/src/openssl111/crypto/ec/ec2_oct.c

Source (jump to first uncovered line)
/*
 * Copyright 2011-2021 The OpenSSL Project Authors. All Rights Reserved.
 * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
 *
 * Licensed under the OpenSSL license (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <openssl/err.h>

#include "ec_local.h"

#ifndef OPENSSL_NO_EC2M

/*-
 * Calculates and sets the affine coordinates of an EC_POINT from the given
 * compressed coordinates.  Uses algorithm 2.3.4 of SEC 1.
 * Note that the simple implementation only uses affine coordinates.
 *
 * The method is from the following publication:
 *
 *     Harper, Menezes, Vanstone:
 *     "Public-Key Cryptosystems with Very Small Key Lengths",
 *     EUROCRYPT '92, Springer-Verlag LNCS 658,
 *     published February 1993
 *
 * US Patents 6,141,420 and 6,618,483 (Vanstone, Mullin, Agnew) describe
 * the same method, but claim no priority date earlier than July 29, 1994
 * (and additionally fail to cite the EUROCRYPT '92 publication as prior art).
 */
int ec_GF2m_simple_set_compressed_coordinates(const EC_GROUP *group,
                                              EC_POINT *point,
                                              const BIGNUM *x_, int y_bit,
                                              BN_CTX *ctx)
{
    BN_CTX *new_ctx = NULL;
    BIGNUM *tmp, *x, *y, *z;
    int ret = 0, z0;

    /* clear error queue */
    ERR_clear_error();

    if (ctx == NULL) {
        ctx = new_ctx = BN_CTX_new();
        if (ctx == NULL)
            return 0;
    }

    y_bit = (y_bit != 0) ? 1 : 0;

    BN_CTX_start(ctx);
    tmp = BN_CTX_get(ctx);
    x = BN_CTX_get(ctx);
    y = BN_CTX_get(ctx);
    z = BN_CTX_get(ctx);
    if (z == NULL)
        goto err;

    if (!BN_GF2m_mod_arr(x, x_, group->poly))
        goto err;
    if (BN_is_zero(x)) {
        if (!BN_GF2m_mod_sqrt_arr(y, group->b, group->poly, ctx))
            goto err;
    } else {
        if (!group->meth->field_sqr(group, tmp, x, ctx))
            goto err;
        if (!group->meth->field_div(group, tmp, group->b, tmp, ctx))
            goto err;
        if (!BN_GF2m_add(tmp, group->a, tmp))
            goto err;
        if (!BN_GF2m_add(tmp, x, tmp))
            goto err;
        if (!BN_GF2m_mod_solve_quad_arr(z, tmp, group->poly, ctx)) {
            unsigned long err = ERR_peek_last_error();

            if (ERR_GET_LIB(err) == ERR_LIB_BN
                && ERR_GET_REASON(err) == BN_R_NO_SOLUTION) {
                ERR_clear_error();
                ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES,
                      EC_R_INVALID_COMPRESSED_POINT);
            } else
                ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES,
                      ERR_R_BN_LIB);
            goto err;
        }
        z0 = (BN_is_odd(z)) ? 1 : 0;
        if (!group->meth->field_mul(group, y, x, z, ctx))
            goto err;
        if (z0 != y_bit) {
            if (!BN_GF2m_add(y, y, x))
                goto err;
        }
    }

    if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
        goto err;

    ret = 1;

 err:
    BN_CTX_end(ctx);
    BN_CTX_free(new_ctx);
    return ret;
}

/*
 * Converts an EC_POINT to an octet string. If buf is NULL, the encoded
 * length will be returned. If the length len of buf is smaller than required
 * an error will be returned.
 */
size_t ec_GF2m_simple_point2oct(const EC_GROUP *group, const EC_POINT *point,
                                point_conversion_form_t form,
                                unsigned char *buf, size_t len, BN_CTX *ctx)
{
    size_t ret;
    BN_CTX *new_ctx = NULL;
    int used_ctx = 0;
    BIGNUM *x, *y, *yxi;
    size_t field_len, i, skip;

    if ((form != POINT_CONVERSION_COMPRESSED)
        && (form != POINT_CONVERSION_UNCOMPRESSED)
        && (form != POINT_CONVERSION_HYBRID)) {
        ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_INVALID_FORM);
        goto err;
    }

    if (EC_POINT_is_at_infinity(group, point)) {
        /* encodes to a single 0 octet */
        if (buf != NULL) {
            if (len < 1) {
                ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
                return 0;
            }
            buf[0] = 0;
        }
        return 1;
    }

    /* ret := required output buffer length */
    field_len = (EC_GROUP_get_degree(group) + 7) / 8;
    ret =
        (form ==
         POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;

    /* if 'buf' is NULL, just return required length */
    if (buf != NULL) {
        if (len < ret) {
            ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
            goto err;
        }

        if (ctx == NULL) {
            ctx = new_ctx = BN_CTX_new();
            if (ctx == NULL)
                return 0;
        }

        BN_CTX_start(ctx);
        used_ctx = 1;
        x = BN_CTX_get(ctx);
        y = BN_CTX_get(ctx);
        yxi = BN_CTX_get(ctx);
        if (yxi == NULL)
            goto err;

        if (!EC_POINT_get_affine_coordinates(group, point, x, y, ctx))
            goto err;

        buf[0] = form;
        if ((form != POINT_CONVERSION_UNCOMPRESSED) && !BN_is_zero(x)) {
            if (!group->meth->field_div(group, yxi, y, x, ctx))
                goto err;
            if (BN_is_odd(yxi))
                buf[0]++;
        }

        i = 1;

        skip = field_len - BN_num_bytes(x);
        if (skip > field_len) {
            ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
            goto err;
        }
        while (skip > 0) {
            buf[i++] = 0;
            skip--;
        }
        skip = BN_bn2bin(x, buf + i);
        i += skip;
        if (i != 1 + field_len) {
            ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
            goto err;
        }

        if (form == POINT_CONVERSION_UNCOMPRESSED
            || form == POINT_CONVERSION_HYBRID) {
            skip = field_len - BN_num_bytes(y);
            if (skip > field_len) {
                ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
                goto err;
            }
            while (skip > 0) {
                buf[i++] = 0;
                skip--;
            }
            skip = BN_bn2bin(y, buf + i);
            i += skip;
        }

        if (i != ret) {
            ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
            goto err;
        }
    }

    if (used_ctx)
        BN_CTX_end(ctx);
    BN_CTX_free(new_ctx);
    return ret;

 err:
    if (used_ctx)
        BN_CTX_end(ctx);
    BN_CTX_free(new_ctx);
    return 0;
}

/*
 * Converts an octet string representation to an EC_POINT. Note that the
 * simple implementation only uses affine coordinates.
 */
int ec_GF2m_simple_oct2point(const EC_GROUP *group, EC_POINT *point,
                             const unsigned char *buf, size_t len,
                             BN_CTX *ctx)
{
    point_conversion_form_t form;
    int y_bit, m;
    BN_CTX *new_ctx = NULL;
    BIGNUM *x, *y, *yxi;
    size_t field_len, enc_len;
    int ret = 0;

    if (len == 0) {
        ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_BUFFER_TOO_SMALL);
        return 0;
    }

    /*
     * The first octet is the point converison octet PC, see X9.62, page 4
     * and section 4.4.2.  It must be:
     *     0x00          for the point at infinity
     *     0x02 or 0x03  for compressed form
     *     0x04          for uncompressed form
     *     0x06 or 0x07  for hybrid form.
     * For compressed or hybrid forms, we store the last bit of buf[0] as
     * y_bit and clear it from buf[0] so as to obtain a POINT_CONVERSION_*.
     * We error if buf[0] contains any but the above values.
     */
    y_bit = buf[0] & 1;
    form = buf[0] & ~1U;

    if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED)
        && (form != POINT_CONVERSION_UNCOMPRESSED)
        && (form != POINT_CONVERSION_HYBRID)) {
        ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
        return 0;
    }
    if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) {
        ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
        return 0;
    }

    /* The point at infinity is represented by a single zero octet. */
    if (form == 0) {
        if (len != 1) {
            ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
            return 0;
        }

        return EC_POINT_set_to_infinity(group, point);
    }

    m = EC_GROUP_get_degree(group);
    field_len = (m + 7) / 8;
    enc_len =
        (form ==
         POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;

    if (len != enc_len) {
        ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
        return 0;
    }

    if (ctx == NULL) {
        ctx = new_ctx = BN_CTX_new();
        if (ctx == NULL)
            return 0;
    }

    BN_CTX_start(ctx);
    x = BN_CTX_get(ctx);
    y = BN_CTX_get(ctx);
    yxi = BN_CTX_get(ctx);
    if (yxi == NULL)
        goto err;

    if (!BN_bin2bn(buf + 1, field_len, x))
        goto err;
    if (BN_num_bits(x) > m) {
        ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
        goto err;
    }

    if (form == POINT_CONVERSION_COMPRESSED) {
        if (!EC_POINT_set_compressed_coordinates(group, point, x, y_bit, ctx))
            goto err;
    } else {
        if (!BN_bin2bn(buf + 1 + field_len, field_len, y))
            goto err;
        if (BN_num_bits(y) > m) {
            ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
            goto err;
        }
        if (form == POINT_CONVERSION_HYBRID) {
            /*
             * Check that the form in the encoding was set correctly
             * according to X9.62 4.4.2.a, 4(c), see also first paragraph
             * of X9.62, 4.4.1.b.
             */
            if (BN_is_zero(x)) {
                if (y_bit != 0) {
                    ECerr(ERR_LIB_EC, EC_R_INVALID_ENCODING);
                    goto err;
                }
            } else {
                if (!group->meth->field_div(group, yxi, y, x, ctx))
                    goto err;
                if (y_bit != BN_is_odd(yxi)) {
                    ECerr(ERR_LIB_EC, EC_R_INVALID_ENCODING);
                    goto err;
                }
            }
        }

        /*
         * EC_POINT_set_affine_coordinates is responsible for checking that
         * the point is on the curve.
         */
        if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
            goto err;
    }

    ret = 1;

 err:
    BN_CTX_end(ctx);
    BN_CTX_free(new_ctx);
    return ret;
}
#endif

Coverage Report

Created: 2023-06-08 06:41

Line	Count	Source (jump to first uncovered line)
1		/*
2		* Copyright 2011-2021 The OpenSSL Project Authors. All Rights Reserved.
3		* Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
4		*
5		* Licensed under the OpenSSL license (the "License"). You may not use
6		* this file except in compliance with the License. You can obtain a copy
7		* in the file LICENSE in the source distribution or at
8		* https://www.openssl.org/source/license.html
9		*/
10
11		#include <openssl/err.h>
12
13		#include "ec_local.h"
14
15		#ifndef OPENSSL_NO_EC2M
16
17		/*-
18		* Calculates and sets the affine coordinates of an EC_POINT from the given
19		* compressed coordinates. Uses algorithm 2.3.4 of SEC 1.
20		* Note that the simple implementation only uses affine coordinates.
21		*
22		* The method is from the following publication:
23		*
24		* Harper, Menezes, Vanstone:
25		* "Public-Key Cryptosystems with Very Small Key Lengths",
26		* EUROCRYPT '92, Springer-Verlag LNCS 658,
27		* published February 1993
28		*
29		* US Patents 6,141,420 and 6,618,483 (Vanstone, Mullin, Agnew) describe
30		* the same method, but claim no priority date earlier than July 29, 1994
31		* (and additionally fail to cite the EUROCRYPT '92 publication as prior art).
32		*/
33		int ec_GF2m_simple_set_compressed_coordinates(const EC_GROUP *group,
34		EC_POINT *point,
35		const BIGNUM *x_, int y_bit,
36		BN_CTX *ctx)
37	0	{
38	0	BN_CTX *new_ctx = NULL;
39	0	BIGNUM tmp, x, y, z;
40	0	int ret = 0, z0;
41
42		/* clear error queue */
43	0	ERR_clear_error();
44
45	0	if (ctx == NULL) {
46	0	ctx = new_ctx = BN_CTX_new();
47	0	if (ctx == NULL)
48	0	return 0;
49	0	}
50
51	0	y_bit = (y_bit != 0) ? 1 : 0;
52
53	0	BN_CTX_start(ctx);
54	0	tmp = BN_CTX_get(ctx);
55	0	x = BN_CTX_get(ctx);
56	0	y = BN_CTX_get(ctx);
57	0	z = BN_CTX_get(ctx);
58	0	if (z == NULL)
59	0	goto err;
60
61	0	if (!BN_GF2m_mod_arr(x, x_, group->poly))
62	0	goto err;
63	0	if (BN_is_zero(x)) {
64	0	if (!BN_GF2m_mod_sqrt_arr(y, group->b, group->poly, ctx))
65	0	goto err;
66	0	} else {
67	0	if (!group->meth->field_sqr(group, tmp, x, ctx))
68	0	goto err;
69	0	if (!group->meth->field_div(group, tmp, group->b, tmp, ctx))
70	0	goto err;
71	0	if (!BN_GF2m_add(tmp, group->a, tmp))
72	0	goto err;
73	0	if (!BN_GF2m_add(tmp, x, tmp))
74	0	goto err;
75	0	if (!BN_GF2m_mod_solve_quad_arr(z, tmp, group->poly, ctx)) {
76	0	unsigned long err = ERR_peek_last_error();
77
78	0	if (ERR_GET_LIB(err) == ERR_LIB_BN
79	0	&& ERR_GET_REASON(err) == BN_R_NO_SOLUTION) {
80	0	ERR_clear_error();
81	0	ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES,
82	0	EC_R_INVALID_COMPRESSED_POINT);
83	0	} else
84	0	ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES,
85	0	ERR_R_BN_LIB);
86	0	goto err;
87	0	}
88	0	z0 = (BN_is_odd(z)) ? 1 : 0;
89	0	if (!group->meth->field_mul(group, y, x, z, ctx))
90	0	goto err;
91	0	if (z0 != y_bit) {
92	0	if (!BN_GF2m_add(y, y, x))
93	0	goto err;
94	0	}
95	0	}
96
97	0	if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
98	0	goto err;
99
100	0	ret = 1;
101
102	0	err:
103	0	BN_CTX_end(ctx);
104	0	BN_CTX_free(new_ctx);
105	0	return ret;
106	0	}
107
108		/*
109		* Converts an EC_POINT to an octet string. If buf is NULL, the encoded
110		* length will be returned. If the length len of buf is smaller than required
111		* an error will be returned.
112		*/
113		size_t ec_GF2m_simple_point2oct(const EC_GROUP group, const EC_POINT point,
114		point_conversion_form_t form,
115		unsigned char buf, size_t len, BN_CTX ctx)
116	0	{
117	0	size_t ret;
118	0	BN_CTX *new_ctx = NULL;
119	0	int used_ctx = 0;
120	0	BIGNUM x, y, *yxi;
121	0	size_t field_len, i, skip;
122
123	0	if ((form != POINT_CONVERSION_COMPRESSED)
124	0	&& (form != POINT_CONVERSION_UNCOMPRESSED)
125	0	&& (form != POINT_CONVERSION_HYBRID)) {
126	0	ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_INVALID_FORM);
127	0	goto err;
128	0	}
129
130	0	if (EC_POINT_is_at_infinity(group, point)) {
131		/* encodes to a single 0 octet */
132	0	if (buf != NULL) {
133	0	if (len < 1) {
134	0	ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
135	0	return 0;
136	0	}
137	0	buf[0] = 0;
138	0	}
139	0	return 1;
140	0	}
141
142		/* ret := required output buffer length */
143	0	field_len = (EC_GROUP_get_degree(group) + 7) / 8;
144	0	ret =
145	0	(form ==
146	0	POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
147
148		/* if 'buf' is NULL, just return required length */
149	0	if (buf != NULL) {
150	0	if (len < ret) {
151	0	ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
152	0	goto err;
153	0	}
154
155	0	if (ctx == NULL) {
156	0	ctx = new_ctx = BN_CTX_new();
157	0	if (ctx == NULL)
158	0	return 0;
159	0	}
160
161	0	BN_CTX_start(ctx);
162	0	used_ctx = 1;
163	0	x = BN_CTX_get(ctx);
164	0	y = BN_CTX_get(ctx);
165	0	yxi = BN_CTX_get(ctx);
166	0	if (yxi == NULL)
167	0	goto err;
168
169	0	if (!EC_POINT_get_affine_coordinates(group, point, x, y, ctx))
170	0	goto err;
171
172	0	buf[0] = form;
173	0	if ((form != POINT_CONVERSION_UNCOMPRESSED) && !BN_is_zero(x)) {
174	0	if (!group->meth->field_div(group, yxi, y, x, ctx))
175	0	goto err;
176	0	if (BN_is_odd(yxi))
177	0	buf[0]++;
178	0	}
179
180	0	i = 1;
181
182	0	skip = field_len - BN_num_bytes(x);
183	0	if (skip > field_len) {
184	0	ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
185	0	goto err;
186	0	}
187	0	while (skip > 0) {
188	0	buf[i++] = 0;
189	0	skip--;
190	0	}
191	0	skip = BN_bn2bin(x, buf + i);
192	0	i += skip;
193	0	if (i != 1 + field_len) {
194	0	ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
195	0	goto err;
196	0	}
197
198	0	if (form == POINT_CONVERSION_UNCOMPRESSED
199	0	\|\| form == POINT_CONVERSION_HYBRID) {
200	0	skip = field_len - BN_num_bytes(y);
201	0	if (skip > field_len) {
202	0	ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
203	0	goto err;
204	0	}
205	0	while (skip > 0) {
206	0	buf[i++] = 0;
207	0	skip--;
208	0	}
209	0	skip = BN_bn2bin(y, buf + i);
210	0	i += skip;
211	0	}
212
213	0	if (i != ret) {
214	0	ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
215	0	goto err;
216	0	}
217	0	}
218
219	0	if (used_ctx)
220	0	BN_CTX_end(ctx);
221	0	BN_CTX_free(new_ctx);
222	0	return ret;
223
224	0	err:
225	0	if (used_ctx)
226	0	BN_CTX_end(ctx);
227	0	BN_CTX_free(new_ctx);
228	0	return 0;
229	0	}
230
231		/*
232		* Converts an octet string representation to an EC_POINT. Note that the
233		* simple implementation only uses affine coordinates.
234		*/
235		int ec_GF2m_simple_oct2point(const EC_GROUP group, EC_POINT point,
236		const unsigned char *buf, size_t len,
237		BN_CTX *ctx)
238	0	{
239	0	point_conversion_form_t form;
240	0	int y_bit, m;
241	0	BN_CTX *new_ctx = NULL;
242	0	BIGNUM x, y, *yxi;
243	0	size_t field_len, enc_len;
244	0	int ret = 0;
245
246	0	if (len == 0) {
247	0	ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_BUFFER_TOO_SMALL);
248	0	return 0;
249	0	}
250
251		/*
252		* The first octet is the point converison octet PC, see X9.62, page 4
253		* and section 4.4.2. It must be:
254		* 0x00 for the point at infinity
255		* 0x02 or 0x03 for compressed form
256		* 0x04 for uncompressed form
257		* 0x06 or 0x07 for hybrid form.
258		* For compressed or hybrid forms, we store the last bit of buf[0] as
259		* y_bit and clear it from buf[0] so as to obtain a POINT_CONVERSION_*.
260		* We error if buf[0] contains any but the above values.
261		*/
262	0	y_bit = buf[0] & 1;
263	0	form = buf[0] & ~1U;
264
265	0	if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED)
266	0	&& (form != POINT_CONVERSION_UNCOMPRESSED)
267	0	&& (form != POINT_CONVERSION_HYBRID)) {
268	0	ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
269	0	return 0;
270	0	}
271	0	if ((form == 0 \|\| form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) {
272	0	ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
273	0	return 0;
274	0	}
275
276		/* The point at infinity is represented by a single zero octet. */
277	0	if (form == 0) {
278	0	if (len != 1) {
279	0	ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
280	0	return 0;
281	0	}
282
283	0	return EC_POINT_set_to_infinity(group, point);
284	0	}
285
286	0	m = EC_GROUP_get_degree(group);
287	0	field_len = (m + 7) / 8;
288	0	enc_len =
289	0	(form ==
290	0	POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
291
292	0	if (len != enc_len) {
293	0	ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
294	0	return 0;
295	0	}
296
297	0	if (ctx == NULL) {
298	0	ctx = new_ctx = BN_CTX_new();
299	0	if (ctx == NULL)
300	0	return 0;
301	0	}
302
303	0	BN_CTX_start(ctx);
304	0	x = BN_CTX_get(ctx);
305	0	y = BN_CTX_get(ctx);
306	0	yxi = BN_CTX_get(ctx);
307	0	if (yxi == NULL)
308	0	goto err;
309
310	0	if (!BN_bin2bn(buf + 1, field_len, x))
311	0	goto err;
312	0	if (BN_num_bits(x) > m) {
313	0	ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
314	0	goto err;
315	0	}
316
317	0	if (form == POINT_CONVERSION_COMPRESSED) {
318	0	if (!EC_POINT_set_compressed_coordinates(group, point, x, y_bit, ctx))
319	0	goto err;
320	0	} else {
321	0	if (!BN_bin2bn(buf + 1 + field_len, field_len, y))
322	0	goto err;
323	0	if (BN_num_bits(y) > m) {
324	0	ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
325	0	goto err;
326	0	}
327	0	if (form == POINT_CONVERSION_HYBRID) {
328		/*
329		* Check that the form in the encoding was set correctly
330		* according to X9.62 4.4.2.a, 4(c), see also first paragraph
331		* of X9.62, 4.4.1.b.
332		*/
333	0	if (BN_is_zero(x)) {
334	0	if (y_bit != 0) {
335	0	ECerr(ERR_LIB_EC, EC_R_INVALID_ENCODING);
336	0	goto err;
337	0	}
338	0	} else {
339	0	if (!group->meth->field_div(group, yxi, y, x, ctx))
340	0	goto err;
341	0	if (y_bit != BN_is_odd(yxi)) {
342	0	ECerr(ERR_LIB_EC, EC_R_INVALID_ENCODING);
343	0	goto err;
344	0	}
345	0	}
346	0	}
347
348		/*
349		* EC_POINT_set_affine_coordinates is responsible for checking that
350		* the point is on the curve.
351		*/
352	0	if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
353	0	goto err;
354	0	}
355
356	0	ret = 1;
357
358	0	err:
359	0	BN_CTX_end(ctx);
360	0	BN_CTX_free(new_ctx);
361	0	return ret;
362	0	}
363		#endif