/* crypto/ec/ecp_oct.c */
/* 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 <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 cought 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_GFp(group, point, x, y, ctx)) goto err;
ret = 1;
err:
BN_CTX_end(ctx);
if (new_ctx != NULL)
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_GFp(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);
if (new_ctx != NULL)
BN_CTX_free(new_ctx);
return ret;
err:
if (used_ctx)
BN_CTX_end(ctx);
if (new_ctx != NULL)
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_GFp(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;
}
}
if (!EC_POINT_set_affine_coordinates_GFp(group, point, x, y, ctx)) goto err;
}
if (!EC_POINT_is_on_curve(group, point, ctx)) /* test required by X9.62 */
{
ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_POINT_IS_NOT_ON_CURVE);
goto err;
}
ret = 1;
err:
BN_CTX_end(ctx);
if (new_ctx != NULL)
BN_CTX_free(new_ctx);
return ret;
}