_alloc_set_ui(0);
+ t3 = mpi_copy(u);
+ }
+ do {
+ do {
+ if( mpi_test_bit(t1, 0) || mpi_test_bit(t2, 0) ) { /* one is odd */
+ mpi_add(t1, t1, v);
+ mpi_sub(t2, t2, u);
+ }
+ mpi_rshift(t1, t1, 1);
+ mpi_rshift(t2, t2, 1);
+ mpi_rshift(t3, t3, 1);
+ Y4:
+ ;
+ } while( !mpi_test_bit( t3, 0 ) ); /* while t3 is even */
+
+ if( !t3->sign ) {
+ mpi_set(u1, t1);
+ mpi_set(u2, t2);
+ mpi_set(u3, t3);
+ }
+ else {
+ mpi_sub(v1, v, t1);
+ sign = u->sign; u->sign = !u->sign;
+ mpi_sub(v2, u, t2);
+ u->sign = sign;
+ sign = t3->sign; t3->sign = !t3->sign;
+ mpi_set(v3, t3);
+ t3->sign = sign;
+ }
+ mpi_sub(t1, u1, v1);
+ mpi_sub(t2, u2, v2);
+ mpi_sub(t3, u3, v3);
+ if( t1->sign ) {
+ mpi_add(t1, t1, v);
+ mpi_sub(t2, t2, u);
+ }
+ } while( mpi_cmp_ui( t3, 0 ) ); /* while t3 != 0 */
+ /* mpi_lshift( u3, k ); */
+ mpi_set(x, u1);
+
+ mpi_free(u1);
+ mpi_free(u2);
+ mpi_free(u3);
+ mpi_free(v1);
+ mpi_free(v2);
+ mpi_free(v3);
+ mpi_free(t1);
+ mpi_free(t2);
+ mpi_free(t3);
+#else
+ /* Extended Euclid's algorithm (See TAOCP Vol II, 4.5.2, Alg X)
+ * modified according to Michael Penk's solution for Exercise 35
+ * with further enhancement */
+ gcry_mpi_t u, v, u1, u2=NULL, u3, v1, v2=NULL, v3, t1, t2=NULL, t3;
+ unsigned k;
+ int sign;
+ int odd ;
+
+ u = mpi_copy(a);
+ v = mpi_copy(n);
+
+ for(k=0; !mpi_test_bit(u,0) && !mpi_test_bit(v,0); k++ ) {
+ mpi_rshift(u, u, 1);
+ mpi_rshift(v, v, 1);
+ }
+ odd = mpi_test_bit(v,0);
+
+ u1 = mpi_alloc_set_ui(1);
+ if( !odd )
+ u2 = mpi_alloc_set_ui(0);
+ u3 = mpi_copy(u);
+ v1 = mpi_copy(v);
+ if( !odd ) {
+ v2 = mpi_alloc( mpi_get_nlimbs(u) );
+ mpi_sub( v2, u1, u ); /* U is used as const 1 */
+ }
+ v3 = mpi_copy(v);
+ if( mpi_test_bit(u, 0) ) { /* u is odd */
+ t1 = mpi_alloc_set_ui(0);
+ if( !odd ) {
+ t2 = mpi_alloc_set_ui(1); t2->sign = 1;
+ }
+ t3 = mpi_copy(v); t3->sign = !t3->sign;
+ goto Y4;
+ }
+ else {
+ t1 = mpi_alloc_set_ui(1);
+ if( !odd )
+ t2 = mpi_alloc_set_ui(0);
+ t3 = mpi_copy(u);
+ }
+ do {
+ do {
+ if( !odd ) {
+ if( mpi_test_bit(t1, 0) || mpi_test_bit(t2, 0) ) { /* one is odd */
+ mpi_add(t1, t1, v);
+ mpi_sub(t2, t2, u);
+ }
+ mpi_rshift(t1, t1, 1);
+ mpi_rshift(t2, t2, 1);
+ mpi_rshift(t3, t3, 1);
+ }
+ else {
+ if( mpi_test_bit(t1, 0) )
+ mpi_add(t1, t1, v);
+ mpi_rshift(t1, t1, 1);
+ mpi_rshift(t3, t3, 1);
+ }
+ Y4:
+ ;
+ } while( !mpi_test_bit( t3, 0 ) ); /* while t3 is even */
+
+ if( !t3->sign ) {
+ mpi_set(u1, t1);
+ if( !odd )
+ mpi_set(u2, t2);
+ mpi_set(u3, t3);
+ }
+ else {
+ mpi_sub(v1, v, t1);
+ sign = u->sign; u->sign = !u->sign;
+ if( !odd )
+ mpi_sub(v2, u, t2);
+ u->sign = sign;
+ sign = t3->sign; t3->sign = !t3->sign;
+ mpi_set(v3, t3);
+ t3->sign = sign;
+ }
+ mpi_sub(t1, u1, v1);
+ if( !odd )
+ mpi_sub(t2, u2, v2);
+ mpi_sub(t3, u3, v3);
+ if( t1->sign ) {
+ mpi_add(t1, t1, v);
+ if( !odd )
+ mpi_sub(t2, t2, u);
+ }
+ } while( mpi_cmp_ui( t3, 0 ) ); /* while t3 != 0 */
+ /* mpi_lshift( u3, k ); */
+ mpi_set(x, u1);
+
+ mpi_free(u1);
+ mpi_free(v1);
+ mpi_free(t1);
+ if( !odd ) {
+ mpi_free(u2);
+ mpi_free(v2);
+ mpi_free(t2);
+ }
+ mpi_free(u3);
+ mpi_free(v3);
+ mpi_free(t3);
+
+ mpi_free(u);
+ mpi_free(v);
+#endif
+ return 1;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-16 02:49:30 +0000