[thirdparty/openssl.git] / crypto / ec / ec2_oct.c

/*
 * Copyright 2011-2018 The OpenSSL Project Authors. All Rights Reserved.
 * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
 *
 * Licensed under the Apache License 2.0 (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_lcl.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)
{
    BIGNUM *tmp, *x, *y, *z;
    int ret = 0, z0;
#ifndef FIPS_MODE
    BN_CTX *new_ctx = NULL;

    /* clear error queue */
    ERR_clear_error();

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

    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)) {
#ifndef FIPS_MODE
            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
#endif
            {
                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);
#ifndef FIPS_MODE
    BN_CTX_free(new_ctx);
#endif
    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;
    int used_ctx = 0;
    BIGNUM *x, *y, *yxi;
    size_t field_len, i, skip;
#ifndef FIPS_MODE
    BN_CTX *new_ctx = NULL;
#endif

    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;
        }

#ifndef FIPS_MODE
        if (ctx == NULL) {
            ctx = new_ctx = BN_CTX_new();
            if (ctx == NULL)
                return 0;
        }
#endif

        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);
#ifndef FIPS_MODE
    BN_CTX_free(new_ctx);
#endif
    return ret;

 err:
    if (used_ctx)
        BN_CTX_end(ctx);
#ifndef FIPS_MODE
    BN_CTX_free(new_ctx);
#endif
    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;
    BIGNUM *x, *y, *yxi;
    size_t field_len, enc_len;
    int ret = 0;
#ifndef FIPS_MODE
    BN_CTX *new_ctx = NULL;
#endif

    if (len == 0) {
        ECerr(EC_F_EC_GF2M_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_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;
    }

    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;
    }

#ifndef FIPS_MODE
    if (ctx == NULL) {
        ctx = new_ctx = BN_CTX_new();
        if (ctx == NULL)
            return 0;
    }
#endif

    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) {
            if (!group->meth->field_div(group, yxi, y, x, ctx))
                goto err;
            if (y_bit != BN_is_odd(yxi)) {
                ECerr(EC_F_EC_GF2M_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);
#ifndef FIPS_MODE
    BN_CTX_free(new_ctx);
#endif
    return ret;
}
#endif
Commit	Line	Data
aa6bb135	1	/*
1212818e	2	* Copyright 2011-2018 The OpenSSL Project Authors. All Rights Reserved.
aa8f3d76	3	* Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
aa6bb135	4	*
a7f182b7	5	* Licensed under the Apache License 2.0 (the "License"). You may not use
aa6bb135 RS	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
84b08eee DSH	11	#include <openssl/err.h>
	12
	13	#include "ec_lcl.h"
	14
	15	#ifndef OPENSSL_NO_EC2M
	16
3a83462d MC	17	/*-
3a83462d MC	18	* Calculates and sets the affine coordinates of an EC_POINT from the given
0f113f3e	19	* compressed coordinates. Uses algorithm 2.3.4 of SEC 1.
84b08eee DSH	20	* Note that the simple implementation only uses affine coordinates.
	21	*
	22	* The method is from the following publication:
0f113f3e	23	*
84b08eee DSH	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	*/
0f113f3e MC	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	{
0f113f3e MC	38	BIGNUM tmp, x, y, z;
0f113f3e MC	39	int ret = 0, z0;
a9612d6c MC	40	#ifndef FIPS_MODE
a9612d6c MC	41	BN_CTX *new_ctx = NULL;
0f113f3e MC	42
	43	/* clear error queue */
	44	ERR_clear_error();
	45
	46	if (ctx == NULL) {
	47	ctx = new_ctx = BN_CTX_new();
	48	if (ctx == NULL)
	49	return 0;
	50	}
a9612d6c	51	#endif
0f113f3e MC	52
	53	y_bit = (y_bit != 0) ? 1 : 0;
	54
	55	BN_CTX_start(ctx);
	56	tmp = BN_CTX_get(ctx);
	57	x = BN_CTX_get(ctx);
	58	y = BN_CTX_get(ctx);
	59	z = BN_CTX_get(ctx);
	60	if (z == NULL)
	61	goto err;
	62
	63	if (!BN_GF2m_mod_arr(x, x_, group->poly))
	64	goto err;
	65	if (BN_is_zero(x)) {
	66	if (!BN_GF2m_mod_sqrt_arr(y, group->b, group->poly, ctx))
	67	goto err;
	68	} else {
	69	if (!group->meth->field_sqr(group, tmp, x, ctx))
	70	goto err;
	71	if (!group->meth->field_div(group, tmp, group->b, tmp, ctx))
	72	goto err;
	73	if (!BN_GF2m_add(tmp, group->a, tmp))
	74	goto err;
	75	if (!BN_GF2m_add(tmp, x, tmp))
	76	goto err;
	77	if (!BN_GF2m_mod_solve_quad_arr(z, tmp, group->poly, ctx)) {
a9612d6c	78	#ifndef FIPS_MODE
0f113f3e MC	79	unsigned long err = ERR_peek_last_error();
	80
	81	if (ERR_GET_LIB(err) == ERR_LIB_BN
	82	&& ERR_GET_REASON(err) == BN_R_NO_SOLUTION) {
	83	ERR_clear_error();
	84	ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES,
	85	EC_R_INVALID_COMPRESSED_POINT);
	86	} else
a9612d6c MC	87	#endif
a9612d6c MC	88	{
0f113f3e MC	89	ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES,
0f113f3e MC	90	ERR_R_BN_LIB);
a9612d6c	91	}
0f113f3e MC	92	goto err;
	93	}
	94	z0 = (BN_is_odd(z)) ? 1 : 0;
	95	if (!group->meth->field_mul(group, y, x, z, ctx))
	96	goto err;
	97	if (z0 != y_bit) {
	98	if (!BN_GF2m_add(y, y, x))
	99	goto err;
	100	}
	101	}
	102
9cc570d4	103	if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
0f113f3e MC	104	goto err;
	105
	106	ret = 1;
84b08eee DSH	107
84b08eee DSH	108	err:
0f113f3e	109	BN_CTX_end(ctx);
a9612d6c	110	#ifndef FIPS_MODE
23a1d5e9	111	BN_CTX_free(new_ctx);
a9612d6c	112	#endif
0f113f3e MC	113	return ret;
	114	}
	115
	116	/*
	117	* Converts an EC_POINT to an octet string. If buf is NULL, the encoded
	118	* length will be returned. If the length len of buf is smaller than required
	119	* an error will be returned.
84b08eee	120	*/
0f113f3e MC	121	size_t ec_GF2m_simple_point2oct(const EC_GROUP group, const EC_POINT point,
	122	point_conversion_form_t form,
	123	unsigned char buf, size_t len, BN_CTX ctx)
	124	{
	125	size_t ret;
0f113f3e MC	126	int used_ctx = 0;
	127	BIGNUM x, y, *yxi;
	128	size_t field_len, i, skip;
a9612d6c MC	129	#ifndef FIPS_MODE
	130	BN_CTX *new_ctx = NULL;
	131	#endif
0f113f3e MC	132
	133	if ((form != POINT_CONVERSION_COMPRESSED)
	134	&& (form != POINT_CONVERSION_UNCOMPRESSED)
	135	&& (form != POINT_CONVERSION_HYBRID)) {
	136	ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_INVALID_FORM);
	137	goto err;
	138	}
	139
	140	if (EC_POINT_is_at_infinity(group, point)) {
	141	/* encodes to a single 0 octet */
	142	if (buf != NULL) {
	143	if (len < 1) {
	144	ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
	145	return 0;
	146	}
	147	buf[0] = 0;
	148	}
	149	return 1;
	150	}
	151
	152	/* ret := required output buffer length */
	153	field_len = (EC_GROUP_get_degree(group) + 7) / 8;
	154	ret =
	155	(form ==
	156	POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
	157
	158	/* if 'buf' is NULL, just return required length */
	159	if (buf != NULL) {
	160	if (len < ret) {
	161	ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
	162	goto err;
	163	}
	164
a9612d6c	165	#ifndef FIPS_MODE
0f113f3e MC	166	if (ctx == NULL) {
	167	ctx = new_ctx = BN_CTX_new();
	168	if (ctx == NULL)
	169	return 0;
	170	}
a9612d6c	171	#endif
0f113f3e MC	172
	173	BN_CTX_start(ctx);
	174	used_ctx = 1;
	175	x = BN_CTX_get(ctx);
	176	y = BN_CTX_get(ctx);
	177	yxi = BN_CTX_get(ctx);
	178	if (yxi == NULL)
	179	goto err;
	180
9cc570d4	181	if (!EC_POINT_get_affine_coordinates(group, point, x, y, ctx))
0f113f3e MC	182	goto err;
	183
	184	buf[0] = form;
	185	if ((form != POINT_CONVERSION_UNCOMPRESSED) && !BN_is_zero(x)) {
	186	if (!group->meth->field_div(group, yxi, y, x, ctx))
	187	goto err;
	188	if (BN_is_odd(yxi))
	189	buf[0]++;
	190	}
	191
	192	i = 1;
	193
	194	skip = field_len - BN_num_bytes(x);
	195	if (skip > field_len) {
	196	ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
	197	goto err;
	198	}
	199	while (skip > 0) {
	200	buf[i++] = 0;
	201	skip--;
	202	}
	203	skip = BN_bn2bin(x, buf + i);
	204	i += skip;
	205	if (i != 1 + field_len) {
	206	ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
	207	goto err;
	208	}
	209
	210	if (form == POINT_CONVERSION_UNCOMPRESSED
	211	\|\| form == POINT_CONVERSION_HYBRID) {
	212	skip = field_len - BN_num_bytes(y);
	213	if (skip > field_len) {
	214	ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
	215	goto err;
	216	}
	217	while (skip > 0) {
	218	buf[i++] = 0;
	219	skip--;
	220	}
	221	skip = BN_bn2bin(y, buf + i);
	222	i += skip;
	223	}
	224
	225	if (i != ret) {
	226	ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
	227	goto err;
	228	}
	229	}
	230
	231	if (used_ctx)
	232	BN_CTX_end(ctx);
a9612d6c	233	#ifndef FIPS_MODE
23a1d5e9	234	BN_CTX_free(new_ctx);
a9612d6c	235	#endif
0f113f3e	236	return ret;
84b08eee DSH	237
84b08eee DSH	238	err:
0f113f3e MC	239	if (used_ctx)
0f113f3e MC	240	BN_CTX_end(ctx);
a9612d6c	241	#ifndef FIPS_MODE
23a1d5e9	242	BN_CTX_free(new_ctx);
a9612d6c	243	#endif
0f113f3e MC	244	return 0;
	245	}
	246
	247	/*
	248	* Converts an octet string representation to an EC_POINT. Note that the
	249	* simple implementation only uses affine coordinates.
84b08eee DSH	250	*/
84b08eee DSH	251	int ec_GF2m_simple_oct2point(const EC_GROUP group, EC_POINT point,
0f113f3e MC	252	const unsigned char *buf, size_t len,
	253	BN_CTX *ctx)
	254	{
	255	point_conversion_form_t form;
cad8347b	256	int y_bit, m;
0f113f3e MC	257	BIGNUM x, y, *yxi;
	258	size_t field_len, enc_len;
	259	int ret = 0;
a9612d6c MC	260	#ifndef FIPS_MODE
	261	BN_CTX *new_ctx = NULL;
	262	#endif
0f113f3e MC	263
	264	if (len == 0) {
	265	ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_BUFFER_TOO_SMALL);
	266	return 0;
	267	}
	268	form = buf[0];
	269	y_bit = form & 1;
	270	form = form & ~1U;
	271	if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED)
	272	&& (form != POINT_CONVERSION_UNCOMPRESSED)
	273	&& (form != POINT_CONVERSION_HYBRID)) {
	274	ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
	275	return 0;
	276	}
	277	if ((form == 0 \|\| form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) {
	278	ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
	279	return 0;
	280	}
	281
	282	if (form == 0) {
	283	if (len != 1) {
	284	ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
	285	return 0;
	286	}
	287
	288	return EC_POINT_set_to_infinity(group, point);
	289	}
	290
cad8347b SL	291	m = EC_GROUP_get_degree(group);
cad8347b SL	292	field_len = (m + 7) / 8;
0f113f3e MC	293	enc_len =
	294	(form ==
	295	POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
	296
	297	if (len != enc_len) {
	298	ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
	299	return 0;
	300	}
	301
a9612d6c	302	#ifndef FIPS_MODE
0f113f3e MC	303	if (ctx == NULL) {
	304	ctx = new_ctx = BN_CTX_new();
	305	if (ctx == NULL)
	306	return 0;
	307	}
a9612d6c	308	#endif
0f113f3e MC	309
	310	BN_CTX_start(ctx);
	311	x = BN_CTX_get(ctx);
	312	y = BN_CTX_get(ctx);
	313	yxi = BN_CTX_get(ctx);
	314	if (yxi == NULL)
	315	goto err;
	316
	317	if (!BN_bin2bn(buf + 1, field_len, x))
	318	goto err;
cad8347b	319	if (BN_num_bits(x) > m) {
0f113f3e MC	320	ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
	321	goto err;
	322	}
	323
	324	if (form == POINT_CONVERSION_COMPRESSED) {
9cc570d4	325	if (!EC_POINT_set_compressed_coordinates(group, point, x, y_bit, ctx))
0f113f3e MC	326	goto err;
	327	} else {
	328	if (!BN_bin2bn(buf + 1 + field_len, field_len, y))
	329	goto err;
cad8347b	330	if (BN_num_bits(y) > m) {
0f113f3e MC	331	ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
	332	goto err;
	333	}
	334	if (form == POINT_CONVERSION_HYBRID) {
	335	if (!group->meth->field_div(group, yxi, y, x, ctx))
	336	goto err;
	337	if (y_bit != BN_is_odd(yxi)) {
	338	ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
	339	goto err;
	340	}
	341	}
	342
1e2012b7	343	/*
9cc570d4	344	* EC_POINT_set_affine_coordinates is responsible for checking that
1e2012b7 EK	345	* the point is on the curve.
1e2012b7 EK	346	*/
9cc570d4	347	if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
0f113f3e MC	348	goto err;
	349	}
	350
0f113f3e MC	351	ret = 1;
0f113f3e MC	352
84b08eee	353	err:
0f113f3e	354	BN_CTX_end(ctx);
a9612d6c	355	#ifndef FIPS_MODE
23a1d5e9	356	BN_CTX_free(new_ctx);
a9612d6c	357	#endif
0f113f3e MC	358	return ret;
0f113f3e MC	359	}
84b08eee	360	#endif