/src/openssl/crypto/ec/ecp_oct.c

Source (jump to first uncovered line)
/*
 * Copyright 2011-2016 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 <openssl/symhacks.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);
    tmp1 = BN_CTX_get(ctx);
    tmp2 = BN_CTX_get(ctx);
    x = BN_CTX_get(ctx);
    y = BN_CTX_get(ctx);
    if (y == 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();
            ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
                  EC_R_INVALID_COMPRESSED_POINT);
        } else
            ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
                  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)
                ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
                      EC_R_INVALID_COMPRESSION_BIT);
            else
                /*
                 * BN_mod_sqrt() should have caught this error (not a square)
                 */
                ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
                      EC_R_INVALID_COMPRESSED_POINT);
            goto err;
        }
        if (!BN_usub(y, group->field, y))
            goto err;
    }
    if (y_bit != BN_is_odd(y)) {
        ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
              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)) {
        ECerr(EC_F_EC_GFP_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_GFP_SIMPLE_POINT2OCT, 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) {
            ECerr(EC_F_EC_GFP_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);
        if (y == 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) {
            ECerr(EC_F_EC_GFP_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_GFP_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_GFP_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_GFP_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;
}

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) {
        ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, 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)) {
        ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
        return 0;
    }
    if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) {
        ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
        return 0;
    }

    if (form == 0) {
        if (len != 1) {
            ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, 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) {
        ECerr(EC_F_EC_GFP_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);
    if (y == NULL)
        goto err;

    if (!BN_bin2bn(buf + 1, field_len, x))
        goto err;
    if (BN_ucmp(x, group->field) >= 0) {
        ECerr(EC_F_EC_GFP_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_ucmp(y, group->field) >= 0) {
            ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
            goto err;
        }
        if (form == POINT_CONVERSION_HYBRID) {
            if (y_bit != BN_is_odd(y)) {
                ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, 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;
}

Coverage Report

Created: 2018-08-29 13:53

Line	Count	Source (jump to first uncovered line)
1		/*
2		* Copyright 2011-2016 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		#include <openssl/symhacks.h>
13
14		#include "ec_lcl.h"
15
16		int ec_GFp_simple_set_compressed_coordinates(const EC_GROUP *group,
17		EC_POINT *point,
18		const BIGNUM *x_, int y_bit,
19		BN_CTX *ctx)
20	0	{
21	0	BN_CTX *new_ctx = NULL;
22	0	BIGNUM tmp1, tmp2, x, y;
23	0	int ret = 0;
24	0
25	0	/* clear error queue */
26	0	ERR_clear_error();
27	0
28	0	if (ctx == NULL) {
29	0	ctx = new_ctx = BN_CTX_new();
30	0	if (ctx == NULL)
31	0	return 0;
32	0	}
33	0
34	0	y_bit = (y_bit != 0);
35	0
36	0	BN_CTX_start(ctx);
37	0	tmp1 = BN_CTX_get(ctx);
38	0	tmp2 = BN_CTX_get(ctx);
39	0	x = BN_CTX_get(ctx);
40	0	y = BN_CTX_get(ctx);
41	0	if (y == NULL)
42	0	goto err;
43	0
44	0	/*-
45	0	* Recover y. We have a Weierstrass equation
46	0	* y^2 = x^3 + a*x + b,
47	0	* so y is one of the square roots of x^3 + a*x + b.
48	0	*/
49	0
50	0	/* tmp1 := x^3 */
51	0	if (!BN_nnmod(x, x_, group->field, ctx))
52	0	goto err;
53	0	if (group->meth->field_decode == 0) {
54	0	/* field_{sqr,mul} work on standard representation */
55	0	if (!group->meth->field_sqr(group, tmp2, x_, ctx))
56	0	goto err;
57	0	if (!group->meth->field_mul(group, tmp1, tmp2, x_, ctx))
58	0	goto err;
59	0	} else {
60	0	if (!BN_mod_sqr(tmp2, x_, group->field, ctx))
61	0	goto err;
62	0	if (!BN_mod_mul(tmp1, tmp2, x_, group->field, ctx))
63	0	goto err;
64	0	}
65	0
66	0	/* tmp1 := tmp1 + ax /
67	0	if (group->a_is_minus3) {
68	0	if (!BN_mod_lshift1_quick(tmp2, x, group->field))
69	0	goto err;
70	0	if (!BN_mod_add_quick(tmp2, tmp2, x, group->field))
71	0	goto err;
72	0	if (!BN_mod_sub_quick(tmp1, tmp1, tmp2, group->field))
73	0	goto err;
74	0	} else {
75	0	if (group->meth->field_decode) {
76	0	if (!group->meth->field_decode(group, tmp2, group->a, ctx))
77	0	goto err;
78	0	if (!BN_mod_mul(tmp2, tmp2, x, group->field, ctx))
79	0	goto err;
80	0	} else {
81	0	/* field_mul works on standard representation */
82	0	if (!group->meth->field_mul(group, tmp2, group->a, x, ctx))
83	0	goto err;
84	0	}
85	0
86	0	if (!BN_mod_add_quick(tmp1, tmp1, tmp2, group->field))
87	0	goto err;
88	0	}
89	0
90	0	/* tmp1 := tmp1 + b */
91	0	if (group->meth->field_decode) {
92	0	if (!group->meth->field_decode(group, tmp2, group->b, ctx))
93	0	goto err;
94	0	if (!BN_mod_add_quick(tmp1, tmp1, tmp2, group->field))
95	0	goto err;
96	0	} else {
97	0	if (!BN_mod_add_quick(tmp1, tmp1, group->b, group->field))
98	0	goto err;
99	0	}
100	0
101	0	if (!BN_mod_sqrt(y, tmp1, group->field, ctx)) {
102	0	unsigned long err = ERR_peek_last_error();
103	0
104	0	if (ERR_GET_LIB(err) == ERR_LIB_BN
105	0	&& ERR_GET_REASON(err) == BN_R_NOT_A_SQUARE) {
106	0	ERR_clear_error();
107	0	ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
108	0	EC_R_INVALID_COMPRESSED_POINT);
109	0	} else
110	0	ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
111	0	ERR_R_BN_LIB);
112	0	goto err;
113	0	}
114	0
115	0	if (y_bit != BN_is_odd(y)) {
116	0	if (BN_is_zero(y)) {
117	0	int kron;
118	0
119	0	kron = BN_kronecker(x, group->field, ctx);
120	0	if (kron == -2)
121	0	goto err;
122	0
123	0	if (kron == 1)
124	0	ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
125	0	EC_R_INVALID_COMPRESSION_BIT);
126	0	else
127	0	/*
128	0	* BN_mod_sqrt() should have caught this error (not a square)
129	0	*/
130	0	ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
131	0	EC_R_INVALID_COMPRESSED_POINT);
132	0	goto err;
133	0	}
134	0	if (!BN_usub(y, group->field, y))
135	0	goto err;
136	0	}
137	0	if (y_bit != BN_is_odd(y)) {
138	0	ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
139	0	ERR_R_INTERNAL_ERROR);
140	0	goto err;
141	0	}
142	0
143	0	if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
144	0	goto err;
145	0
146	0	ret = 1;
147	0
148	0	err:
149	0	BN_CTX_end(ctx);
150	0	BN_CTX_free(new_ctx);
151	0	return ret;
152	0	}
153
154		size_t ec_GFp_simple_point2oct(const EC_GROUP group, const EC_POINT point,
155		point_conversion_form_t form,
156		unsigned char buf, size_t len, BN_CTX ctx)
157	0	{
158	0	size_t ret;
159	0	BN_CTX *new_ctx = NULL;
160	0	int used_ctx = 0;
161	0	BIGNUM x, y;
162	0	size_t field_len, i, skip;
163	0
164	0	if ((form != POINT_CONVERSION_COMPRESSED)
165	0	&& (form != POINT_CONVERSION_UNCOMPRESSED)
166	0	&& (form != POINT_CONVERSION_HYBRID)) {
167	0	ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_INVALID_FORM);
168	0	goto err;
169	0	}
170	0
171	0	if (EC_POINT_is_at_infinity(group, point)) {
172	0	/* encodes to a single 0 octet */
173	0	if (buf != NULL) {
174	0	if (len < 1) {
175	0	ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
176	0	return 0;
177	0	}
178	0	buf[0] = 0;
179	0	}
180	0	return 1;
181	0	}
182	0
183	0	/* ret := required output buffer length */
184	0	field_len = BN_num_bytes(group->field);
185	0	ret =
186	0	(form ==
187	0	POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
188	0
189	0	/* if 'buf' is NULL, just return required length */
190	0	if (buf != NULL) {
191	0	if (len < ret) {
192	0	ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
193	0	goto err;
194	0	}
195	0
196	0	if (ctx == NULL) {
197	0	ctx = new_ctx = BN_CTX_new();
198	0	if (ctx == NULL)
199	0	return 0;
200	0	}
201	0
202	0	BN_CTX_start(ctx);
203	0	used_ctx = 1;
204	0	x = BN_CTX_get(ctx);
205	0	y = BN_CTX_get(ctx);
206	0	if (y == NULL)
207	0	goto err;
208	0
209	0	if (!EC_POINT_get_affine_coordinates(group, point, x, y, ctx))
210	0	goto err;
211	0
212	0	if ((form == POINT_CONVERSION_COMPRESSED
213	0	\|\| form == POINT_CONVERSION_HYBRID) && BN_is_odd(y))
214	0	buf[0] = form + 1;
215	0	else
216	0	buf[0] = form;
217	0
218	0	i = 1;
219	0
220	0	skip = field_len - BN_num_bytes(x);
221	0	if (skip > field_len) {
222	0	ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
223	0	goto err;
224	0	}
225	0	while (skip > 0) {
226	0	buf[i++] = 0;
227	0	skip--;
228	0	}
229	0	skip = BN_bn2bin(x, buf + i);
230	0	i += skip;
231	0	if (i != 1 + field_len) {
232	0	ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
233	0	goto err;
234	0	}
235	0
236	0	if (form == POINT_CONVERSION_UNCOMPRESSED
237	0	\|\| form == POINT_CONVERSION_HYBRID) {
238	0	skip = field_len - BN_num_bytes(y);
239	0	if (skip > field_len) {
240	0	ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
241	0	goto err;
242	0	}
243	0	while (skip > 0) {
244	0	buf[i++] = 0;
245	0	skip--;
246	0	}
247	0	skip = BN_bn2bin(y, buf + i);
248	0	i += skip;
249	0	}
250	0
251	0	if (i != ret) {
252	0	ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
253	0	goto err;
254	0	}
255	0	}
256	0
257	0	if (used_ctx)
258	0	BN_CTX_end(ctx);
259	0	BN_CTX_free(new_ctx);
260	0	return ret;
261	0
262	0	err:
263	0	if (used_ctx)
264	0	BN_CTX_end(ctx);
265	0	BN_CTX_free(new_ctx);
266	0	return 0;
267	0	}
268
269		int ec_GFp_simple_oct2point(const EC_GROUP group, EC_POINT point,
270		const unsigned char buf, size_t len, BN_CTX ctx)
271	0	{
272	0	point_conversion_form_t form;
273	0	int y_bit;
274	0	BN_CTX *new_ctx = NULL;
275	0	BIGNUM x, y;
276	0	size_t field_len, enc_len;
277	0	int ret = 0;
278	0
279	0	if (len == 0) {
280	0	ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_BUFFER_TOO_SMALL);
281	0	return 0;
282	0	}
283	0	form = buf[0];
284	0	y_bit = form & 1;
285	0	form = form & ~1U;
286	0	if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED)
287	0	&& (form != POINT_CONVERSION_UNCOMPRESSED)
288	0	&& (form != POINT_CONVERSION_HYBRID)) {
289	0	ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
290	0	return 0;
291	0	}
292	0	if ((form == 0 \|\| form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) {
293	0	ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
294	0	return 0;
295	0	}
296	0
297	0	if (form == 0) {
298	0	if (len != 1) {
299	0	ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
300	0	return 0;
301	0	}
302	0
303	0	return EC_POINT_set_to_infinity(group, point);
304	0	}
305	0
306	0	field_len = BN_num_bytes(group->field);
307	0	enc_len =
308	0	(form ==
309	0	POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
310	0
311	0	if (len != enc_len) {
312	0	ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
313	0	return 0;
314	0	}
315	0
316	0	if (ctx == NULL) {
317	0	ctx = new_ctx = BN_CTX_new();
318	0	if (ctx == NULL)
319	0	return 0;
320	0	}
321	0
322	0	BN_CTX_start(ctx);
323	0	x = BN_CTX_get(ctx);
324	0	y = BN_CTX_get(ctx);
325	0	if (y == NULL)
326	0	goto err;
327	0
328	0	if (!BN_bin2bn(buf + 1, field_len, x))
329	0	goto err;
330	0	if (BN_ucmp(x, group->field) >= 0) {
331	0	ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
332	0	goto err;
333	0	}
334	0
335	0	if (form == POINT_CONVERSION_COMPRESSED) {
336	0	if (!EC_POINT_set_compressed_coordinates(group, point, x, y_bit, ctx))
337	0	goto err;
338	0	} else {
339	0	if (!BN_bin2bn(buf + 1 + field_len, field_len, y))
340	0	goto err;
341	0	if (BN_ucmp(y, group->field) >= 0) {
342	0	ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
343	0	goto err;
344	0	}
345	0	if (form == POINT_CONVERSION_HYBRID) {
346	0	if (y_bit != BN_is_odd(y)) {
347	0	ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
348	0	goto err;
349	0	}
350	0	}
351	0
352	0	/*
353	0	* EC_POINT_set_affine_coordinates is responsible for checking that
354	0	* the point is on the curve.
355	0	*/
356	0	if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
357	0	goto err;
358	0	}
359	0
360	0	ret = 1;
361	0
362	0	err:
363	0	BN_CTX_end(ctx);
364	0	BN_CTX_free(new_ctx);
365	0	return ret;
366	0	}