2 * Copyright 2011-2016 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the OpenSSL license (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
10 /* ====================================================================
11 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
12 * Portions of this software developed by SUN MICROSYSTEMS, INC.,
13 * and contributed to the OpenSSL project.
16 #include <openssl/err.h>
17 #include <openssl/symhacks.h>
21 int ec_GFp_simple_set_compressed_coordinates(const EC_GROUP *group,
23 const BIGNUM *x_, int y_bit,
26 BN_CTX *new_ctx = NULL;
27 BIGNUM *tmp1, *tmp2, *x, *y;
30 /* clear error queue */
34 ctx = new_ctx = BN_CTX_new();
42 tmp1 = BN_CTX_get(ctx);
43 tmp2 = BN_CTX_get(ctx);
50 * Recover y. We have a Weierstrass equation
51 * y^2 = x^3 + a*x + b,
52 * so y is one of the square roots of x^3 + a*x + b.
56 if (!BN_nnmod(x, x_, group->field, ctx))
58 if (group->meth->field_decode == 0) {
59 /* field_{sqr,mul} work on standard representation */
60 if (!group->meth->field_sqr(group, tmp2, x_, ctx))
62 if (!group->meth->field_mul(group, tmp1, tmp2, x_, ctx))
65 if (!BN_mod_sqr(tmp2, x_, group->field, ctx))
67 if (!BN_mod_mul(tmp1, tmp2, x_, group->field, ctx))
71 /* tmp1 := tmp1 + a*x */
72 if (group->a_is_minus3) {
73 if (!BN_mod_lshift1_quick(tmp2, x, group->field))
75 if (!BN_mod_add_quick(tmp2, tmp2, x, group->field))
77 if (!BN_mod_sub_quick(tmp1, tmp1, tmp2, group->field))
80 if (group->meth->field_decode) {
81 if (!group->meth->field_decode(group, tmp2, group->a, ctx))
83 if (!BN_mod_mul(tmp2, tmp2, x, group->field, ctx))
86 /* field_mul works on standard representation */
87 if (!group->meth->field_mul(group, tmp2, group->a, x, ctx))
91 if (!BN_mod_add_quick(tmp1, tmp1, tmp2, group->field))
95 /* tmp1 := tmp1 + b */
96 if (group->meth->field_decode) {
97 if (!group->meth->field_decode(group, tmp2, group->b, ctx))
99 if (!BN_mod_add_quick(tmp1, tmp1, tmp2, group->field))
102 if (!BN_mod_add_quick(tmp1, tmp1, group->b, group->field))
106 if (!BN_mod_sqrt(y, tmp1, group->field, ctx)) {
107 unsigned long err = ERR_peek_last_error();
109 if (ERR_GET_LIB(err) == ERR_LIB_BN
110 && ERR_GET_REASON(err) == BN_R_NOT_A_SQUARE) {
112 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
113 EC_R_INVALID_COMPRESSED_POINT);
115 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
120 if (y_bit != BN_is_odd(y)) {
124 kron = BN_kronecker(x, group->field, ctx);
129 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
130 EC_R_INVALID_COMPRESSION_BIT);
133 * BN_mod_sqrt() should have cought this error (not a square)
135 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
136 EC_R_INVALID_COMPRESSED_POINT);
139 if (!BN_usub(y, group->field, y))
142 if (y_bit != BN_is_odd(y)) {
143 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
144 ERR_R_INTERNAL_ERROR);
148 if (!EC_POINT_set_affine_coordinates_GFp(group, point, x, y, ctx))
155 BN_CTX_free(new_ctx);
159 size_t ec_GFp_simple_point2oct(const EC_GROUP *group, const EC_POINT *point,
160 point_conversion_form_t form,
161 unsigned char *buf, size_t len, BN_CTX *ctx)
164 BN_CTX *new_ctx = NULL;
167 size_t field_len, i, skip;
169 if ((form != POINT_CONVERSION_COMPRESSED)
170 && (form != POINT_CONVERSION_UNCOMPRESSED)
171 && (form != POINT_CONVERSION_HYBRID)) {
172 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_INVALID_FORM);
176 if (EC_POINT_is_at_infinity(group, point)) {
177 /* encodes to a single 0 octet */
180 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
188 /* ret := required output buffer length */
189 field_len = BN_num_bytes(group->field);
192 POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
194 /* if 'buf' is NULL, just return required length */
197 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
202 ctx = new_ctx = BN_CTX_new();
214 if (!EC_POINT_get_affine_coordinates_GFp(group, point, x, y, ctx))
217 if ((form == POINT_CONVERSION_COMPRESSED
218 || form == POINT_CONVERSION_HYBRID) && BN_is_odd(y))
225 skip = field_len - BN_num_bytes(x);
226 if (skip > field_len) {
227 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
234 skip = BN_bn2bin(x, buf + i);
236 if (i != 1 + field_len) {
237 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
241 if (form == POINT_CONVERSION_UNCOMPRESSED
242 || form == POINT_CONVERSION_HYBRID) {
243 skip = field_len - BN_num_bytes(y);
244 if (skip > field_len) {
245 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
252 skip = BN_bn2bin(y, buf + i);
257 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
264 BN_CTX_free(new_ctx);
270 BN_CTX_free(new_ctx);
274 int ec_GFp_simple_oct2point(const EC_GROUP *group, EC_POINT *point,
275 const unsigned char *buf, size_t len, BN_CTX *ctx)
277 point_conversion_form_t form;
279 BN_CTX *new_ctx = NULL;
281 size_t field_len, enc_len;
285 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_BUFFER_TOO_SMALL);
291 if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED)
292 && (form != POINT_CONVERSION_UNCOMPRESSED)
293 && (form != POINT_CONVERSION_HYBRID)) {
294 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
297 if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) {
298 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
304 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
308 return EC_POINT_set_to_infinity(group, point);
311 field_len = BN_num_bytes(group->field);
314 POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
316 if (len != enc_len) {
317 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
322 ctx = new_ctx = BN_CTX_new();
333 if (!BN_bin2bn(buf + 1, field_len, x))
335 if (BN_ucmp(x, group->field) >= 0) {
336 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
340 if (form == POINT_CONVERSION_COMPRESSED) {
341 if (!EC_POINT_set_compressed_coordinates_GFp
342 (group, point, x, y_bit, ctx))
345 if (!BN_bin2bn(buf + 1 + field_len, field_len, y))
347 if (BN_ucmp(y, group->field) >= 0) {
348 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
351 if (form == POINT_CONVERSION_HYBRID) {
352 if (y_bit != BN_is_odd(y)) {
353 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
359 * EC_POINT_set_affine_coordinates_GFp is responsible for checking that
360 * the point is on the curve.
362 if (!EC_POINT_set_affine_coordinates_GFp(group, point, x, y, ctx))
370 BN_CTX_free(new_ctx);