1 files changed, 187 insertions, 0 deletions
diff --git a/lib/mpi/mpi-inv.c b/lib/mpi/mpi-inv.c
new file mode 100644
index 000000000000..0951f9847745
--- /dev/null
+++ b/lib/mpi/mpi-inv.c
@@ -0,0 +1,187 @@
+/* mpi-inv.c  -  MPI functions
+ * Copyright (C) 1998, 1999, 2000, 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
+ */
+#include "mpi-internal.h"
+/****************
+ * Calculate the multiplicative inverse X of A mod N
+ * That is: Find the solution x for
+ *              1 = (a*x) mod n
+ */
+int mpi_invm(MPI x, const MPI a, const MPI n)
+{
+        /* Extended Euclid's algorithm (See TAOPC Vol II, 4.5.2, Alg X)
+         * modified according to Michael Penk's solution for Exercice 35
+         * with further enhancement */
+        MPI u = NULL, v = NULL;
+        MPI u1 = NULL, u2 = NULL, u3 = NULL;
+        MPI v1 = NULL, v2 = NULL, v3 = NULL;
+        MPI t1 = NULL, t2 = NULL, t3 = NULL;
+        unsigned k;
+        int sign;
+        int odd = 0;
+        int rc = -ENOMEM;
+        if (mpi_copy(&u, a) < 0)
+                goto cleanup;
+        if (mpi_copy(&v, n) < 0)
+                goto cleanup;
+        for (k = 0; !mpi_test_bit(u, 0) && !mpi_test_bit(v, 0); k++) {
+                if (mpi_rshift(u, u, 1) < 0)
+                        goto cleanup;
+                if (mpi_rshift(v, v, 1) < 0)
+                        goto cleanup;
+        }
+        odd = mpi_test_bit(v, 0);
+        u1 = mpi_alloc_set_ui(1);
+        if (!u1)
+                goto cleanup;
+        if (!odd) {
+                u2 = mpi_alloc_set_ui(0);
+                if (!u2)
+                        goto cleanup;
+        }
+        if (mpi_copy(&u3, u) < 0)
+                goto cleanup;
+        if (mpi_copy(&v1, v) < 0)
+                goto cleanup;
+        if (!odd) {
+                v2 = mpi_alloc(mpi_get_nlimbs(u));
+                if (!v2)
+                        goto cleanup;
+                if (mpi_sub(v2, u1, u) < 0)
+                        goto cleanup;   /* U is used as const 1 */
+        }
+        if (mpi_copy(&v3, v) < 0)
+                goto cleanup;
+        if (mpi_test_bit(u, 0)) {       /* u is odd */
+                t1 = mpi_alloc_set_ui(0);
+                if (!t1)
+                        goto cleanup;
+                if (!odd) {
+                        t2 = mpi_alloc_set_ui(1);
+                        if (!t2)
+                                goto cleanup;
+                        t2->sign = 1;
+                }
+                if (mpi_copy(&t3, v) < 0)
+                        goto cleanup;
+                t3->sign = !t3->sign;
+                goto Y4;
+        } else {
+                t1 = mpi_alloc_set_ui(1);
+                if (!t1)
+                        goto cleanup;
+                if (!odd) {
+                        t2 = mpi_alloc_set_ui(0);
+                        if (!t2)
+                                goto cleanup;
+                }
+                if (mpi_copy(&t3, u) < 0)
+                        goto cleanup;
+        }
+        do {
+                do {
+                        if (!odd) {
+                                if (mpi_test_bit(t1, 0) || mpi_test_bit(t2, 0)) {       /* one is odd */
+                                        if (mpi_add(t1, t1, v) < 0)
+                                                goto cleanup;
+                                        if (mpi_sub(t2, t2, u) < 0)
+                                                goto cleanup;
+                                }
+                                if (mpi_rshift(t1, t1, 1) < 0)
+                                        goto cleanup;
+                                if (mpi_rshift(t2, t2, 1) < 0)
+                                        goto cleanup;
+                                if (mpi_rshift(t3, t3, 1) < 0)
+                                        goto cleanup;
+                        } else {
+                                if (mpi_test_bit(t1, 0))
+                                        if (mpi_add(t1, t1, v) < 0)
+                                                goto cleanup;
+                                if (mpi_rshift(t1, t1, 1) < 0)
+                                        goto cleanup;
+                                if (mpi_rshift(t3, t3, 1) < 0)
+                                        goto cleanup;
+                        }
+Y4:
+                        ;
+                } while (!mpi_test_bit(t3, 0)); /* while t3 is even */
+                if (!t3->sign) {
+                        if (mpi_set(u1, t1) < 0)
+                                goto cleanup;
+                        if (!odd)
+                                if (mpi_set(u2, t2) < 0)
+                                        goto cleanup;
+                        if (mpi_set(u3, t3) < 0)
+                                goto cleanup;
+                } else {
+                        if (mpi_sub(v1, v, t1) < 0)
+                                goto cleanup;
+                        sign = u->sign;
+                        u->sign = !u->sign;
+                        if (!odd)
+                                if (mpi_sub(v2, u, t2) < 0)
+                                        goto cleanup;
+                        u->sign = sign;
+                        sign = t3->sign;
+                        t3->sign = !t3->sign;
+                        if (mpi_set(v3, t3) < 0)
+                                goto cleanup;
+                        t3->sign = sign;
+                }
+                if (mpi_sub(t1, u1, v1) < 0)
+                        goto cleanup;
+                if (!odd)
+                        if (mpi_sub(t2, u2, v2) < 0)
+                                goto cleanup;
+                if (mpi_sub(t3, u3, v3) < 0)
+                        goto cleanup;
+                if (t1->sign) {
+                        if (mpi_add(t1, t1, v) < 0)
+                                goto cleanup;
+                        if (!odd)
+                                if (mpi_sub(t2, t2, u) < 0)
+                                        goto cleanup;
+                }
+        } while (mpi_cmp_ui(t3, 0));    /* while t3 != 0 */
+        /* mpi_lshift( u3, k ); */
+        rc = mpi_set(x, u1);
+cleanup:
+        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);
+        return rc;
+}

diff --git a/lib/mpi/mpi-inv.c b/lib/mpi/mpi-inv.c new file mode 100644 index 000000000000..0951f9847745 --- /dev/null +++ b/lib/mpi/mpi-inv.c
@@ -0,0 +1,187 @@
	1	/* mpi-inv.c - MPI functions
	2	* Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
	3	*
	4	* This file is part of GnuPG.
	5	*
	6	* GnuPG is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License as published by
	8	* the Free Software Foundation; either version 2 of the License, or
	9	* (at your option) any later version.
	10	*
	11	* GnuPG is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program; if not, write to the Free Software
	18	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
	19	*/
	20
	21	#include "mpi-internal.h"
	22
	23	/****************
	24	* Calculate the multiplicative inverse X of A mod N
	25	* That is: Find the solution x for
	26	* 1 = (a*x) mod n
	27	*/
	28	int mpi_invm(MPI x, const MPI a, const MPI n)
	29	{
	30	/* Extended Euclid's algorithm (See TAOPC Vol II, 4.5.2, Alg X)
	31	* modified according to Michael Penk's solution for Exercice 35
	32	* with further enhancement */
	33	MPI u = NULL, v = NULL;
	34	MPI u1 = NULL, u2 = NULL, u3 = NULL;
	35	MPI v1 = NULL, v2 = NULL, v3 = NULL;
	36	MPI t1 = NULL, t2 = NULL, t3 = NULL;
	37	unsigned k;
	38	int sign;
	39	int odd = 0;
	40	int rc = -ENOMEM;
	41
	42	if (mpi_copy(&u, a) < 0)
	43	goto cleanup;
	44	if (mpi_copy(&v, n) < 0)
	45	goto cleanup;
	46
	47	for (k = 0; !mpi_test_bit(u, 0) && !mpi_test_bit(v, 0); k++) {
	48	if (mpi_rshift(u, u, 1) < 0)
	49	goto cleanup;
	50	if (mpi_rshift(v, v, 1) < 0)
	51	goto cleanup;
	52	}
	53	odd = mpi_test_bit(v, 0);
	54
	55	u1 = mpi_alloc_set_ui(1);
	56	if (!u1)
	57	goto cleanup;
	58	if (!odd) {
	59	u2 = mpi_alloc_set_ui(0);
	60	if (!u2)
	61	goto cleanup;
	62	}
	63	if (mpi_copy(&u3, u) < 0)
	64	goto cleanup;
	65	if (mpi_copy(&v1, v) < 0)
	66	goto cleanup;
	67	if (!odd) {
	68	v2 = mpi_alloc(mpi_get_nlimbs(u));
	69	if (!v2)
	70	goto cleanup;
	71	if (mpi_sub(v2, u1, u) < 0)
	72	goto cleanup; /* U is used as const 1 */
	73	}
	74	if (mpi_copy(&v3, v) < 0)
	75	goto cleanup;
	76	if (mpi_test_bit(u, 0)) { /* u is odd */
	77	t1 = mpi_alloc_set_ui(0);
	78	if (!t1)
	79	goto cleanup;
	80	if (!odd) {
	81	t2 = mpi_alloc_set_ui(1);
	82	if (!t2)
	83	goto cleanup;
	84	t2->sign = 1;
	85	}
	86	if (mpi_copy(&t3, v) < 0)
	87	goto cleanup;
	88	t3->sign = !t3->sign;
	89	goto Y4;
	90	} else {
	91	t1 = mpi_alloc_set_ui(1);
	92	if (!t1)
	93	goto cleanup;
	94	if (!odd) {
	95	t2 = mpi_alloc_set_ui(0);
	96	if (!t2)
	97	goto cleanup;
	98	}
	99	if (mpi_copy(&t3, u) < 0)
	100	goto cleanup;
	101	}
	102	do {
	103	do {
	104	if (!odd) {
	105	if (mpi_test_bit(t1, 0) \|\| mpi_test_bit(t2, 0)) { /* one is odd */
	106	if (mpi_add(t1, t1, v) < 0)
	107	goto cleanup;
	108	if (mpi_sub(t2, t2, u) < 0)
	109	goto cleanup;
	110	}
	111	if (mpi_rshift(t1, t1, 1) < 0)
	112	goto cleanup;
	113	if (mpi_rshift(t2, t2, 1) < 0)
	114	goto cleanup;
	115	if (mpi_rshift(t3, t3, 1) < 0)
	116	goto cleanup;
	117	} else {
	118	if (mpi_test_bit(t1, 0))
	119	if (mpi_add(t1, t1, v) < 0)
	120	goto cleanup;
	121	if (mpi_rshift(t1, t1, 1) < 0)
	122	goto cleanup;
	123	if (mpi_rshift(t3, t3, 1) < 0)
	124	goto cleanup;
	125	}
	126	Y4:
	127	;
	128	} while (!mpi_test_bit(t3, 0)); /* while t3 is even */
	129
	130	if (!t3->sign) {
	131	if (mpi_set(u1, t1) < 0)
	132	goto cleanup;
	133	if (!odd)
	134	if (mpi_set(u2, t2) < 0)
	135	goto cleanup;
	136	if (mpi_set(u3, t3) < 0)
	137	goto cleanup;
	138	} else {
	139	if (mpi_sub(v1, v, t1) < 0)
	140	goto cleanup;
	141	sign = u->sign;
	142	u->sign = !u->sign;
	143	if (!odd)
	144	if (mpi_sub(v2, u, t2) < 0)
	145	goto cleanup;
	146	u->sign = sign;
	147	sign = t3->sign;
	148	t3->sign = !t3->sign;
	149	if (mpi_set(v3, t3) < 0)
	150	goto cleanup;
	151	t3->sign = sign;
	152	}
	153	if (mpi_sub(t1, u1, v1) < 0)
	154	goto cleanup;
	155	if (!odd)
	156	if (mpi_sub(t2, u2, v2) < 0)
	157	goto cleanup;
	158	if (mpi_sub(t3, u3, v3) < 0)
	159	goto cleanup;
	160	if (t1->sign) {
	161	if (mpi_add(t1, t1, v) < 0)
	162	goto cleanup;
	163	if (!odd)
	164	if (mpi_sub(t2, t2, u) < 0)
	165	goto cleanup;
	166	}
	167	} while (mpi_cmp_ui(t3, 0)); /* while t3 != 0 */
	168	/* mpi_lshift( u3, k ); */
	169	rc = mpi_set(x, u1);
	170
	171	cleanup:
	172	mpi_free(u1);
	173	mpi_free(v1);
	174	mpi_free(t1);
	175	if (!odd) {
	176	mpi_free(u2);
	177	mpi_free(v2);
	178	mpi_free(t2);
	179	}
	180	mpi_free(u3);
	181	mpi_free(v3);
	182	mpi_free(t3);
	183
	184	mpi_free(u);
	185	mpi_free(v);
	186	return rc;
	187	}