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1/*
2 * Copyright 2002-2016 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/ec_key.h>
12
13#include <string.h>
14
15#include <openssl/ec.h>
16#include <openssl/ecdsa.h>
17#include <openssl/engine.h>
18#include <openssl/err.h>
19#include <openssl/ex_data.h>
20#include <openssl/mem.h>
21#include <openssl/thread.h>
22
23#include "../../internal.h"
24#include "../bcm_interface.h"
25#include "../delocate.h"
26#include "../ecdsa/internal.h"
27#include "../service_indicator/internal.h"
28#include "internal.h"
29
30
31DEFINE_STATIC_EX_DATA_CLASS(g_ec_ex_data_class)
32
33static EC_WRAPPED_SCALAR *ec_wrapped_scalar_new(const EC_GROUP *group) {
34  EC_WRAPPED_SCALAR *wrapped = reinterpret_cast<EC_WRAPPED_SCALAR *>(
35      OPENSSL_zalloc(sizeof(EC_WRAPPED_SCALAR)));
36  if (wrapped == NULL) {
37    return NULL;
38  }
39
40  wrapped->bignum.d = wrapped->scalar.words;
41  wrapped->bignum.width = group->order.N.width;
42  wrapped->bignum.dmax = group->order.N.width;
43  wrapped->bignum.flags = BN_FLG_STATIC_DATA;
44  return wrapped;
45}
46
47static void ec_wrapped_scalar_free(EC_WRAPPED_SCALAR *scalar) {
48  OPENSSL_free(scalar);
49}
50
51EC_KEY *EC_KEY_new(void) { return EC_KEY_new_method(NULL); }
52
53EC_KEY *EC_KEY_new_method(const ENGINE *engine) {
54  EC_KEY *ret = reinterpret_cast<EC_KEY *>(OPENSSL_zalloc(sizeof(EC_KEY)));
55  if (ret == NULL) {
56    return NULL;
57  }
58
59  if (engine) {
60    ret->ecdsa_meth = ENGINE_get_ECDSA_method(engine);
61  }
62  if (ret->ecdsa_meth) {
63    METHOD_ref(ret->ecdsa_meth);
64  }
65
66  ret->conv_form = POINT_CONVERSION_UNCOMPRESSED;
67  ret->references = 1;
68
69  CRYPTO_new_ex_data(&ret->ex_data);
70
71  if (ret->ecdsa_meth && ret->ecdsa_meth->init && !ret->ecdsa_meth->init(ret)) {
72    CRYPTO_free_ex_data(g_ec_ex_data_class_bss_get(), ret, &ret->ex_data);
73    if (ret->ecdsa_meth) {
74      METHOD_unref(ret->ecdsa_meth);
75    }
76    OPENSSL_free(ret);
77    return NULL;
78  }
79
80  return ret;
81}
82
83EC_KEY *EC_KEY_new_by_curve_name(int nid) {
84  EC_KEY *ret = EC_KEY_new();
85  if (ret == NULL) {
86    return NULL;
87  }
88  ret->group = EC_GROUP_new_by_curve_name(nid);
89  if (ret->group == NULL) {
90    EC_KEY_free(ret);
91    return NULL;
92  }
93  return ret;
94}
95
96void EC_KEY_free(EC_KEY *r) {
97  if (r == NULL) {
98    return;
99  }
100
101  if (!CRYPTO_refcount_dec_and_test_zero(&r->references)) {
102    return;
103  }
104
105  if (r->ecdsa_meth) {
106    if (r->ecdsa_meth->finish) {
107      r->ecdsa_meth->finish(r);
108    }
109    METHOD_unref(r->ecdsa_meth);
110  }
111
112  CRYPTO_free_ex_data(g_ec_ex_data_class_bss_get(), r, &r->ex_data);
113
114  EC_GROUP_free(r->group);
115  EC_POINT_free(r->pub_key);
116  ec_wrapped_scalar_free(r->priv_key);
117
118  OPENSSL_free(r);
119}
120
121EC_KEY *EC_KEY_dup(const EC_KEY *src) {
122  if (src == NULL) {
123    OPENSSL_PUT_ERROR(EC, ERR_R_PASSED_NULL_PARAMETER);
124    return NULL;
125  }
126
127  EC_KEY *ret = EC_KEY_new();
128  if (ret == NULL) {
129    return NULL;
130  }
131
132  if ((src->group != NULL && !EC_KEY_set_group(ret, src->group)) ||
133      (src->pub_key != NULL && !EC_KEY_set_public_key(ret, src->pub_key)) ||
134      (src->priv_key != NULL &&
135       !EC_KEY_set_private_key(ret, EC_KEY_get0_private_key(src)))) {
136    EC_KEY_free(ret);
137    return NULL;
138  }
139
140  ret->enc_flag = src->enc_flag;
141  ret->conv_form = src->conv_form;
142  return ret;
143}
144
145int EC_KEY_up_ref(EC_KEY *r) {
146  CRYPTO_refcount_inc(&r->references);
147  return 1;
148}
149
150int EC_KEY_is_opaque(const EC_KEY *key) {
151  return key->ecdsa_meth && (key->ecdsa_meth->flags & ECDSA_FLAG_OPAQUE);
152}
153
154const EC_GROUP *EC_KEY_get0_group(const EC_KEY *key) { return key->group; }
155
156int EC_KEY_set_group(EC_KEY *key, const EC_GROUP *group) {
157  // If |key| already has a group, it is an error to switch to another one.
158  if (key->group != NULL) {
159    if (EC_GROUP_cmp(key->group, group, NULL) != 0) {
160      OPENSSL_PUT_ERROR(EC, EC_R_GROUP_MISMATCH);
161      return 0;
162    }
163    return 1;
164  }
165
166  assert(key->priv_key == NULL);
167  assert(key->pub_key == NULL);
168
169  EC_GROUP_free(key->group);
170  key->group = EC_GROUP_dup(group);
171  return key->group != NULL;
172}
173
174const BIGNUM *EC_KEY_get0_private_key(const EC_KEY *key) {
175  return key->priv_key != NULL ? &key->priv_key->bignum : NULL;
176}
177
178int EC_KEY_set_private_key(EC_KEY *key, const BIGNUM *priv_key) {
179  if (key->group == NULL) {
180    OPENSSL_PUT_ERROR(EC, EC_R_MISSING_PARAMETERS);
181    return 0;
182  }
183
184  EC_WRAPPED_SCALAR *scalar = ec_wrapped_scalar_new(key->group);
185  if (scalar == NULL) {
186    return 0;
187  }
188  if (!ec_bignum_to_scalar(key->group, &scalar->scalar, priv_key) ||
189      // Zero is not a valid private key, so it is safe to leak the result of
190      // this comparison.
191      constant_time_declassify_int(
192          ec_scalar_is_zero(key->group, &scalar->scalar))) {
193    OPENSSL_PUT_ERROR(EC, EC_R_INVALID_PRIVATE_KEY);
194    ec_wrapped_scalar_free(scalar);
195    return 0;
196  }
197  ec_wrapped_scalar_free(key->priv_key);
198  key->priv_key = scalar;
199  return 1;
200}
201
202const EC_POINT *EC_KEY_get0_public_key(const EC_KEY *key) {
203  return key->pub_key;
204}
205
206int EC_KEY_set_public_key(EC_KEY *key, const EC_POINT *pub_key) {
207  if (key->group == NULL) {
208    OPENSSL_PUT_ERROR(EC, EC_R_MISSING_PARAMETERS);
209    return 0;
210  }
211
212  if (pub_key != NULL && EC_GROUP_cmp(key->group, pub_key->group, NULL) != 0) {
213    OPENSSL_PUT_ERROR(EC, EC_R_GROUP_MISMATCH);
214    return 0;
215  }
216
217  EC_POINT_free(key->pub_key);
218  key->pub_key = EC_POINT_dup(pub_key, key->group);
219  return (key->pub_key == NULL) ? 0 : 1;
220}
221
222unsigned int EC_KEY_get_enc_flags(const EC_KEY *key) { return key->enc_flag; }
223
224void EC_KEY_set_enc_flags(EC_KEY *key, unsigned int flags) {
225  key->enc_flag = flags;
226}
227
228point_conversion_form_t EC_KEY_get_conv_form(const EC_KEY *key) {
229  return key->conv_form;
230}
231
232void EC_KEY_set_conv_form(EC_KEY *key, point_conversion_form_t cform) {
233  key->conv_form = cform;
234}
235
236int EC_KEY_check_key(const EC_KEY *eckey) {
237  if (!eckey || !eckey->group || !eckey->pub_key) {
238    OPENSSL_PUT_ERROR(EC, ERR_R_PASSED_NULL_PARAMETER);
239    return 0;
240  }
241
242  if (EC_POINT_is_at_infinity(eckey->group, eckey->pub_key)) {
243    OPENSSL_PUT_ERROR(EC, EC_R_POINT_AT_INFINITY);
244    return 0;
245  }
246
247  // Test whether the public key is on the elliptic curve.
248  if (!EC_POINT_is_on_curve(eckey->group, eckey->pub_key, NULL)) {
249    OPENSSL_PUT_ERROR(EC, EC_R_POINT_IS_NOT_ON_CURVE);
250    return 0;
251  }
252
253  // Check the public and private keys match.
254  //
255  // NOTE: this is a FIPS pair-wise consistency check for the ECDH case. See SP
256  // 800-56Ar3, page 36.
257  if (eckey->priv_key != NULL) {
258    EC_JACOBIAN point;
259    if (!ec_point_mul_scalar_base(eckey->group, &point,
260                                  &eckey->priv_key->scalar)) {
261      OPENSSL_PUT_ERROR(EC, ERR_R_EC_LIB);
262      return 0;
263    }
264    // Leaking this comparison only leaks whether |eckey|'s public key was
265    // correct.
266    if (!constant_time_declassify_int(ec_GFp_simple_points_equal(
267            eckey->group, &point, &eckey->pub_key->raw))) {
268      OPENSSL_PUT_ERROR(EC, EC_R_INVALID_PRIVATE_KEY);
269      return 0;
270    }
271  }
272
273  return 1;
274}
275
276int EC_KEY_check_fips(const EC_KEY *key) {
277  int ret = 0;
278  FIPS_service_indicator_lock_state();
279
280  if (EC_KEY_is_opaque(key)) {
281    // Opaque keys can't be checked.
282    OPENSSL_PUT_ERROR(EC, EC_R_PUBLIC_KEY_VALIDATION_FAILED);
283    goto end;
284  }
285
286  if (!EC_KEY_check_key(key)) {
287    goto end;
288  }
289
290  if (key->priv_key) {
291    uint8_t digest[BCM_SHA256_DIGEST_LENGTH] = {0};
292    uint8_t sig[ECDSA_MAX_FIXED_LEN];
293    size_t sig_len;
294    if (!ecdsa_sign_fixed(digest, sizeof(digest), sig, &sig_len, sizeof(sig),
295                          key)) {
296      goto end;
297    }
298    if (boringssl_fips_break_test("ECDSA_PWCT")) {
299      digest[0] = ~digest[0];
300    }
301    if (!ecdsa_verify_fixed(digest, sizeof(digest), sig, sig_len, key)) {
302      OPENSSL_PUT_ERROR(EC, EC_R_PUBLIC_KEY_VALIDATION_FAILED);
303      goto end;
304    }
305  }
306
307  ret = 1;
308
309end:
310  FIPS_service_indicator_unlock_state();
311  if (ret) {
312    EC_KEY_keygen_verify_service_indicator(key);
313  }
314
315  return ret;
316}
317
318int EC_KEY_set_public_key_affine_coordinates(EC_KEY *key, const BIGNUM *x,
319                                             const BIGNUM *y) {
320  EC_POINT *point = NULL;
321  int ok = 0;
322
323  if (!key || !key->group || !x || !y) {
324    OPENSSL_PUT_ERROR(EC, ERR_R_PASSED_NULL_PARAMETER);
325    return 0;
326  }
327
328  point = EC_POINT_new(key->group);
329  if (point == NULL ||
330      !EC_POINT_set_affine_coordinates_GFp(key->group, point, x, y, NULL) ||
331      !EC_KEY_set_public_key(key, point) || !EC_KEY_check_key(key)) {
332    goto err;
333  }
334
335  ok = 1;
336
337err:
338  EC_POINT_free(point);
339  return ok;
340}
341
342int EC_KEY_oct2key(EC_KEY *key, const uint8_t *in, size_t len, BN_CTX *ctx) {
343  if (key->group == NULL) {
344    OPENSSL_PUT_ERROR(EC, EC_R_MISSING_PARAMETERS);
345    return 0;
346  }
347
348  EC_POINT *point = EC_POINT_new(key->group);
349  int ok = point != NULL &&
350           EC_POINT_oct2point(key->group, point, in, len, ctx) &&
351           EC_KEY_set_public_key(key, point);
352  EC_POINT_free(point);
353  return ok;
354}
355
356size_t EC_KEY_key2buf(const EC_KEY *key, point_conversion_form_t form,
357                      uint8_t **out_buf, BN_CTX *ctx) {
358  if (key == NULL || key->pub_key == NULL || key->group == NULL) {
359    OPENSSL_PUT_ERROR(EC, EC_R_MISSING_PARAMETERS);
360    return 0;
361  }
362
363  return EC_POINT_point2buf(key->group, key->pub_key, form, out_buf, ctx);
364}
365
366int EC_KEY_oct2priv(EC_KEY *key, const uint8_t *in, size_t len) {
367  if (key->group == NULL) {
368    OPENSSL_PUT_ERROR(EC, EC_R_MISSING_PARAMETERS);
369    return 0;
370  }
371
372  if (len != BN_num_bytes(EC_GROUP_get0_order(key->group))) {
373    OPENSSL_PUT_ERROR(EC, EC_R_DECODE_ERROR);
374    return 0;
375  }
376
377  BIGNUM *priv_key = BN_bin2bn(in, len, NULL);
378  int ok = priv_key != NULL &&  //
379           EC_KEY_set_private_key(key, priv_key);
380  BN_free(priv_key);
381  return ok;
382}
383
384size_t EC_KEY_priv2oct(const EC_KEY *key, uint8_t *out, size_t max_out) {
385  if (key->group == NULL || key->priv_key == NULL) {
386    OPENSSL_PUT_ERROR(EC, EC_R_MISSING_PARAMETERS);
387    return 0;
388  }
389
390  size_t len = BN_num_bytes(EC_GROUP_get0_order(key->group));
391  if (out == NULL) {
392    return len;
393  }
394
395  if (max_out < len) {
396    OPENSSL_PUT_ERROR(EC, EC_R_BUFFER_TOO_SMALL);
397    return 0;
398  }
399
400  size_t bytes_written;
401  ec_scalar_to_bytes(key->group, out, &bytes_written, &key->priv_key->scalar);
402  assert(bytes_written == len);
403  return len;
404}
405
406size_t EC_KEY_priv2buf(const EC_KEY *key, uint8_t **out_buf) {
407  *out_buf = NULL;
408  size_t len = EC_KEY_priv2oct(key, NULL, 0);
409  if (len == 0) {
410    return 0;
411  }
412
413  uint8_t *buf = reinterpret_cast<uint8_t *>(OPENSSL_malloc(len));
414  if (buf == NULL) {
415    return 0;
416  }
417
418  len = EC_KEY_priv2oct(key, buf, len);
419  if (len == 0) {
420    OPENSSL_free(buf);
421    return 0;
422  }
423
424  *out_buf = buf;
425  return len;
426}
427
428int EC_KEY_generate_key(EC_KEY *key) {
429  if (key == NULL || key->group == NULL) {
430    OPENSSL_PUT_ERROR(EC, ERR_R_PASSED_NULL_PARAMETER);
431    return 0;
432  }
433
434  // Check that the group order is FIPS compliant (FIPS 186-4 B.4.2).
435  if (EC_GROUP_order_bits(key->group) < 160) {
436    OPENSSL_PUT_ERROR(EC, EC_R_INVALID_GROUP_ORDER);
437    return 0;
438  }
439
440  static const uint8_t kDefaultAdditionalData[32] = {0};
441  EC_WRAPPED_SCALAR *priv_key = ec_wrapped_scalar_new(key->group);
442  EC_POINT *pub_key = EC_POINT_new(key->group);
443  if (priv_key == NULL || pub_key == NULL ||
444      // Generate the private key by testing candidates (FIPS 186-4 B.4.2).
445      !ec_random_nonzero_scalar(key->group, &priv_key->scalar,
446                                kDefaultAdditionalData) ||
447      !ec_point_mul_scalar_base(key->group, &pub_key->raw, &priv_key->scalar)) {
448    EC_POINT_free(pub_key);
449    ec_wrapped_scalar_free(priv_key);
450    return 0;
451  }
452
453  // The public key is derived from the private key, but it is public.
454  //
455  // TODO(crbug.com/boringssl/677): This isn't quite right. While |pub_key|
456  // represents a public point, it is still in Jacobian form and the exact
457  // Jacobian representation is secret. We need to make it affine first. See
458  // discussion in the bug.
459  CONSTTIME_DECLASSIFY(&pub_key->raw, sizeof(pub_key->raw));
460
461  ec_wrapped_scalar_free(key->priv_key);
462  key->priv_key = priv_key;
463  EC_POINT_free(key->pub_key);
464  key->pub_key = pub_key;
465  return 1;
466}
467
468int EC_KEY_generate_key_fips(EC_KEY *eckey) {
469  if (eckey == NULL || eckey->group == NULL) {
470    OPENSSL_PUT_ERROR(EC, ERR_R_PASSED_NULL_PARAMETER);
471    return 0;
472  }
473
474  boringssl_ensure_ecc_self_test();
475
476  if (EC_KEY_generate_key(eckey) && EC_KEY_check_fips(eckey)) {
477    return 1;
478  }
479
480  EC_POINT_free(eckey->pub_key);
481  ec_wrapped_scalar_free(eckey->priv_key);
482  eckey->pub_key = NULL;
483  eckey->priv_key = NULL;
484  return 0;
485}
486
487int EC_KEY_get_ex_new_index(long argl, void *argp, CRYPTO_EX_unused *unused,
488                            CRYPTO_EX_dup *dup_unused,
489                            CRYPTO_EX_free *free_func) {
490  return CRYPTO_get_ex_new_index_ex(g_ec_ex_data_class_bss_get(), argl, argp,
491                                    free_func);
492}
493
494int EC_KEY_set_ex_data(EC_KEY *d, int idx, void *arg) {
495  return CRYPTO_set_ex_data(&d->ex_data, idx, arg);
496}
497
498void *EC_KEY_get_ex_data(const EC_KEY *d, int idx) {
499  return CRYPTO_get_ex_data(&d->ex_data, idx);
500}
501
502void EC_KEY_set_asn1_flag(EC_KEY *key, int flag) {}
503