2 * Copyright 2011-2020 The OpenSSL Project Authors. All Rights Reserved.
3 * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
5 * Licensed under the Apache License 2.0 (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
12 * ECDSA low level APIs are deprecated for public use, but still ok for
15 #include "internal/deprecated.h"
17 #include <openssl/err.h>
18 #include <openssl/symhacks.h>
22 int ec_GFp_simple_set_compressed_coordinates(const EC_GROUP *group,
24 const BIGNUM *x_, int y_bit,
27 BN_CTX *new_ctx = NULL;
28 BIGNUM *tmp1, *tmp2, *x, *y;
32 /* clear error queue */
37 ctx = new_ctx = BN_CTX_new_ex(group->libctx);
45 tmp1 = BN_CTX_get(ctx);
46 tmp2 = BN_CTX_get(ctx);
53 * Recover y. We have a Weierstrass equation
54 * y^2 = x^3 + a*x + b,
55 * so y is one of the square roots of x^3 + a*x + b.
59 if (!BN_nnmod(x, x_, group->field, ctx))
61 if (group->meth->field_decode == 0) {
62 /* field_{sqr,mul} work on standard representation */
63 if (!group->meth->field_sqr(group, tmp2, x_, ctx))
65 if (!group->meth->field_mul(group, tmp1, tmp2, x_, ctx))
68 if (!BN_mod_sqr(tmp2, x_, group->field, ctx))
70 if (!BN_mod_mul(tmp1, tmp2, x_, group->field, ctx))
74 /* tmp1 := tmp1 + a*x */
75 if (group->a_is_minus3) {
76 if (!BN_mod_lshift1_quick(tmp2, x, group->field))
78 if (!BN_mod_add_quick(tmp2, tmp2, x, group->field))
80 if (!BN_mod_sub_quick(tmp1, tmp1, tmp2, group->field))
83 if (group->meth->field_decode) {
84 if (!group->meth->field_decode(group, tmp2, group->a, ctx))
86 if (!BN_mod_mul(tmp2, tmp2, x, group->field, ctx))
89 /* field_mul works on standard representation */
90 if (!group->meth->field_mul(group, tmp2, group->a, x, ctx))
94 if (!BN_mod_add_quick(tmp1, tmp1, tmp2, group->field))
98 /* tmp1 := tmp1 + b */
99 if (group->meth->field_decode) {
100 if (!group->meth->field_decode(group, tmp2, group->b, ctx))
102 if (!BN_mod_add_quick(tmp1, tmp1, tmp2, group->field))
105 if (!BN_mod_add_quick(tmp1, tmp1, group->b, group->field))
109 if (!BN_mod_sqrt(y, tmp1, group->field, ctx)) {
111 unsigned long err = ERR_peek_last_error();
113 if (ERR_GET_LIB(err) == ERR_LIB_BN
114 && ERR_GET_REASON(err) == BN_R_NOT_A_SQUARE) {
116 ERR_raise(ERR_LIB_EC, EC_R_INVALID_COMPRESSED_POINT);
120 ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
125 if (y_bit != BN_is_odd(y)) {
129 kron = BN_kronecker(x, group->field, ctx);
134 ERR_raise(ERR_LIB_EC, EC_R_INVALID_COMPRESSION_BIT);
137 * BN_mod_sqrt() should have caught this error (not a square)
139 ERR_raise(ERR_LIB_EC, EC_R_INVALID_COMPRESSED_POINT);
142 if (!BN_usub(y, group->field, y))
145 if (y_bit != BN_is_odd(y)) {
146 ERR_raise(ERR_LIB_EC, ERR_R_INTERNAL_ERROR);
150 if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
157 BN_CTX_free(new_ctx);
161 size_t ec_GFp_simple_point2oct(const EC_GROUP *group, const EC_POINT *point,
162 point_conversion_form_t form,
163 unsigned char *buf, size_t len, BN_CTX *ctx)
166 BN_CTX *new_ctx = NULL;
169 size_t field_len, i, skip;
171 if ((form != POINT_CONVERSION_COMPRESSED)
172 && (form != POINT_CONVERSION_UNCOMPRESSED)
173 && (form != POINT_CONVERSION_HYBRID)) {
174 ERR_raise(ERR_LIB_EC, EC_R_INVALID_FORM);
178 if (EC_POINT_is_at_infinity(group, point)) {
179 /* encodes to a single 0 octet */
182 ERR_raise(ERR_LIB_EC, EC_R_BUFFER_TOO_SMALL);
190 /* ret := required output buffer length */
191 field_len = BN_num_bytes(group->field);
194 POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
196 /* if 'buf' is NULL, just return required length */
199 ERR_raise(ERR_LIB_EC, EC_R_BUFFER_TOO_SMALL);
204 ctx = new_ctx = BN_CTX_new_ex(group->libctx);
216 if (!EC_POINT_get_affine_coordinates(group, point, x, y, ctx))
219 if ((form == POINT_CONVERSION_COMPRESSED
220 || form == POINT_CONVERSION_HYBRID) && BN_is_odd(y))
227 skip = field_len - BN_num_bytes(x);
228 if (skip > field_len) {
229 ERR_raise(ERR_LIB_EC, ERR_R_INTERNAL_ERROR);
236 skip = BN_bn2bin(x, buf + i);
238 if (i != 1 + field_len) {
239 ERR_raise(ERR_LIB_EC, ERR_R_INTERNAL_ERROR);
243 if (form == POINT_CONVERSION_UNCOMPRESSED
244 || form == POINT_CONVERSION_HYBRID) {
245 skip = field_len - BN_num_bytes(y);
246 if (skip > field_len) {
247 ERR_raise(ERR_LIB_EC, ERR_R_INTERNAL_ERROR);
254 skip = BN_bn2bin(y, buf + i);
259 ERR_raise(ERR_LIB_EC, ERR_R_INTERNAL_ERROR);
266 BN_CTX_free(new_ctx);
272 BN_CTX_free(new_ctx);
276 int ec_GFp_simple_oct2point(const EC_GROUP *group, EC_POINT *point,
277 const unsigned char *buf, size_t len, BN_CTX *ctx)
279 point_conversion_form_t form;
281 BN_CTX *new_ctx = NULL;
283 size_t field_len, enc_len;
287 ERR_raise(ERR_LIB_EC, EC_R_BUFFER_TOO_SMALL);
293 if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED)
294 && (form != POINT_CONVERSION_UNCOMPRESSED)
295 && (form != POINT_CONVERSION_HYBRID)) {
296 ERR_raise(ERR_LIB_EC, EC_R_INVALID_ENCODING);
299 if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) {
300 ERR_raise(ERR_LIB_EC, EC_R_INVALID_ENCODING);
306 ERR_raise(ERR_LIB_EC, EC_R_INVALID_ENCODING);
310 return EC_POINT_set_to_infinity(group, point);
313 field_len = BN_num_bytes(group->field);
316 POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
318 if (len != enc_len) {
319 ERR_raise(ERR_LIB_EC, EC_R_INVALID_ENCODING);
324 ctx = new_ctx = BN_CTX_new_ex(group->libctx);
335 if (!BN_bin2bn(buf + 1, field_len, x))
337 if (BN_ucmp(x, group->field) >= 0) {
338 ERR_raise(ERR_LIB_EC, EC_R_INVALID_ENCODING);
342 if (form == POINT_CONVERSION_COMPRESSED) {
343 if (!EC_POINT_set_compressed_coordinates(group, point, x, y_bit, ctx))
346 if (!BN_bin2bn(buf + 1 + field_len, field_len, y))
348 if (BN_ucmp(y, group->field) >= 0) {
349 ERR_raise(ERR_LIB_EC, EC_R_INVALID_ENCODING);
352 if (form == POINT_CONVERSION_HYBRID) {
353 if (y_bit != BN_is_odd(y)) {
354 ERR_raise(ERR_LIB_EC, EC_R_INVALID_ENCODING);
360 * EC_POINT_set_affine_coordinates is responsible for checking that
361 * the point is on the curve.
363 if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
371 BN_CTX_free(new_ctx);