1 /* Copyright (c) 2016, Google Inc.
2 *
3 * Permission to use, copy, modify, and/or distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
6 *
7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
14
15 #include <openssl/ssl.h>
16
17 #include <assert.h>
18 #include <string.h>
19
20 #include <algorithm>
21 #include <utility>
22
23 #include <openssl/aead.h>
24 #include <openssl/bytestring.h>
25 #include <openssl/digest.h>
26 #include <openssl/hkdf.h>
27 #include <openssl/hmac.h>
28 #include <openssl/mem.h>
29
30 #include "../crypto/internal.h"
31 #include "internal.h"
32
33
34 BSSL_NAMESPACE_BEGIN
35
init_key_schedule(SSL_HANDSHAKE * hs,uint16_t version,const SSL_CIPHER * cipher)36 static bool init_key_schedule(SSL_HANDSHAKE *hs, uint16_t version,
37 const SSL_CIPHER *cipher) {
38 if (!hs->transcript.InitHash(version, cipher)) {
39 return false;
40 }
41
42 // Initialize the secret to the zero key.
43 hs->ResizeSecrets(hs->transcript.DigestLen());
44 OPENSSL_memset(hs->secret().data(), 0, hs->secret().size());
45
46 return true;
47 }
48
hkdf_extract_to_secret(SSL_HANDSHAKE * hs,Span<const uint8_t> in)49 static bool hkdf_extract_to_secret(SSL_HANDSHAKE *hs, Span<const uint8_t> in) {
50 size_t len;
51 if (!HKDF_extract(hs->secret().data(), &len, hs->transcript.Digest(),
52 in.data(), in.size(), hs->secret().data(),
53 hs->secret().size())) {
54 return false;
55 }
56 assert(len == hs->secret().size());
57 return true;
58 }
59
tls13_init_key_schedule(SSL_HANDSHAKE * hs,Span<const uint8_t> psk)60 bool tls13_init_key_schedule(SSL_HANDSHAKE *hs, Span<const uint8_t> psk) {
61 if (!init_key_schedule(hs, ssl_protocol_version(hs->ssl), hs->new_cipher)) {
62 return false;
63 }
64
65 // Handback includes the whole handshake transcript, so we cannot free the
66 // transcript buffer in the handback case.
67 if (!hs->handback) {
68 hs->transcript.FreeBuffer();
69 }
70 return hkdf_extract_to_secret(hs, psk);
71 }
72
tls13_init_early_key_schedule(SSL_HANDSHAKE * hs,Span<const uint8_t> psk)73 bool tls13_init_early_key_schedule(SSL_HANDSHAKE *hs, Span<const uint8_t> psk) {
74 SSL *const ssl = hs->ssl;
75 return init_key_schedule(hs, ssl_session_protocol_version(ssl->session.get()),
76 ssl->session->cipher) &&
77 hkdf_extract_to_secret(hs, psk);
78 }
79
label_to_span(const char * label)80 static Span<const char> label_to_span(const char *label) {
81 return MakeConstSpan(label, strlen(label));
82 }
83
hkdf_expand_label(Span<uint8_t> out,const EVP_MD * digest,Span<const uint8_t> secret,Span<const char> label,Span<const uint8_t> hash)84 static bool hkdf_expand_label(Span<uint8_t> out, const EVP_MD *digest,
85 Span<const uint8_t> secret,
86 Span<const char> label,
87 Span<const uint8_t> hash) {
88 Span<const char> protocol_label = label_to_span("tls13 ");
89 ScopedCBB cbb;
90 CBB child;
91 Array<uint8_t> hkdf_label;
92 if (!CBB_init(cbb.get(), 2 + 1 + protocol_label.size() + label.size() + 1 +
93 hash.size()) ||
94 !CBB_add_u16(cbb.get(), out.size()) ||
95 !CBB_add_u8_length_prefixed(cbb.get(), &child) ||
96 !CBB_add_bytes(&child,
97 reinterpret_cast<const uint8_t *>(protocol_label.data()),
98 protocol_label.size()) ||
99 !CBB_add_bytes(&child, reinterpret_cast<const uint8_t *>(label.data()),
100 label.size()) ||
101 !CBB_add_u8_length_prefixed(cbb.get(), &child) ||
102 !CBB_add_bytes(&child, hash.data(), hash.size()) ||
103 !CBBFinishArray(cbb.get(), &hkdf_label)) {
104 return false;
105 }
106
107 return HKDF_expand(out.data(), out.size(), digest, secret.data(),
108 secret.size(), hkdf_label.data(), hkdf_label.size());
109 }
110
111 static const char kTLS13LabelDerived[] = "derived";
112
tls13_advance_key_schedule(SSL_HANDSHAKE * hs,Span<const uint8_t> in)113 bool tls13_advance_key_schedule(SSL_HANDSHAKE *hs, Span<const uint8_t> in) {
114 uint8_t derive_context[EVP_MAX_MD_SIZE];
115 unsigned derive_context_len;
116 return EVP_Digest(nullptr, 0, derive_context, &derive_context_len,
117 hs->transcript.Digest(), nullptr) &&
118 hkdf_expand_label(hs->secret(), hs->transcript.Digest(), hs->secret(),
119 label_to_span(kTLS13LabelDerived),
120 MakeConstSpan(derive_context, derive_context_len)) &&
121 hkdf_extract_to_secret(hs, in);
122 }
123
124 // derive_secret derives a secret of length |out.size()| and writes the result
125 // in |out| with the given label, the current base secret, and the most
126 // recently-saved handshake context. It returns true on success and false on
127 // error.
derive_secret(SSL_HANDSHAKE * hs,Span<uint8_t> out,Span<const char> label)128 static bool derive_secret(SSL_HANDSHAKE *hs, Span<uint8_t> out,
129 Span<const char> label) {
130 uint8_t context_hash[EVP_MAX_MD_SIZE];
131 size_t context_hash_len;
132 if (!hs->transcript.GetHash(context_hash, &context_hash_len)) {
133 return false;
134 }
135
136 return hkdf_expand_label(out, hs->transcript.Digest(), hs->secret(), label,
137 MakeConstSpan(context_hash, context_hash_len));
138 }
139
tls13_set_traffic_key(SSL * ssl,enum ssl_encryption_level_t level,enum evp_aead_direction_t direction,const SSL_SESSION * session,Span<const uint8_t> traffic_secret)140 bool tls13_set_traffic_key(SSL *ssl, enum ssl_encryption_level_t level,
141 enum evp_aead_direction_t direction,
142 const SSL_SESSION *session,
143 Span<const uint8_t> traffic_secret) {
144 uint16_t version = ssl_session_protocol_version(session);
145 UniquePtr<SSLAEADContext> traffic_aead;
146 Span<const uint8_t> secret_for_quic;
147 if (ssl->quic_method != nullptr) {
148 // Install a placeholder SSLAEADContext so that SSL accessors work. The
149 // encryption itself will be handled by the SSL_QUIC_METHOD.
150 traffic_aead =
151 SSLAEADContext::CreatePlaceholderForQUIC(version, session->cipher);
152 secret_for_quic = traffic_secret;
153 } else {
154 // Look up cipher suite properties.
155 const EVP_AEAD *aead;
156 size_t discard;
157 if (!ssl_cipher_get_evp_aead(&aead, &discard, &discard, session->cipher,
158 version, SSL_is_dtls(ssl))) {
159 return false;
160 }
161
162 const EVP_MD *digest = ssl_session_get_digest(session);
163
164 // Derive the key.
165 size_t key_len = EVP_AEAD_key_length(aead);
166 uint8_t key_buf[EVP_AEAD_MAX_KEY_LENGTH];
167 auto key = MakeSpan(key_buf, key_len);
168 if (!hkdf_expand_label(key, digest, traffic_secret, label_to_span("key"),
169 {})) {
170 return false;
171 }
172
173 // Derive the IV.
174 size_t iv_len = EVP_AEAD_nonce_length(aead);
175 uint8_t iv_buf[EVP_AEAD_MAX_NONCE_LENGTH];
176 auto iv = MakeSpan(iv_buf, iv_len);
177 if (!hkdf_expand_label(iv, digest, traffic_secret, label_to_span("iv"),
178 {})) {
179 return false;
180 }
181
182 traffic_aead = SSLAEADContext::Create(direction, session->ssl_version,
183 SSL_is_dtls(ssl), session->cipher,
184 key, Span<const uint8_t>(), iv);
185 }
186
187 if (!traffic_aead) {
188 return false;
189 }
190
191 if (traffic_secret.size() >
192 OPENSSL_ARRAY_SIZE(ssl->s3->read_traffic_secret) ||
193 traffic_secret.size() >
194 OPENSSL_ARRAY_SIZE(ssl->s3->write_traffic_secret)) {
195 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
196 return false;
197 }
198
199 if (direction == evp_aead_open) {
200 if (!ssl->method->set_read_state(ssl, level, std::move(traffic_aead),
201 secret_for_quic)) {
202 return false;
203 }
204 OPENSSL_memmove(ssl->s3->read_traffic_secret, traffic_secret.data(),
205 traffic_secret.size());
206 ssl->s3->read_traffic_secret_len = traffic_secret.size();
207 } else {
208 if (!ssl->method->set_write_state(ssl, level, std::move(traffic_aead),
209 secret_for_quic)) {
210 return false;
211 }
212 OPENSSL_memmove(ssl->s3->write_traffic_secret, traffic_secret.data(),
213 traffic_secret.size());
214 ssl->s3->write_traffic_secret_len = traffic_secret.size();
215 }
216
217 return true;
218 }
219
220
221 static const char kTLS13LabelExporter[] = "exp master";
222
223 static const char kTLS13LabelClientEarlyTraffic[] = "c e traffic";
224 static const char kTLS13LabelClientHandshakeTraffic[] = "c hs traffic";
225 static const char kTLS13LabelServerHandshakeTraffic[] = "s hs traffic";
226 static const char kTLS13LabelClientApplicationTraffic[] = "c ap traffic";
227 static const char kTLS13LabelServerApplicationTraffic[] = "s ap traffic";
228
tls13_derive_early_secret(SSL_HANDSHAKE * hs)229 bool tls13_derive_early_secret(SSL_HANDSHAKE *hs) {
230 SSL *const ssl = hs->ssl;
231 if (!derive_secret(hs, hs->early_traffic_secret(),
232 label_to_span(kTLS13LabelClientEarlyTraffic)) ||
233 !ssl_log_secret(ssl, "CLIENT_EARLY_TRAFFIC_SECRET",
234 hs->early_traffic_secret())) {
235 return false;
236 }
237 return true;
238 }
239
tls13_derive_handshake_secrets(SSL_HANDSHAKE * hs)240 bool tls13_derive_handshake_secrets(SSL_HANDSHAKE *hs) {
241 SSL *const ssl = hs->ssl;
242 if (!derive_secret(hs, hs->client_handshake_secret(),
243 label_to_span(kTLS13LabelClientHandshakeTraffic)) ||
244 !ssl_log_secret(ssl, "CLIENT_HANDSHAKE_TRAFFIC_SECRET",
245 hs->client_handshake_secret()) ||
246 !derive_secret(hs, hs->server_handshake_secret(),
247 label_to_span(kTLS13LabelServerHandshakeTraffic)) ||
248 !ssl_log_secret(ssl, "SERVER_HANDSHAKE_TRAFFIC_SECRET",
249 hs->server_handshake_secret())) {
250 return false;
251 }
252
253 return true;
254 }
255
tls13_derive_application_secrets(SSL_HANDSHAKE * hs)256 bool tls13_derive_application_secrets(SSL_HANDSHAKE *hs) {
257 SSL *const ssl = hs->ssl;
258 ssl->s3->exporter_secret_len = hs->transcript.DigestLen();
259 if (!derive_secret(hs, hs->client_traffic_secret_0(),
260 label_to_span(kTLS13LabelClientApplicationTraffic)) ||
261 !ssl_log_secret(ssl, "CLIENT_TRAFFIC_SECRET_0",
262 hs->client_traffic_secret_0()) ||
263 !derive_secret(hs, hs->server_traffic_secret_0(),
264 label_to_span(kTLS13LabelServerApplicationTraffic)) ||
265 !ssl_log_secret(ssl, "SERVER_TRAFFIC_SECRET_0",
266 hs->server_traffic_secret_0()) ||
267 !derive_secret(
268 hs, MakeSpan(ssl->s3->exporter_secret, ssl->s3->exporter_secret_len),
269 label_to_span(kTLS13LabelExporter)) ||
270 !ssl_log_secret(ssl, "EXPORTER_SECRET",
271 MakeConstSpan(ssl->s3->exporter_secret,
272 ssl->s3->exporter_secret_len))) {
273 return false;
274 }
275
276 return true;
277 }
278
279 static const char kTLS13LabelApplicationTraffic[] = "traffic upd";
280
tls13_rotate_traffic_key(SSL * ssl,enum evp_aead_direction_t direction)281 bool tls13_rotate_traffic_key(SSL *ssl, enum evp_aead_direction_t direction) {
282 Span<uint8_t> secret;
283 if (direction == evp_aead_open) {
284 secret = MakeSpan(ssl->s3->read_traffic_secret,
285 ssl->s3->read_traffic_secret_len);
286 } else {
287 secret = MakeSpan(ssl->s3->write_traffic_secret,
288 ssl->s3->write_traffic_secret_len);
289 }
290
291 const SSL_SESSION *session = SSL_get_session(ssl);
292 const EVP_MD *digest = ssl_session_get_digest(session);
293 return hkdf_expand_label(secret, digest, secret,
294 label_to_span(kTLS13LabelApplicationTraffic), {}) &&
295 tls13_set_traffic_key(ssl, ssl_encryption_application, direction,
296 session, secret);
297 }
298
299 static const char kTLS13LabelResumption[] = "res master";
300
tls13_derive_resumption_secret(SSL_HANDSHAKE * hs)301 bool tls13_derive_resumption_secret(SSL_HANDSHAKE *hs) {
302 if (hs->transcript.DigestLen() > SSL_MAX_MASTER_KEY_LENGTH) {
303 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
304 return false;
305 }
306 hs->new_session->master_key_length = hs->transcript.DigestLen();
307 return derive_secret(
308 hs,
309 MakeSpan(hs->new_session->master_key, hs->new_session->master_key_length),
310 label_to_span(kTLS13LabelResumption));
311 }
312
313 static const char kTLS13LabelFinished[] = "finished";
314
315 // tls13_verify_data sets |out| to be the HMAC of |context| using a derived
316 // Finished key for both Finished messages and the PSK binder. |out| must have
317 // space available for |EVP_MAX_MD_SIZE| bytes.
tls13_verify_data(uint8_t * out,size_t * out_len,const EVP_MD * digest,uint16_t version,Span<const uint8_t> secret,Span<const uint8_t> context)318 static bool tls13_verify_data(uint8_t *out, size_t *out_len,
319 const EVP_MD *digest, uint16_t version,
320 Span<const uint8_t> secret,
321 Span<const uint8_t> context) {
322 uint8_t key_buf[EVP_MAX_MD_SIZE];
323 auto key = MakeSpan(key_buf, EVP_MD_size(digest));
324 unsigned len;
325 if (!hkdf_expand_label(key, digest, secret,
326 label_to_span(kTLS13LabelFinished), {}) ||
327 HMAC(digest, key.data(), key.size(), context.data(), context.size(), out,
328 &len) == nullptr) {
329 return false;
330 }
331 *out_len = len;
332 return true;
333 }
334
tls13_finished_mac(SSL_HANDSHAKE * hs,uint8_t * out,size_t * out_len,bool is_server)335 bool tls13_finished_mac(SSL_HANDSHAKE *hs, uint8_t *out, size_t *out_len,
336 bool is_server) {
337 Span<const uint8_t> traffic_secret =
338 is_server ? hs->server_handshake_secret() : hs->client_handshake_secret();
339
340 uint8_t context_hash[EVP_MAX_MD_SIZE];
341 size_t context_hash_len;
342 if (!hs->transcript.GetHash(context_hash, &context_hash_len) ||
343 !tls13_verify_data(out, out_len, hs->transcript.Digest(),
344 hs->ssl->version, traffic_secret,
345 MakeConstSpan(context_hash, context_hash_len))) {
346 return 0;
347 }
348 return 1;
349 }
350
351 static const char kTLS13LabelResumptionPSK[] = "resumption";
352
tls13_derive_session_psk(SSL_SESSION * session,Span<const uint8_t> nonce)353 bool tls13_derive_session_psk(SSL_SESSION *session, Span<const uint8_t> nonce) {
354 const EVP_MD *digest = ssl_session_get_digest(session);
355 // The session initially stores the resumption_master_secret, which we
356 // override with the PSK.
357 auto session_key = MakeSpan(session->master_key, session->master_key_length);
358 return hkdf_expand_label(session_key, digest, session_key,
359 label_to_span(kTLS13LabelResumptionPSK), nonce);
360 }
361
362 static const char kTLS13LabelExportKeying[] = "exporter";
363
tls13_export_keying_material(SSL * ssl,Span<uint8_t> out,Span<const uint8_t> secret,Span<const char> label,Span<const uint8_t> context)364 bool tls13_export_keying_material(SSL *ssl, Span<uint8_t> out,
365 Span<const uint8_t> secret,
366 Span<const char> label,
367 Span<const uint8_t> context) {
368 if (secret.empty()) {
369 assert(0);
370 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
371 return false;
372 }
373
374 const EVP_MD *digest = ssl_session_get_digest(SSL_get_session(ssl));
375
376 uint8_t hash_buf[EVP_MAX_MD_SIZE];
377 uint8_t export_context_buf[EVP_MAX_MD_SIZE];
378 unsigned hash_len;
379 unsigned export_context_len;
380 if (!EVP_Digest(context.data(), context.size(), hash_buf, &hash_len, digest,
381 nullptr) ||
382 !EVP_Digest(nullptr, 0, export_context_buf, &export_context_len, digest,
383 nullptr)) {
384 return false;
385 }
386
387 auto hash = MakeConstSpan(hash_buf, hash_len);
388 auto export_context = MakeConstSpan(export_context_buf, export_context_len);
389 uint8_t derived_secret_buf[EVP_MAX_MD_SIZE];
390 auto derived_secret = MakeSpan(derived_secret_buf, EVP_MD_size(digest));
391 return hkdf_expand_label(derived_secret, digest, secret, label,
392 export_context) &&
393 hkdf_expand_label(out, digest, derived_secret,
394 label_to_span(kTLS13LabelExportKeying), hash);
395 }
396
397 static const char kTLS13LabelPSKBinder[] = "res binder";
398
tls13_psk_binder(uint8_t * out,size_t * out_len,uint16_t version,const EVP_MD * digest,Span<const uint8_t> psk,Span<const uint8_t> context)399 static bool tls13_psk_binder(uint8_t *out, size_t *out_len, uint16_t version,
400 const EVP_MD *digest, Span<const uint8_t> psk,
401 Span<const uint8_t> context) {
402 uint8_t binder_context[EVP_MAX_MD_SIZE];
403 unsigned binder_context_len;
404 if (!EVP_Digest(NULL, 0, binder_context, &binder_context_len, digest, NULL)) {
405 return false;
406 }
407
408 uint8_t early_secret[EVP_MAX_MD_SIZE] = {0};
409 size_t early_secret_len;
410 if (!HKDF_extract(early_secret, &early_secret_len, digest, psk.data(),
411 psk.size(), NULL, 0)) {
412 return false;
413 }
414
415 uint8_t binder_key_buf[EVP_MAX_MD_SIZE] = {0};
416 auto binder_key = MakeSpan(binder_key_buf, EVP_MD_size(digest));
417 if (!hkdf_expand_label(binder_key, digest,
418 MakeConstSpan(early_secret, early_secret_len),
419 label_to_span(kTLS13LabelPSKBinder),
420 MakeConstSpan(binder_context, binder_context_len)) ||
421 !tls13_verify_data(out, out_len, digest, version, binder_key, context)) {
422 return false;
423 }
424
425 assert(*out_len == EVP_MD_size(digest));
426 return true;
427 }
428
hash_transcript_and_truncated_client_hello(SSL_HANDSHAKE * hs,uint8_t * out,size_t * out_len,const EVP_MD * digest,Span<const uint8_t> client_hello,size_t binders_len)429 static bool hash_transcript_and_truncated_client_hello(
430 SSL_HANDSHAKE *hs, uint8_t *out, size_t *out_len, const EVP_MD *digest,
431 Span<const uint8_t> client_hello, size_t binders_len) {
432 // Truncate the ClientHello.
433 if (binders_len + 2 < binders_len || client_hello.size() < binders_len + 2) {
434 return false;
435 }
436 client_hello = client_hello.subspan(0, client_hello.size() - binders_len - 2);
437
438 ScopedEVP_MD_CTX ctx;
439 unsigned len;
440 if (!hs->transcript.CopyToHashContext(ctx.get(), digest) ||
441 !EVP_DigestUpdate(ctx.get(), client_hello.data(), client_hello.size()) ||
442 !EVP_DigestFinal_ex(ctx.get(), out, &len)) {
443 return false;
444 }
445
446 *out_len = len;
447 return true;
448 }
449
tls13_write_psk_binder(SSL_HANDSHAKE * hs,Span<uint8_t> msg)450 bool tls13_write_psk_binder(SSL_HANDSHAKE *hs, Span<uint8_t> msg) {
451 SSL *const ssl = hs->ssl;
452 const EVP_MD *digest = ssl_session_get_digest(ssl->session.get());
453 size_t hash_len = EVP_MD_size(digest);
454
455 ScopedEVP_MD_CTX ctx;
456 uint8_t context[EVP_MAX_MD_SIZE];
457 size_t context_len;
458 uint8_t verify_data[EVP_MAX_MD_SIZE];
459 size_t verify_data_len;
460 if (!hash_transcript_and_truncated_client_hello(
461 hs, context, &context_len, digest, msg,
462 1 /* length prefix */ + hash_len) ||
463 !tls13_psk_binder(verify_data, &verify_data_len,
464 ssl->session->ssl_version, digest,
465 MakeConstSpan(ssl->session->master_key,
466 ssl->session->master_key_length),
467 MakeConstSpan(context, context_len)) ||
468 verify_data_len != hash_len) {
469 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
470 return false;
471 }
472
473 OPENSSL_memcpy(msg.data() + msg.size() - verify_data_len, verify_data,
474 verify_data_len);
475 return true;
476 }
477
tls13_verify_psk_binder(SSL_HANDSHAKE * hs,SSL_SESSION * session,const SSLMessage & msg,CBS * binders)478 bool tls13_verify_psk_binder(SSL_HANDSHAKE *hs, SSL_SESSION *session,
479 const SSLMessage &msg, CBS *binders) {
480 uint8_t context[EVP_MAX_MD_SIZE];
481 size_t context_len;
482 uint8_t verify_data[EVP_MAX_MD_SIZE];
483 size_t verify_data_len;
484 CBS binder;
485 if (!hash_transcript_and_truncated_client_hello(hs, context, &context_len,
486 hs->transcript.Digest(),
487 msg.raw, CBS_len(binders)) ||
488 !tls13_psk_binder(
489 verify_data, &verify_data_len, hs->ssl->version,
490 hs->transcript.Digest(),
491 MakeConstSpan(session->master_key, session->master_key_length),
492 MakeConstSpan(context, context_len)) ||
493 // We only consider the first PSK, so compare against the first binder.
494 !CBS_get_u8_length_prefixed(binders, &binder)) {
495 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
496 return false;
497 }
498
499 bool binder_ok =
500 CBS_len(&binder) == verify_data_len &&
501 CRYPTO_memcmp(CBS_data(&binder), verify_data, verify_data_len) == 0;
502 #if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
503 binder_ok = true;
504 #endif
505 if (!binder_ok) {
506 OPENSSL_PUT_ERROR(SSL, SSL_R_DIGEST_CHECK_FAILED);
507 return false;
508 }
509
510 return true;
511 }
512
513 BSSL_NAMESPACE_END
514