[thirdparty/openssl.git] / crypto / ec / ecp_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 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_local.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;
}
Commit	Line	Data
0f113f3e	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
84b08eee	4	*
4f22f405 RS	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
84b08eee	9	*/
4f22f405	10
84b08eee DSH	11	#include <openssl/err.h>
	12	#include <openssl/symhacks.h>
	13
b5acbf91	14	#include "ec_local.h"
84b08eee	15
0f113f3e MC	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	{
	21	BN_CTX *new_ctx = NULL;
	22	BIGNUM tmp1, tmp2, x, y;
	23	int ret = 0;
	24
	25	/* clear error queue */
	26	ERR_clear_error();
	27
	28	if (ctx == NULL) {
	29	ctx = new_ctx = BN_CTX_new();
	30	if (ctx == NULL)
	31	return 0;
	32	}
	33
	34	y_bit = (y_bit != 0);
	35
	36	BN_CTX_start(ctx);
	37	tmp1 = BN_CTX_get(ctx);
	38	tmp2 = BN_CTX_get(ctx);
	39	x = BN_CTX_get(ctx);
	40	y = BN_CTX_get(ctx);
	41	if (y == NULL)
	42	goto err;
	43
35a1cc90 MC	44	/*-
	45	* Recover y. We have a Weierstrass equation
	46	* y^2 = x^3 + a*x + b,
	47	* so y is one of the square roots of x^3 + a*x + b.
	48	*/
0f113f3e MC	49
	50	/* tmp1 := x^3 */
	51	if (!BN_nnmod(x, x_, group->field, ctx))
	52	goto err;
	53	if (group->meth->field_decode == 0) {
	54	/* field_{sqr,mul} work on standard representation */
	55	if (!group->meth->field_sqr(group, tmp2, x_, ctx))
	56	goto err;
	57	if (!group->meth->field_mul(group, tmp1, tmp2, x_, ctx))
	58	goto err;
	59	} else {
	60	if (!BN_mod_sqr(tmp2, x_, group->field, ctx))
	61	goto err;
	62	if (!BN_mod_mul(tmp1, tmp2, x_, group->field, ctx))
	63	goto err;
	64	}
	65
	66	/* tmp1 := tmp1 + ax /
	67	if (group->a_is_minus3) {
	68	if (!BN_mod_lshift1_quick(tmp2, x, group->field))
	69	goto err;
	70	if (!BN_mod_add_quick(tmp2, tmp2, x, group->field))
	71	goto err;
	72	if (!BN_mod_sub_quick(tmp1, tmp1, tmp2, group->field))
	73	goto err;
	74	} else {
	75	if (group->meth->field_decode) {
	76	if (!group->meth->field_decode(group, tmp2, group->a, ctx))
	77	goto err;
	78	if (!BN_mod_mul(tmp2, tmp2, x, group->field, ctx))
	79	goto err;
	80	} else {
	81	/* field_mul works on standard representation */
	82	if (!group->meth->field_mul(group, tmp2, group->a, x, ctx))
	83	goto err;
	84	}
	85
	86	if (!BN_mod_add_quick(tmp1, tmp1, tmp2, group->field))
	87	goto err;
	88	}
	89
	90	/* tmp1 := tmp1 + b */
	91	if (group->meth->field_decode) {
	92	if (!group->meth->field_decode(group, tmp2, group->b, ctx))
	93	goto err;
	94	if (!BN_mod_add_quick(tmp1, tmp1, tmp2, group->field))
	95	goto err;
	96	} else {
	97	if (!BN_mod_add_quick(tmp1, tmp1, group->b, group->field))
	98	goto err;
	99	}
	100
	101	if (!BN_mod_sqrt(y, tmp1, group->field, ctx)) {
	102	unsigned long err = ERR_peek_last_error();
	103
	104	if (ERR_GET_LIB(err) == ERR_LIB_BN
	105	&& ERR_GET_REASON(err) == BN_R_NOT_A_SQUARE) {
	106	ERR_clear_error();
	107	ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
	108	EC_R_INVALID_COMPRESSED_POINT);
	109	} else
	110	ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
	111	ERR_R_BN_LIB);
	112	goto err;
113	}
114
115	if (y_bit != BN_is_odd(y)) {
116	if (BN_is_zero(y)) {
117	int kron;
118
119	kron = BN_kronecker(x, group->field, ctx);
120	if (kron == -2)
121	goto err;
122
123	if (kron == 1)
124	ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
125	EC_R_INVALID_COMPRESSION_BIT);
126	else
127	/*
46f4e1be	128	* BN_mod_sqrt() should have caught this error (not a square)
0f113f3e MC	129	*/
	130	ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
	131	EC_R_INVALID_COMPRESSED_POINT);
	132	goto err;
	133	}
	134	if (!BN_usub(y, group->field, y))
	135	goto err;
	136	}
	137	if (y_bit != BN_is_odd(y)) {
	138	ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
	139	ERR_R_INTERNAL_ERROR);
	140	goto err;
	141	}
	142
9cc570d4	143	if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
0f113f3e MC	144	goto err;
	145
	146	ret = 1;
84b08eee DSH	147
84b08eee DSH	148	err:
0f113f3e	149	BN_CTX_end(ctx);
23a1d5e9	150	BN_CTX_free(new_ctx);
0f113f3e MC	151	return ret;
	152	}
	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	{
	158	size_t ret;
	159	BN_CTX *new_ctx = NULL;
	160	int used_ctx = 0;
	161	BIGNUM x, y;
	162	size_t field_len, i, skip;
	163
	164	if ((form != POINT_CONVERSION_COMPRESSED)
	165	&& (form != POINT_CONVERSION_UNCOMPRESSED)
	166	&& (form != POINT_CONVERSION_HYBRID)) {
	167	ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_INVALID_FORM);
	168	goto err;
	169	}
	170
	171	if (EC_POINT_is_at_infinity(group, point)) {
	172	/* encodes to a single 0 octet */
	173	if (buf != NULL) {
	174	if (len < 1) {
	175	ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
	176	return 0;
	177	}
	178	buf[0] = 0;
	179	}
	180	return 1;
	181	}
	182
	183	/* ret := required output buffer length */
	184	field_len = BN_num_bytes(group->field);
	185	ret =
	186	(form ==
	187	POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
	188
	189	/* if 'buf' is NULL, just return required length */
	190	if (buf != NULL) {
	191	if (len < ret) {
	192	ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
	193	goto err;
	194	}
	195
	196	if (ctx == NULL) {
	197	ctx = new_ctx = BN_CTX_new();
	198	if (ctx == NULL)
	199	return 0;
	200	}
	201
	202	BN_CTX_start(ctx);
	203	used_ctx = 1;
	204	x = BN_CTX_get(ctx);
	205	y = BN_CTX_get(ctx);
	206	if (y == NULL)
	207	goto err;
	208
9cc570d4	209	if (!EC_POINT_get_affine_coordinates(group, point, x, y, ctx))
0f113f3e MC	210	goto err;
	211
	212	if ((form == POINT_CONVERSION_COMPRESSED
	213	\|\| form == POINT_CONVERSION_HYBRID) && BN_is_odd(y))
	214	buf[0] = form + 1;
	215	else
	216	buf[0] = form;
	217
	218	i = 1;
	219
	220	skip = field_len - BN_num_bytes(x);
	221	if (skip > field_len) {
	222	ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
	223	goto err;
	224	}
	225	while (skip > 0) {
	226	buf[i++] = 0;
	227	skip--;
	228	}
	229	skip = BN_bn2bin(x, buf + i);
	230	i += skip;
	231	if (i != 1 + field_len) {
	232	ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
	233	goto err;
	234	}
	235
	236	if (form == POINT_CONVERSION_UNCOMPRESSED
	237	\|\| form == POINT_CONVERSION_HYBRID) {
	238	skip = field_len - BN_num_bytes(y);
	239	if (skip > field_len) {
	240	ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
	241	goto err;
	242	}
	243	while (skip > 0) {
	244	buf[i++] = 0;
	245	skip--;
	246	}
	247	skip = BN_bn2bin(y, buf + i);
	248	i += skip;
	249	}
	250
	251	if (i != ret) {
	252	ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
	253	goto err;
	254	}
	255	}
	256
	257	if (used_ctx)
	258	BN_CTX_end(ctx);
23a1d5e9	259	BN_CTX_free(new_ctx);
0f113f3e	260	return ret;
84b08eee DSH	261
84b08eee DSH	262	err:
0f113f3e MC	263	if (used_ctx)
0f113f3e MC	264	BN_CTX_end(ctx);
23a1d5e9	265	BN_CTX_free(new_ctx);
0f113f3e MC	266	return 0;
0f113f3e MC	267	}
84b08eee DSH	268
84b08eee DSH	269	int ec_GFp_simple_oct2point(const EC_GROUP group, EC_POINT point,
0f113f3e MC	270	const unsigned char buf, size_t len, BN_CTX ctx)
	271	{
	272	point_conversion_form_t form;
	273	int y_bit;
	274	BN_CTX *new_ctx = NULL;
	275	BIGNUM x, y;
	276	size_t field_len, enc_len;
	277	int ret = 0;
	278
	279	if (len == 0) {
	280	ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_BUFFER_TOO_SMALL);
	281	return 0;
	282	}
	283	form = buf[0];
	284	y_bit = form & 1;
	285	form = form & ~1U;
	286	if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED)
	287	&& (form != POINT_CONVERSION_UNCOMPRESSED)
	288	&& (form != POINT_CONVERSION_HYBRID)) {
	289	ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
	290	return 0;
	291	}
	292	if ((form == 0 \|\| form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) {
	293	ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
	294	return 0;
	295	}
	296
	297	if (form == 0) {
	298	if (len != 1) {
	299	ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
	300	return 0;
	301	}
	302
	303	return EC_POINT_set_to_infinity(group, point);
	304	}
	305
	306	field_len = BN_num_bytes(group->field);
	307	enc_len =
	308	(form ==
	309	POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
	310
	311	if (len != enc_len) {
	312	ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
	313	return 0;
	314	}
	315
	316	if (ctx == NULL) {
	317	ctx = new_ctx = BN_CTX_new();
	318	if (ctx == NULL)
	319	return 0;
	320	}
	321
	322	BN_CTX_start(ctx);
	323	x = BN_CTX_get(ctx);
	324	y = BN_CTX_get(ctx);
	325	if (y == NULL)
	326	goto err;
	327
	328	if (!BN_bin2bn(buf + 1, field_len, x))
	329	goto err;
	330	if (BN_ucmp(x, group->field) >= 0) {
	331	ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
	332	goto err;
	333	}
334
335	if (form == POINT_CONVERSION_COMPRESSED) {
9cc570d4	336	if (!EC_POINT_set_compressed_coordinates(group, point, x, y_bit, ctx))
0f113f3e MC	337	goto err;
	338	} else {
	339	if (!BN_bin2bn(buf + 1 + field_len, field_len, y))
	340	goto err;
	341	if (BN_ucmp(y, group->field) >= 0) {
	342	ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
	343	goto err;
	344	}
	345	if (form == POINT_CONVERSION_HYBRID) {
	346	if (y_bit != BN_is_odd(y)) {
	347	ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
	348	goto err;
	349	}
	350	}
	351
1e2012b7	352	/*
9cc570d4	353	* EC_POINT_set_affine_coordinates is responsible for checking that
1e2012b7 EK	354	* the point is on the curve.
1e2012b7 EK	355	*/
9cc570d4	356	if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
0f113f3e MC	357	goto err;
	358	}
	359
0f113f3e	360	ret = 1;
84b08eee	361
0f113f3e MC	362	err:
0f113f3e MC	363	BN_CTX_end(ctx);
23a1d5e9	364	BN_CTX_free(new_ctx);
0f113f3e MC	365	return ret;
0f113f3e MC	366	}