1 /* crypto/ec/ec2_oct.c */
2 /* ====================================================================
3 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
5 * The Elliptic Curve Public-Key Crypto Library (ECC Code) included
6 * herein is developed by SUN MICROSYSTEMS, INC., and is contributed
7 * to the OpenSSL project.
9 * The ECC Code is licensed pursuant to the OpenSSL open source
10 * license provided below.
12 * The software is originally written by Sheueling Chang Shantz and
13 * Douglas Stebila of Sun Microsystems Laboratories.
16 /* ====================================================================
17 * Copyright (c) 1998-2005 The OpenSSL Project. All rights reserved.
19 * Redistribution and use in source and binary forms, with or without
20 * modification, are permitted provided that the following conditions
23 * 1. Redistributions of source code must retain the above copyright
24 * notice, this list of conditions and the following disclaimer.
26 * 2. Redistributions in binary form must reproduce the above copyright
27 * notice, this list of conditions and the following disclaimer in
28 * the documentation and/or other materials provided with the
31 * 3. All advertising materials mentioning features or use of this
32 * software must display the following acknowledgment:
33 * "This product includes software developed by the OpenSSL Project
34 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
36 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
37 * endorse or promote products derived from this software without
38 * prior written permission. For written permission, please contact
39 * openssl-core@openssl.org.
41 * 5. Products derived from this software may not be called "OpenSSL"
42 * nor may "OpenSSL" appear in their names without prior written
43 * permission of the OpenSSL Project.
45 * 6. Redistributions of any form whatsoever must retain the following
47 * "This product includes software developed by the OpenSSL Project
48 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
50 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
51 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
52 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
53 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
54 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
55 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
56 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
57 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
58 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
59 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
60 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
61 * OF THE POSSIBILITY OF SUCH DAMAGE.
62 * ====================================================================
64 * This product includes cryptographic software written by Eric Young
65 * (eay@cryptsoft.com). This product includes software written by Tim
66 * Hudson (tjh@cryptsoft.com).
70 #include <openssl/err.h>
74 #ifndef OPENSSL_NO_EC2M
76 /* Calculates and sets the affine coordinates of an EC_POINT from the given
77 * compressed coordinates. Uses algorithm 2.3.4 of SEC 1.
78 * Note that the simple implementation only uses affine coordinates.
80 * The method is from the following publication:
82 * Harper, Menezes, Vanstone:
83 * "Public-Key Cryptosystems with Very Small Key Lengths",
84 * EUROCRYPT '92, Springer-Verlag LNCS 658,
85 * published February 1993
87 * US Patents 6,141,420 and 6,618,483 (Vanstone, Mullin, Agnew) describe
88 * the same method, but claim no priority date earlier than July 29, 1994
89 * (and additionally fail to cite the EUROCRYPT '92 publication as prior art).
91 int ec_GF2m_simple_set_compressed_coordinates(const EC_GROUP *group, EC_POINT *point,
92 const BIGNUM *x_, int y_bit, BN_CTX *ctx)
94 BN_CTX *new_ctx = NULL;
95 BIGNUM *tmp, *x, *y, *z;
98 /* clear error queue */
103 ctx = new_ctx = BN_CTX_new();
108 y_bit = (y_bit != 0) ? 1 : 0;
111 tmp = BN_CTX_get(ctx);
115 if (z == NULL) goto err;
117 if (!BN_GF2m_mod_arr(x, x_, group->poly)) goto err;
120 if (!BN_GF2m_mod_sqrt_arr(y, &group->b, group->poly, ctx)) goto err;
124 if (!group->meth->field_sqr(group, tmp, x, ctx)) goto err;
125 if (!group->meth->field_div(group, tmp, &group->b, tmp, ctx)) goto err;
126 if (!BN_GF2m_add(tmp, &group->a, tmp)) goto err;
127 if (!BN_GF2m_add(tmp, x, tmp)) goto err;
128 if (!BN_GF2m_mod_solve_quad_arr(z, tmp, group->poly, ctx))
130 unsigned long err = ERR_peek_last_error();
132 if (ERR_GET_LIB(err) == ERR_LIB_BN && ERR_GET_REASON(err) == BN_R_NO_SOLUTION)
135 ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, EC_R_INVALID_COMPRESSED_POINT);
138 ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, ERR_R_BN_LIB);
141 z0 = (BN_is_odd(z)) ? 1 : 0;
142 if (!group->meth->field_mul(group, y, x, z, ctx)) goto err;
145 if (!BN_GF2m_add(y, y, x)) goto err;
149 if (!EC_POINT_set_affine_coordinates_GF2m(group, point, x, y, ctx)) goto err;
156 BN_CTX_free(new_ctx);
161 /* Converts an EC_POINT to an octet string.
162 * If buf is NULL, the encoded length will be returned.
163 * If the length len of buf is smaller than required an error will be returned.
165 size_t ec_GF2m_simple_point2oct(const EC_GROUP *group, const EC_POINT *point, point_conversion_form_t form,
166 unsigned char *buf, size_t len, BN_CTX *ctx)
169 BN_CTX *new_ctx = NULL;
172 size_t field_len, i, skip;
174 if ((form != POINT_CONVERSION_COMPRESSED)
175 && (form != POINT_CONVERSION_UNCOMPRESSED)
176 && (form != POINT_CONVERSION_HYBRID))
178 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_INVALID_FORM);
182 if (EC_POINT_is_at_infinity(group, point))
184 /* encodes to a single 0 octet */
189 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
198 /* ret := required output buffer length */
199 field_len = (EC_GROUP_get_degree(group) + 7) / 8;
200 ret = (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2*field_len;
202 /* if 'buf' is NULL, just return required length */
207 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
213 ctx = new_ctx = BN_CTX_new();
222 yxi = BN_CTX_get(ctx);
223 if (yxi == NULL) goto err;
225 if (!EC_POINT_get_affine_coordinates_GF2m(group, point, x, y, ctx)) goto err;
228 if ((form != POINT_CONVERSION_UNCOMPRESSED) && !BN_is_zero(x))
230 if (!group->meth->field_div(group, yxi, y, x, ctx)) goto err;
231 if (BN_is_odd(yxi)) buf[0]++;
236 skip = field_len - BN_num_bytes(x);
237 if (skip > field_len)
239 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
247 skip = BN_bn2bin(x, buf + i);
249 if (i != 1 + field_len)
251 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
255 if (form == POINT_CONVERSION_UNCOMPRESSED || form == POINT_CONVERSION_HYBRID)
257 skip = field_len - BN_num_bytes(y);
258 if (skip > field_len)
260 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
268 skip = BN_bn2bin(y, buf + i);
274 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
282 BN_CTX_free(new_ctx);
289 BN_CTX_free(new_ctx);
294 /* Converts an octet string representation to an EC_POINT.
295 * Note that the simple implementation only uses affine coordinates.
297 int ec_GF2m_simple_oct2point(const EC_GROUP *group, EC_POINT *point,
298 const unsigned char *buf, size_t len, BN_CTX *ctx)
300 point_conversion_form_t form;
302 BN_CTX *new_ctx = NULL;
304 size_t field_len, enc_len;
309 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_BUFFER_TOO_SMALL);
315 if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED)
316 && (form != POINT_CONVERSION_UNCOMPRESSED)
317 && (form != POINT_CONVERSION_HYBRID))
319 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
322 if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit)
324 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
332 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
336 return EC_POINT_set_to_infinity(group, point);
339 field_len = (EC_GROUP_get_degree(group) + 7) / 8;
340 enc_len = (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2*field_len;
344 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
350 ctx = new_ctx = BN_CTX_new();
358 yxi = BN_CTX_get(ctx);
359 if (yxi == NULL) goto err;
361 if (!BN_bin2bn(buf + 1, field_len, x)) goto err;
362 if (BN_ucmp(x, &group->field) >= 0)
364 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
368 if (form == POINT_CONVERSION_COMPRESSED)
370 if (!EC_POINT_set_compressed_coordinates_GF2m(group, point, x, y_bit, ctx)) goto err;
374 if (!BN_bin2bn(buf + 1 + field_len, field_len, y)) goto err;
375 if (BN_ucmp(y, &group->field) >= 0)
377 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
380 if (form == POINT_CONVERSION_HYBRID)
382 if (!group->meth->field_div(group, yxi, y, x, ctx)) goto err;
383 if (y_bit != BN_is_odd(yxi))
385 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
390 if (!EC_POINT_set_affine_coordinates_GF2m(group, point, x, y, ctx)) goto err;
393 if (!EC_POINT_is_on_curve(group, point, ctx)) /* test required by X9.62 */
395 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_POINT_IS_NOT_ON_CURVE);
404 BN_CTX_free(new_ctx);