1/* crypto/ec/ec2_smpt.c */
2/* This code was originally written by Douglas Stebila
3 * <dstebila@student.math.uwaterloo.ca> for the OpenSSL project.
4 */
5/* ====================================================================
6 * Copyright (c) 1998-2002 The OpenSSL Project.  All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in
17 *    the documentation and/or other materials provided with the
18 *    distribution.
19 *
20 * 3. All advertising materials mentioning features or use of this
21 *    software must display the following acknowledgment:
22 *    "This product includes software developed by the OpenSSL Project
23 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
24 *
25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26 *    endorse or promote products derived from this software without
27 *    prior written permission. For written permission, please contact
28 *    openssl-core@openssl.org.
29 *
30 * 5. Products derived from this software may not be called "OpenSSL"
31 *    nor may "OpenSSL" appear in their names without prior written
32 *    permission of the OpenSSL Project.
33 *
34 * 6. Redistributions of any form whatsoever must retain the following
35 *    acknowledgment:
36 *    "This product includes software developed by the OpenSSL Project
37 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
38 *
39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50 * OF THE POSSIBILITY OF SUCH DAMAGE.
51 * ====================================================================
52 *
53 * This product includes cryptographic software written by Eric Young
54 * (eay@cryptsoft.com).  This product includes software written by Tim
55 * Hudson (tjh@cryptsoft.com).
56 *
57 */
58
59
60/* Calaculates and sets the affine coordinates of an EC_POINT from the given
61 * compressed coordinates.  Uses algorithm 2.3.4 of SEC 1.
62 * Note that the simple implementation only uses affine coordinates.
63 *
64 * This algorithm is patented by Certicom Corp. under US Patent 6,141,420
65 * (for licensing information, contact licensing@certicom.com).
66 * This function is disabled by default and can be enabled by defining the
67 * preprocessor macro OPENSSL_EC_BIN_PT_COMP at Configure-time.
68 */
69int ec_GF2m_simple_set_compressed_coordinates(const EC_GROUP *group, EC_POINT *point,
70	const BIGNUM *x_, int y_bit, BN_CTX *ctx)
71	{
72#ifndef OPENSSL_EC_BIN_PT_COMP
73	ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, ERR_R_DISABLED);
74	return 0;
75#else
76	BN_CTX *new_ctx = NULL;
77	BIGNUM *tmp, *x, *y, *z;
78	int ret = 0, z0;
79
80	/* clear error queue */
81	ERR_clear_error();
82
83	if (ctx == NULL)
84		{
85		ctx = new_ctx = BN_CTX_new();
86		if (ctx == NULL)
87			return 0;
88		}
89
90	y_bit = (y_bit != 0) ? 1 : 0;
91
92	BN_CTX_start(ctx);
93	tmp = BN_CTX_get(ctx);
94	x = BN_CTX_get(ctx);
95	y = BN_CTX_get(ctx);
96	z = BN_CTX_get(ctx);
97	if (z == NULL) goto err;
98
99	if (!BN_GF2m_mod_arr(x, x_, group->poly)) goto err;
100	if (BN_is_zero(x))
101		{
102		if (!BN_GF2m_mod_sqrt_arr(y, &group->b, group->poly, ctx)) goto err;
103		}
104	else
105		{
106		if (!group->meth->field_sqr(group, tmp, x, ctx)) goto err;
107		if (!group->meth->field_div(group, tmp, &group->b, tmp, ctx)) goto err;
108		if (!BN_GF2m_add(tmp, &group->a, tmp)) goto err;
109		if (!BN_GF2m_add(tmp, x, tmp)) goto err;
110		if (!BN_GF2m_mod_solve_quad_arr(z, tmp, group->poly, ctx))
111			{
112			unsigned long err = ERR_peek_last_error();
113
114			if (ERR_GET_LIB(err) == ERR_LIB_BN && ERR_GET_REASON(err) == BN_R_NO_SOLUTION)
115				{
116				ERR_clear_error();
117				ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, EC_R_INVALID_COMPRESSED_POINT);
118				}
119			else
120				ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, ERR_R_BN_LIB);
121			goto err;
122			}
123		z0 = (BN_is_odd(z)) ? 1 : 0;
124		if (!group->meth->field_mul(group, y, x, z, ctx)) goto err;
125		if (z0 != y_bit)
126			{
127			if (!BN_GF2m_add(y, y, x)) goto err;
128			}
129		}
130
131	if (!EC_POINT_set_affine_coordinates_GF2m(group, point, x, y, ctx)) goto err;
132
133	ret = 1;
134
135 err:
136	BN_CTX_end(ctx);
137	if (new_ctx != NULL)
138		BN_CTX_free(new_ctx);
139	return ret;
140#endif
141	}
142