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source: vbox/trunk/src/libs/openssl-1.1.1j/crypto/ec/ecp_oct.c@ 88461

Last change on this file since 88461 was 87984, checked in by vboxsync, 4 years ago

openssl-1.1.1j: Applied and adjusted our OpenSSL changes to 1.1.1j. bugref:9963
File size: 10.2 KB
Line 
1/*
2 * Copyright 2011-2018 The OpenSSL Project Authors. All Rights Reserved.
3 * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
4 *
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
9 */
10
11#include <openssl/err.h>
12#include <openssl/symhacks.h>
13
14#include "ec_local.h"
15
16int 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
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 */
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 + a*x */
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 /*
128 * BN_mod_sqrt() should have caught this error (not a square)
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
143 if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
144 goto err;
145
146 ret = 1;
147
148 err:
149 BN_CTX_end(ctx);
150 BN_CTX_free(new_ctx);
151 return ret;
152}
153
154size_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
209 if (!EC_POINT_get_affine_coordinates(group, point, x, y, ctx))
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);
259 BN_CTX_free(new_ctx);
260 return ret;
261
262 err:
263 if (used_ctx)
264 BN_CTX_end(ctx);
265 BN_CTX_free(new_ctx);
266 return 0;
267}
268
269int ec_GFp_simple_oct2point(const EC_GROUP *group, EC_POINT *point,
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) {
336 if (!EC_POINT_set_compressed_coordinates(group, point, x, y_bit, ctx))
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
352 /*
353 * EC_POINT_set_affine_coordinates is responsible for checking that
354 * the point is on the curve.
355 */
356 if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
357 goto err;
358 }
359
360 ret = 1;
361
362 err:
363 BN_CTX_end(ctx);
364 BN_CTX_free(new_ctx);
365 return ret;
366}
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