/src/libressl/crypto/ec/ecp_oct.c

Source (jump to first uncovered line)
/* $OpenBSD: ecp_oct.c,v 1.14 2021/04/20 17:32:57 tb Exp $ */
/* Includes code written by Lenka Fibikova <fibikova@exp-math.uni-essen.de>
 * for the OpenSSL project.
 * Includes code written by Bodo Moeller for the OpenSSL project.
*/
/* ====================================================================
 * Copyright (c) 1998-2002 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    openssl-core@openssl.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */
/* ====================================================================
 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
 * Portions of this software developed by SUN MICROSYSTEMS, INC.,
 * and contributed to the OpenSSL project.
 */

#include <openssl/err.h>

#include "ec_lcl.h"

int 
ec_GFp_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 *tmp1, *tmp2, *x, *y;
  int ret = 0;

  /* 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);

  BN_CTX_start(ctx);
  if ((tmp1 = BN_CTX_get(ctx)) == NULL)
    goto err;
  if ((tmp2 = BN_CTX_get(ctx)) == NULL)
    goto err;
  if ((x = BN_CTX_get(ctx)) == NULL)
    goto err;
  if ((y = BN_CTX_get(ctx)) == NULL)
    goto err;

  /*
   * Recover y.  We have a Weierstrass equation y^2 = x^3 + a*x + b, so
   * y  is one of the square roots of  x^3 + a*x + b.
   */

  /* tmp1 := x^3 */
  if (!BN_nnmod(x, x_, &group->field, ctx))
    goto err;
  if (group->meth->field_decode == 0) {
    /* field_{sqr,mul} work on standard representation */
    if (!group->meth->field_sqr(group, tmp2, x_, ctx))
      goto err;
    if (!group->meth->field_mul(group, tmp1, tmp2, x_, ctx))
      goto err;
  } else {
    if (!BN_mod_sqr(tmp2, x_, &group->field, ctx))
      goto err;
    if (!BN_mod_mul(tmp1, tmp2, x_, &group->field, ctx))
      goto err;
  }

  /* tmp1 := tmp1 + a*x */
  if (group->a_is_minus3) {
    if (!BN_mod_lshift1_quick(tmp2, x, &group->field))
      goto err;
    if (!BN_mod_add_quick(tmp2, tmp2, x, &group->field))
      goto err;
    if (!BN_mod_sub_quick(tmp1, tmp1, tmp2, &group->field))
      goto err;
  } else {
    if (group->meth->field_decode) {
      if (!group->meth->field_decode(group, tmp2, &group->a, ctx))
        goto err;
      if (!BN_mod_mul(tmp2, tmp2, x, &group->field, ctx))
        goto err;
    } else {
      /* field_mul works on standard representation */
      if (!group->meth->field_mul(group, tmp2, &group->a, x, ctx))
        goto err;
    }

    if (!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field))
      goto err;
  }

  /* tmp1 := tmp1 + b */
  if (group->meth->field_decode) {
    if (!group->meth->field_decode(group, tmp2, &group->b, ctx))
      goto err;
    if (!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field))
      goto err;
  } else {
    if (!BN_mod_add_quick(tmp1, tmp1, &group->b, &group->field))
      goto err;
  }

  if (!BN_mod_sqrt(y, tmp1, &group->field, ctx)) {
    unsigned long err = ERR_peek_last_error();

    if (ERR_GET_LIB(err) == ERR_LIB_BN && ERR_GET_REASON(err) == BN_R_NOT_A_SQUARE) {
      ERR_clear_error();
      ECerror(EC_R_INVALID_COMPRESSED_POINT);
    } else
      ECerror(ERR_R_BN_LIB);
    goto err;
  }
  if (y_bit != BN_is_odd(y)) {
    if (BN_is_zero(y)) {
      int kron;

      kron = BN_kronecker(x, &group->field, ctx);
      if (kron == -2)
        goto err;

      if (kron == 1)
        ECerror(EC_R_INVALID_COMPRESSION_BIT);
      else
        /*
         * BN_mod_sqrt() should have cought this
         * error (not a square)
         */
        ECerror(EC_R_INVALID_COMPRESSED_POINT);
      goto err;
    }
    if (!BN_usub(y, &group->field, y))
      goto err;
  }
  if (y_bit != BN_is_odd(y)) {
    ECerror(ERR_R_INTERNAL_ERROR);
    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;
}


size_t 
ec_GFp_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;
  size_t field_len, i, skip;

  if ((form != POINT_CONVERSION_COMPRESSED)
      && (form != POINT_CONVERSION_UNCOMPRESSED)
      && (form != POINT_CONVERSION_HYBRID)) {
    ECerror(EC_R_INVALID_FORM);
    goto err;
  }
  if (EC_POINT_is_at_infinity(group, point) > 0) {
    /* encodes to a single 0 octet */
    if (buf != NULL) {
      if (len < 1) {
        ECerror(EC_R_BUFFER_TOO_SMALL);
        return 0;
      }
      buf[0] = 0;
    }
    return 1;
  }
  /* ret := required output buffer length */
  field_len = BN_num_bytes(&group->field);
  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) {
      ECerror(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;
    if ((x = BN_CTX_get(ctx)) == NULL)
      goto err;
    if ((y = BN_CTX_get(ctx)) == NULL)
      goto err;

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

    if ((form == POINT_CONVERSION_COMPRESSED || form == POINT_CONVERSION_HYBRID) && BN_is_odd(y))
      buf[0] = form + 1;
    else
      buf[0] = form;

    i = 1;

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


int 
ec_GFp_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;
  BN_CTX *new_ctx = NULL;
  BIGNUM *x, *y;
  size_t field_len, enc_len;
  int ret = 0;

  if (len == 0) {
    ECerror(EC_R_BUFFER_TOO_SMALL);
    return 0;
  }
  form = buf[0];
  y_bit = form & 1;
  form = form & ~1U;
  if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED)
      && (form != POINT_CONVERSION_UNCOMPRESSED)
      && (form != POINT_CONVERSION_HYBRID)) {
    ECerror(EC_R_INVALID_ENCODING);
    return 0;
  }
  if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) {
    ECerror(EC_R_INVALID_ENCODING);
    return 0;
  }
  if (form == 0) {
    if (len != 1) {
      ECerror(EC_R_INVALID_ENCODING);
      return 0;
    }
    return EC_POINT_set_to_infinity(group, point);
  }
  field_len = BN_num_bytes(&group->field);
  enc_len = (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;

  if (len != enc_len) {
    ECerror(EC_R_INVALID_ENCODING);
    return 0;
  }
  if (ctx == NULL) {
    ctx = new_ctx = BN_CTX_new();
    if (ctx == NULL)
      return 0;
  }
  BN_CTX_start(ctx);
  if ((x = BN_CTX_get(ctx)) == NULL)
    goto err;
  if ((y = BN_CTX_get(ctx)) == NULL)
    goto err;

  if (!BN_bin2bn(buf + 1, field_len, x))
    goto err;
  if (BN_ucmp(x, &group->field) >= 0) {
    ECerror(EC_R_INVALID_ENCODING);
    goto err;
  }
  if (form == POINT_CONVERSION_COMPRESSED) {
    /*
     * EC_POINT_set_compressed_coordinates checks that the point
     * is on the curve as required by X9.62.
     */
    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_ucmp(y, &group->field) >= 0) {
      ECerror(EC_R_INVALID_ENCODING);
      goto err;
    }
    if (form == POINT_CONVERSION_HYBRID) {
      if (y_bit != BN_is_odd(y)) {
        ECerror(EC_R_INVALID_ENCODING);
        goto err;
      }
    }
    /*
     * EC_POINT_set_affine_coordinates checks that the point is
     * on the curve as required by X9.62.
     */
    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;
}

Coverage Report

Created: 2022-08-24 06:30

Line	Count	Source (jump to first uncovered line)
1		/* $OpenBSD: ecp_oct.c,v 1.14 2021/04/20 17:32:57 tb Exp $ */
2		/* Includes code written by Lenka Fibikova <fibikova@exp-math.uni-essen.de>
3		* for the OpenSSL project.
4		* Includes code written by Bodo Moeller for the OpenSSL project.
5		*/
6		/* ====================================================================
7		* Copyright (c) 1998-2002 The OpenSSL Project. All rights reserved.
8		*
9		* Redistribution and use in source and binary forms, with or without
10		* modification, are permitted provided that the following conditions
11		* are met:
12		*
13		* 1. Redistributions of source code must retain the above copyright
14		* notice, this list of conditions and the following disclaimer.
15		*
16		* 2. Redistributions in binary form must reproduce the above copyright
17		* notice, this list of conditions and the following disclaimer in
18		* the documentation and/or other materials provided with the
19		* distribution.
20		*
21		* 3. All advertising materials mentioning features or use of this
22		* software must display the following acknowledgment:
23		* "This product includes software developed by the OpenSSL Project
24		* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
25		*
26		* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
27		* endorse or promote products derived from this software without
28		* prior written permission. For written permission, please contact
29		* openssl-core@openssl.org.
30		*
31		* 5. Products derived from this software may not be called "OpenSSL"
32		* nor may "OpenSSL" appear in their names without prior written
33		* permission of the OpenSSL Project.
34		*
35		* 6. Redistributions of any form whatsoever must retain the following
36		* acknowledgment:
37		* "This product includes software developed by the OpenSSL Project
38		* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
39		*
40		* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
41		* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42		* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
43		* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
44		* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
45		* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
46		* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
47		* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48		* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
49		* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
50		* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
51		* OF THE POSSIBILITY OF SUCH DAMAGE.
52		* ====================================================================
53		*
54		* This product includes cryptographic software written by Eric Young
55		* (eay@cryptsoft.com). This product includes software written by Tim
56		* Hudson (tjh@cryptsoft.com).
57		*
58		*/
59		/* ====================================================================
60		* Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
61		* Portions of this software developed by SUN MICROSYSTEMS, INC.,
62		* and contributed to the OpenSSL project.
63		*/
64
65		#include <openssl/err.h>
66
67		#include "ec_lcl.h"
68
69		int
70		ec_GFp_simple_set_compressed_coordinates(const EC_GROUP * group,
71		EC_POINT * point, const BIGNUM * x_, int y_bit, BN_CTX * ctx)
72	0	{
73	0	BN_CTX *new_ctx = NULL;
74	0	BIGNUM tmp1, tmp2, x, y;
75	0	int ret = 0;
76
77		/* clear error queue */
78	0	ERR_clear_error();
79
80	0	if (ctx == NULL) {
81	0	ctx = new_ctx = BN_CTX_new();
82	0	if (ctx == NULL)
83	0	return 0;
84	0	}
85	0	y_bit = (y_bit != 0);
86
87	0	BN_CTX_start(ctx);
88	0	if ((tmp1 = BN_CTX_get(ctx)) == NULL)
89	0	goto err;
90	0	if ((tmp2 = BN_CTX_get(ctx)) == NULL)
91	0	goto err;
92	0	if ((x = BN_CTX_get(ctx)) == NULL)
93	0	goto err;
94	0	if ((y = BN_CTX_get(ctx)) == NULL)
95	0	goto err;
96
97		/*
98		* Recover y. We have a Weierstrass equation y^2 = x^3 + a*x + b, so
99		* y is one of the square roots of x^3 + a*x + b.
100		*/
101
102		/* tmp1 := x^3 */
103	0	if (!BN_nnmod(x, x_, &group->field, ctx))
104	0	goto err;
105	0	if (group->meth->field_decode == 0) {
106		/* field_{sqr,mul} work on standard representation */
107	0	if (!group->meth->field_sqr(group, tmp2, x_, ctx))
108	0	goto err;
109	0	if (!group->meth->field_mul(group, tmp1, tmp2, x_, ctx))
110	0	goto err;
111	0	} else {
112	0	if (!BN_mod_sqr(tmp2, x_, &group->field, ctx))
113	0	goto err;
114	0	if (!BN_mod_mul(tmp1, tmp2, x_, &group->field, ctx))
115	0	goto err;
116	0	}
117
118		/* tmp1 := tmp1 + ax /
119	0	if (group->a_is_minus3) {
120	0	if (!BN_mod_lshift1_quick(tmp2, x, &group->field))
121	0	goto err;
122	0	if (!BN_mod_add_quick(tmp2, tmp2, x, &group->field))
123	0	goto err;
124	0	if (!BN_mod_sub_quick(tmp1, tmp1, tmp2, &group->field))
125	0	goto err;
126	0	} else {
127	0	if (group->meth->field_decode) {
128	0	if (!group->meth->field_decode(group, tmp2, &group->a, ctx))
129	0	goto err;
130	0	if (!BN_mod_mul(tmp2, tmp2, x, &group->field, ctx))
131	0	goto err;
132	0	} else {
133		/* field_mul works on standard representation */
134	0	if (!group->meth->field_mul(group, tmp2, &group->a, x, ctx))
135	0	goto err;
136	0	}
137
138	0	if (!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field))
139	0	goto err;
140	0	}
141
142		/* tmp1 := tmp1 + b */
143	0	if (group->meth->field_decode) {
144	0	if (!group->meth->field_decode(group, tmp2, &group->b, ctx))
145	0	goto err;
146	0	if (!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field))
147	0	goto err;
148	0	} else {
149	0	if (!BN_mod_add_quick(tmp1, tmp1, &group->b, &group->field))
150	0	goto err;
151	0	}
152
153	0	if (!BN_mod_sqrt(y, tmp1, &group->field, ctx)) {
154	0	unsigned long err = ERR_peek_last_error();
155
156	0	if (ERR_GET_LIB(err) == ERR_LIB_BN && ERR_GET_REASON(err) == BN_R_NOT_A_SQUARE) {
157	0	ERR_clear_error();
158	0	ECerror(EC_R_INVALID_COMPRESSED_POINT);
159	0	} else
160	0	ECerror(ERR_R_BN_LIB);
161	0	goto err;
162	0	}
163	0	if (y_bit != BN_is_odd(y)) {
164	0	if (BN_is_zero(y)) {
165	0	int kron;
166
167	0	kron = BN_kronecker(x, &group->field, ctx);
168	0	if (kron == -2)
169	0	goto err;
170
171	0	if (kron == 1)
172	0	ECerror(EC_R_INVALID_COMPRESSION_BIT);
173	0	else
174		/*
175		* BN_mod_sqrt() should have cought this
176		* error (not a square)
177		*/
178	0	ECerror(EC_R_INVALID_COMPRESSED_POINT);
179	0	goto err;
180	0	}
181	0	if (!BN_usub(y, &group->field, y))
182	0	goto err;
183	0	}
184	0	if (y_bit != BN_is_odd(y)) {
185	0	ECerror(ERR_R_INTERNAL_ERROR);
186	0	goto err;
187	0	}
188	0	if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
189	0	goto err;
190
191	0	ret = 1;
192
193	0	err:
194	0	BN_CTX_end(ctx);
195	0	BN_CTX_free(new_ctx);
196	0	return ret;
197	0	}
198
199
200		size_t
201		ec_GFp_simple_point2oct(const EC_GROUP * group, const EC_POINT * point, point_conversion_form_t form,
202		unsigned char buf, size_t len, BN_CTX ctx)
203	0	{
204	0	size_t ret;
205	0	BN_CTX *new_ctx = NULL;
206	0	int used_ctx = 0;
207	0	BIGNUM x, y;
208	0	size_t field_len, i, skip;
209
210	0	if ((form != POINT_CONVERSION_COMPRESSED)
211	0	&& (form != POINT_CONVERSION_UNCOMPRESSED)
212	0	&& (form != POINT_CONVERSION_HYBRID)) {
213	0	ECerror(EC_R_INVALID_FORM);
214	0	goto err;
215	0	}
216	0	if (EC_POINT_is_at_infinity(group, point) > 0) {
217		/* encodes to a single 0 octet */
218	0	if (buf != NULL) {
219	0	if (len < 1) {
220	0	ECerror(EC_R_BUFFER_TOO_SMALL);
221	0	return 0;
222	0	}
223	0	buf[0] = 0;
224	0	}
225	0	return 1;
226	0	}
227		/* ret := required output buffer length */
228	0	field_len = BN_num_bytes(&group->field);
229	0	ret = (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
230
231		/* if 'buf' is NULL, just return required length */
232	0	if (buf != NULL) {
233	0	if (len < ret) {
234	0	ECerror(EC_R_BUFFER_TOO_SMALL);
235	0	goto err;
236	0	}
237	0	if (ctx == NULL) {
238	0	ctx = new_ctx = BN_CTX_new();
239	0	if (ctx == NULL)
240	0	return 0;
241	0	}
242	0	BN_CTX_start(ctx);
243	0	used_ctx = 1;
244	0	if ((x = BN_CTX_get(ctx)) == NULL)
245	0	goto err;
246	0	if ((y = BN_CTX_get(ctx)) == NULL)
247	0	goto err;
248
249	0	if (!EC_POINT_get_affine_coordinates(group, point, x, y, ctx))
250	0	goto err;
251
252	0	if ((form == POINT_CONVERSION_COMPRESSED \|\| form == POINT_CONVERSION_HYBRID) && BN_is_odd(y))
253	0	buf[0] = form + 1;
254	0	else
255	0	buf[0] = form;
256
257	0	i = 1;
258
259	0	skip = field_len - BN_num_bytes(x);
260	0	if (skip > field_len) {
261	0	ECerror(ERR_R_INTERNAL_ERROR);
262	0	goto err;
263	0	}
264	0	while (skip > 0) {
265	0	buf[i++] = 0;
266	0	skip--;
267	0	}
268	0	skip = BN_bn2bin(x, buf + i);
269	0	i += skip;
270	0	if (i != 1 + field_len) {
271	0	ECerror(ERR_R_INTERNAL_ERROR);
272	0	goto err;
273	0	}
274	0	if (form == POINT_CONVERSION_UNCOMPRESSED \|\| form == POINT_CONVERSION_HYBRID) {
275	0	skip = field_len - BN_num_bytes(y);
276	0	if (skip > field_len) {
277	0	ECerror(ERR_R_INTERNAL_ERROR);
278	0	goto err;
279	0	}
280	0	while (skip > 0) {
281	0	buf[i++] = 0;
282	0	skip--;
283	0	}
284	0	skip = BN_bn2bin(y, buf + i);
285	0	i += skip;
286	0	}
287	0	if (i != ret) {
288	0	ECerror(ERR_R_INTERNAL_ERROR);
289	0	goto err;
290	0	}
291	0	}
292	0	if (used_ctx)
293	0	BN_CTX_end(ctx);
294	0	BN_CTX_free(new_ctx);
295	0	return ret;
296
297	0	err:
298	0	if (used_ctx)
299	0	BN_CTX_end(ctx);
300	0	BN_CTX_free(new_ctx);
301	0	return 0;
302	0	}
303
304
305		int
306		ec_GFp_simple_oct2point(const EC_GROUP * group, EC_POINT * point,
307		const unsigned char buf, size_t len, BN_CTX ctx)
308	0	{
309	0	point_conversion_form_t form;
310	0	int y_bit;
311	0	BN_CTX *new_ctx = NULL;
312	0	BIGNUM x, y;
313	0	size_t field_len, enc_len;
314	0	int ret = 0;
315
316	0	if (len == 0) {
317	0	ECerror(EC_R_BUFFER_TOO_SMALL);
318	0	return 0;
319	0	}
320	0	form = buf[0];
321	0	y_bit = form & 1;
322	0	form = form & ~1U;
323	0	if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED)
324	0	&& (form != POINT_CONVERSION_UNCOMPRESSED)
325	0	&& (form != POINT_CONVERSION_HYBRID)) {
326	0	ECerror(EC_R_INVALID_ENCODING);
327	0	return 0;
328	0	}
329	0	if ((form == 0 \|\| form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) {
330	0	ECerror(EC_R_INVALID_ENCODING);
331	0	return 0;
332	0	}
333	0	if (form == 0) {
334	0	if (len != 1) {
335	0	ECerror(EC_R_INVALID_ENCODING);
336	0	return 0;
337	0	}
338	0	return EC_POINT_set_to_infinity(group, point);
339	0	}
340	0	field_len = BN_num_bytes(&group->field);
341	0	enc_len = (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
342
343	0	if (len != enc_len) {
344	0	ECerror(EC_R_INVALID_ENCODING);
345	0	return 0;
346	0	}
347	0	if (ctx == NULL) {
348	0	ctx = new_ctx = BN_CTX_new();
349	0	if (ctx == NULL)
350	0	return 0;
351	0	}
352	0	BN_CTX_start(ctx);
353	0	if ((x = BN_CTX_get(ctx)) == NULL)
354	0	goto err;
355	0	if ((y = BN_CTX_get(ctx)) == NULL)
356	0	goto err;
357
358	0	if (!BN_bin2bn(buf + 1, field_len, x))
359	0	goto err;
360	0	if (BN_ucmp(x, &group->field) >= 0) {
361	0	ECerror(EC_R_INVALID_ENCODING);
362	0	goto err;
363	0	}
364	0	if (form == POINT_CONVERSION_COMPRESSED) {
365		/*
366		* EC_POINT_set_compressed_coordinates checks that the point
367		* is on the curve as required by X9.62.
368		*/
369	0	if (!EC_POINT_set_compressed_coordinates(group, point, x, y_bit, ctx))
370	0	goto err;
371	0	} else {
372	0	if (!BN_bin2bn(buf + 1 + field_len, field_len, y))
373	0	goto err;
374	0	if (BN_ucmp(y, &group->field) >= 0) {
375	0	ECerror(EC_R_INVALID_ENCODING);
376	0	goto err;
377	0	}
378	0	if (form == POINT_CONVERSION_HYBRID) {
379	0	if (y_bit != BN_is_odd(y)) {
380	0	ECerror(EC_R_INVALID_ENCODING);
381	0	goto err;
382	0	}
383	0	}
384		/*
385		* EC_POINT_set_affine_coordinates checks that the point is
386		* on the curve as required by X9.62.
387		*/
388	0	if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
389	0	goto err;
390	0	}
391
392	0	ret = 1;
393
394	0	err:
395	0	BN_CTX_end(ctx);
396	0	BN_CTX_free(new_ctx);
397	0	return ret;
398	0	}