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randombit / botan / 12548935066

30 Dec 2024 04:04PM UTC coverage: 91.262% (+0.05%) from 91.208%
12548935066

Pull #4507

github

web-flow
Merge 3aca433ed into 9b8f3cc80
Pull Request #4507: Remove support for Kyber r3 key exchange in TLS

93394 of 102336 relevant lines covered (91.26%)

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85.63
/src/lib/tls/tls_callbacks.cpp
1
/*
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* TLS Callbacks
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* (C) 2016 Jack Lloyd
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*     2017 Harry Reimann, Rohde & Schwarz Cybersecurity
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*     2022 René Meusel, Hannes Rantzsch - neXenio GmbH
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*     2023 René Meusel - Rohde & Schwarz Cybersecurity
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*
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* Botan is released under the Simplified BSD License (see license.txt)
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*/
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#include <botan/tls_callbacks.h>
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#include <botan/dh.h>
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#include <botan/dl_group.h>
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#include <botan/ecdh.h>
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#include <botan/ocsp.h>
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#include <botan/pk_algs.h>
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#include <botan/tls_algos.h>
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#include <botan/tls_exceptn.h>
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#include <botan/tls_policy.h>
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#include <botan/x509path.h>
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#include <botan/internal/ct_utils.h>
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#include <botan/internal/stl_util.h>
24

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#if defined(BOTAN_HAS_X25519)
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   #include <botan/x25519.h>
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#endif
28

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#if defined(BOTAN_HAS_X448)
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   #include <botan/x448.h>
31
#endif
32

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#if defined(BOTAN_HAS_ML_KEM)
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   #include <botan/ml_kem.h>
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#endif
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#if defined(BOTAN_HAS_FRODOKEM)
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   #include <botan/frodokem.h>
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#endif
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#if defined(BOTAN_HAS_TLS_13_PQC)
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   #include <botan/internal/hybrid_public_key.h>
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#endif
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namespace Botan {
46

47
void TLS::Callbacks::tls_inspect_handshake_msg(const Handshake_Message& /*unused*/) {
5,830✔
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   // default is no op
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}
5,830✔
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51
std::string TLS::Callbacks::tls_server_choose_app_protocol(const std::vector<std::string>& /*unused*/) {
×
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   return "";
×
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}
54

55
std::string TLS::Callbacks::tls_peer_network_identity() {
786✔
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   return "";
786✔
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}
58

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std::chrono::system_clock::time_point TLS::Callbacks::tls_current_timestamp() {
5,124✔
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   return std::chrono::system_clock::now();
5,124✔
61
}
62

63
void TLS::Callbacks::tls_modify_extensions(Extensions& /*unused*/,
2,184✔
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                                           Connection_Side /*unused*/,
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                                           Handshake_Type /*unused*/) {}
2,184✔
66

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void TLS::Callbacks::tls_examine_extensions(const Extensions& /*unused*/,
4,306✔
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                                            Connection_Side /*unused*/,
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                                            Handshake_Type /*unused*/) {}
4,306✔
70

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bool TLS::Callbacks::tls_should_persist_resumption_information(const Session& session) {
2,600✔
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   // RFC 5077 3.3
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   //    The ticket_lifetime_hint field contains a hint from the server about
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   //    how long the ticket should be stored. A value of zero is reserved to
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   //    indicate that the lifetime of the ticket is unspecified.
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   //
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   // RFC 8446 4.6.1
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   //    [A ticket_lifetime] of zero indicates that the ticket should be discarded
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   //    immediately.
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   //
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   // By default we opt to keep all sessions, except for TLS 1.3 with a lifetime
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   // hint of zero.
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   return session.lifetime_hint().count() > 0 || session.version().is_pre_tls_13();
2,600✔
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}
85

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void TLS::Callbacks::tls_verify_cert_chain(const std::vector<X509_Certificate>& cert_chain,
110✔
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                                           const std::vector<std::optional<OCSP::Response>>& ocsp_responses,
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                                           const std::vector<Certificate_Store*>& trusted_roots,
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                                           Usage_Type usage,
90
                                           std::string_view hostname,
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                                           const TLS::Policy& policy) {
92
   if(cert_chain.empty()) {
110✔
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      throw Invalid_Argument("Certificate chain was empty");
×
94
   }
95

96
   Path_Validation_Restrictions restrictions(policy.require_cert_revocation_info(),
110✔
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                                             policy.minimum_signature_strength());
330✔
98

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   Path_Validation_Result result = x509_path_validate(cert_chain,
110✔
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                                                      restrictions,
101
                                                      trusted_roots,
102
                                                      hostname,
103
                                                      usage,
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                                                      tls_current_timestamp(),
110✔
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                                                      tls_verify_cert_chain_ocsp_timeout(),
110✔
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                                                      ocsp_responses);
110✔
107

108
   if(!result.successful_validation()) {
110✔
109
      throw TLS_Exception(Alert::BadCertificate, "Certificate validation failure: " + result.result_string());
×
110
   }
111
}
110✔
112

113
void TLS::Callbacks::tls_verify_raw_public_key(const Public_Key& raw_public_key,
×
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                                               Usage_Type usage,
115
                                               std::string_view hostname,
116
                                               const TLS::Policy& policy) {
117
   BOTAN_UNUSED(raw_public_key, usage, hostname, policy);
×
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   // There is no good default implementation for authenticating raw public key.
119
   // Applications that wish to use them for authentication, must override this.
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   throw TLS_Exception(Alert::CertificateUnknown, "Application did not provide a means to validate the raw public key");
×
121
}
122

123
std::optional<OCSP::Response> TLS::Callbacks::tls_parse_ocsp_response(const std::vector<uint8_t>& raw_response) {
×
124
   try {
×
125
      return OCSP::Response(raw_response);
×
126
   } catch(const Decoding_Error&) {
×
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      // ignore parsing errors and just ignore the broken OCSP response
128
      return std::nullopt;
×
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   }
×
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}
131

132
std::vector<std::vector<uint8_t>> TLS::Callbacks::tls_provide_cert_chain_status(
254✔
133
   const std::vector<X509_Certificate>& chain, const Certificate_Status_Request& csr) {
134
   std::vector<std::vector<uint8_t>> result(chain.size());
254✔
135
   if(!chain.empty()) {
254✔
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      result[0] = tls_provide_cert_status(chain, csr);
254✔
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   }
138
   return result;
246✔
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}
8✔
140

141
std::vector<uint8_t> TLS::Callbacks::tls_sign_message(const Private_Key& key,
986✔
142
                                                      RandomNumberGenerator& rng,
143
                                                      std::string_view padding,
144
                                                      Signature_Format format,
145
                                                      const std::vector<uint8_t>& msg) {
146
   PK_Signer signer(key, rng, padding, format);
986✔
147

148
   return signer.sign_message(msg, rng);
1,971✔
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}
986✔
150

151
bool TLS::Callbacks::tls_verify_message(const Public_Key& key,
1,229✔
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                                        std::string_view padding,
153
                                        Signature_Format format,
154
                                        const std::vector<uint8_t>& msg,
155
                                        const std::vector<uint8_t>& sig) {
156
   PK_Verifier verifier(key, padding, format);
1,229✔
157

158
   return verifier.verify_message(msg, sig);
2,458✔
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}
1,229✔
160

161
namespace {
162

163
bool is_dh_group(const std::variant<TLS::Group_Params, DL_Group>& group) {
4,848✔
164
   return std::holds_alternative<DL_Group>(group) || std::get<TLS::Group_Params>(group).is_dh_named_group();
9,672✔
165
}
166

167
DL_Group get_dl_group(const std::variant<TLS::Group_Params, DL_Group>& group) {
28✔
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   BOTAN_ASSERT_NOMSG(is_dh_group(group));
28✔
169

170
   // TLS 1.2 allows specifying arbitrary DL_Group parameters in-lieu of
171
   // a standardized DH group identifier. TLS 1.3 just offers pre-defined
172
   // groups.
173
   return std::visit(
28✔
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      overloaded{[](const DL_Group& dl_group) { return dl_group; },
12✔
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                 [&](TLS::Group_Params group_param) { return DL_Group(group_param.to_string().value()); }},
48✔
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      group);
28✔
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}
178

179
}  // namespace
180

181
std::unique_ptr<Public_Key> TLS::Callbacks::tls_deserialize_peer_public_key(
2,104✔
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   const std::variant<TLS::Group_Params, DL_Group>& group, std::span<const uint8_t> key_bits) {
183
   if(is_dh_group(group)) {
2,104✔
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      // TLS 1.2 allows specifying arbitrary DL_Group parameters in-lieu of
185
      // a standardized DH group identifier.
186
      const auto dl_group = get_dl_group(group);
12✔
187

188
      auto Y = BigInt::from_bytes(key_bits);
12✔
189

190
      /*
191
       * A basic check for key validity. As we do not know q here we
192
       * cannot check that Y is in the right subgroup. However since
193
       * our key is ephemeral there does not seem to be any
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       * advantage to bogus keys anyway.
195
       */
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      if(Y <= 1 || Y >= dl_group.get_p() - 1) {
24✔
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         throw Decoding_Error("Server sent bad DH key for DHE exchange");
×
198
      }
199

200
      return std::make_unique<DH_PublicKey>(dl_group, Y);
24✔
201
   }
24✔
202

203
   // The special case for TLS 1.2 with an explicit DH group definition is
204
   // handled above. All other cases are based on the opaque group definition.
205
   BOTAN_ASSERT_NOMSG(std::holds_alternative<TLS::Group_Params>(group));
2,092✔
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   const auto group_params = std::get<TLS::Group_Params>(group);
2,092✔
207

208
   if(group_params.is_ecdh_named_curve()) {
2,092✔
209
      const auto ec_group = EC_Group::from_name(group_params.to_string().value());
192✔
210
      return std::make_unique<ECDH_PublicKey>(ec_group, ec_group.OS2ECP(key_bits));
156✔
211
   }
96✔
212

213
#if defined(BOTAN_HAS_X25519)
214
   if(group_params.is_x25519()) {
1,996✔
215
      return std::make_unique<X25519_PublicKey>(key_bits);
3,934✔
216
   }
217
#endif
218

219
#if defined(BOTAN_HAS_X448)
220
   if(group_params.is_x448()) {
25✔
221
      return std::make_unique<X448_PublicKey>(key_bits);
8✔
222
   }
223
#endif
224

225
#if defined(BOTAN_HAS_TLS_13_PQC)
226
   if(group_params.is_pqc_hybrid()) {
21✔
227
      return Hybrid_KEM_PublicKey::load_for_group(group_params, key_bits);
37✔
228
   }
229
#endif
230

231
#if defined(BOTAN_HAS_ML_KEM)
232
   if(group_params.is_pure_ml_kem()) {
1✔
233
      return std::make_unique<ML_KEM_PublicKey>(key_bits, ML_KEM_Mode(group_params.to_string().value()));
4✔
234
   }
235
#endif
236

237
#if defined(BOTAN_HAS_FRODOKEM)
238
   if(group_params.is_pure_frodokem()) {
×
239
      return std::make_unique<FrodoKEM_PublicKey>(key_bits, FrodoKEMMode(group_params.to_string().value()));
×
240
   }
241
#endif
242

243
   throw Decoding_Error("cannot create a key offering without a group definition");
×
244
}
245

246
std::unique_ptr<Private_Key> TLS::Callbacks::tls_kem_generate_key(TLS::Group_Params group, RandomNumberGenerator& rng) {
1,060✔
247
#if defined(BOTAN_HAS_ML_KEM)
248
   if(group.is_pure_ml_kem()) {
1,060✔
249
      return std::make_unique<ML_KEM_PrivateKey>(rng, ML_KEM_Mode(group.to_string().value()));
3✔
250
   }
251
#endif
252

253
#if defined(BOTAN_HAS_FRODOKEM)
254
   if(group.is_pure_frodokem()) {
1,059✔
255
      return std::make_unique<FrodoKEM_PrivateKey>(rng, FrodoKEMMode(group.to_string().value()));
×
256
   }
257
#endif
258

259
#if defined(BOTAN_HAS_TLS_13_PQC)
260
   if(group.is_pqc_hybrid()) {
1,059✔
261
      return Hybrid_KEM_PrivateKey::generate_from_group(group, rng);
21✔
262
   }
263
#endif
264

265
   return tls_generate_ephemeral_key(group, rng);
3,114✔
266
}
267

268
KEM_Encapsulation TLS::Callbacks::tls_kem_encapsulate(TLS::Group_Params group,
383✔
269
                                                      const std::vector<uint8_t>& encoded_public_key,
270
                                                      RandomNumberGenerator& rng,
271
                                                      const Policy& policy) {
272
   if(group.is_kem()) {
383✔
273
      auto kem_pub_key = [&] {
60✔
274
         try {
21✔
275
            return tls_deserialize_peer_public_key(group, encoded_public_key);
42✔
276
         } catch(const Decoding_Error& ex) {
3✔
277
            // This exception means that the public key was invalid. However,
278
            // TLS' DecodeError would imply that a protocol message was invalid.
279
            throw TLS_Exception(Alert::IllegalParameter, ex.what());
3✔
280
         }
3✔
281
      }();
21✔
282

283
      BOTAN_ASSERT_NONNULL(kem_pub_key);
18✔
284
      policy.check_peer_key_acceptable(*kem_pub_key);
18✔
285

286
      try {
18✔
287
         return PK_KEM_Encryptor(*kem_pub_key, "Raw").encrypt(rng);
18✔
288
      } catch(const Invalid_Argument& ex) {
1✔
289
         throw TLS_Exception(Alert::IllegalParameter, ex.what());
1✔
290
      }
1✔
291
   } else {
18✔
292
      // TODO: We could use the KEX_to_KEM_Adapter to remove the case distinction
293
      //       of KEM and KEX. However, the workarounds in this adapter class
294
      //       should first be addressed.
295
      auto ephemeral_keypair = tls_generate_ephemeral_key(group, rng);
362✔
296
      BOTAN_ASSERT_NONNULL(ephemeral_keypair);
362✔
297
      return {ephemeral_keypair->public_value(),
724✔
298
              tls_ephemeral_key_agreement(group, *ephemeral_keypair, encoded_public_key, rng, policy)};
724✔
299
   }
350✔
300
}
301

302
secure_vector<uint8_t> TLS::Callbacks::tls_kem_decapsulate(TLS::Group_Params group,
442✔
303
                                                           const Private_Key& private_key,
304
                                                           const std::vector<uint8_t>& encapsulated_bytes,
305
                                                           RandomNumberGenerator& rng,
306
                                                           const Policy& policy) {
307
   if(group.is_kem()) {
442✔
308
      PK_KEM_Decryptor kemdec(private_key, rng, "Raw");
22✔
309
      if(encapsulated_bytes.size() != kemdec.encapsulated_key_length()) {
22✔
310
         throw TLS_Exception(Alert::IllegalParameter, "Invalid encapsulated key length");
2✔
311
      }
312
      return kemdec.decrypt(encapsulated_bytes, 0, {});
20✔
313
   }
22✔
314

315
   try {
420✔
316
      auto& key_agreement_key = dynamic_cast<const PK_Key_Agreement_Key&>(private_key);
420✔
317
      return tls_ephemeral_key_agreement(group, key_agreement_key, encapsulated_bytes, rng, policy);
840✔
318
   } catch(const std::bad_cast&) {
12✔
319
      throw Invalid_Argument("provided ephemeral key is not a PK_Key_Agreement_Key");
×
320
   }
×
321
}
322

323
std::unique_ptr<PK_Key_Agreement_Key> TLS::Callbacks::tls_generate_ephemeral_key(
2,716✔
324
   const std::variant<TLS::Group_Params, DL_Group>& group, RandomNumberGenerator& rng) {
325
   if(is_dh_group(group)) {
2,716✔
326
      const DL_Group dl_group = get_dl_group(group);
16✔
327
      return std::make_unique<DH_PrivateKey>(rng, dl_group);
32✔
328
   }
16✔
329

330
   BOTAN_ASSERT_NOMSG(std::holds_alternative<TLS::Group_Params>(group));
2,700✔
331
   const auto group_params = std::get<TLS::Group_Params>(group);
2,700✔
332

333
   if(group_params.is_ecdh_named_curve()) {
2,700✔
334
      const auto ec_group = EC_Group::from_name(group_params.to_string().value());
290✔
335
      return std::make_unique<ECDH_PrivateKey>(rng, ec_group);
290✔
336
   }
145✔
337

338
#if defined(BOTAN_HAS_X25519)
339
   if(group_params.is_x25519()) {
2,555✔
340
      return std::make_unique<X25519_PrivateKey>(rng);
5,102✔
341
   }
342
#endif
343

344
#if defined(BOTAN_HAS_X448)
345
   if(group_params.is_x448()) {
4✔
346
      return std::make_unique<X448_PrivateKey>(rng);
8✔
347
   }
348
#endif
349

350
   if(group_params.is_kem()) {
×
351
      throw TLS_Exception(Alert::IllegalParameter, "cannot generate an ephemeral KEX key for a KEM");
×
352
   }
353

354
   throw TLS_Exception(Alert::DecodeError, "cannot create a key offering without a group definition");
×
355
}
356

357
secure_vector<uint8_t> TLS::Callbacks::tls_ephemeral_key_agreement(
2,083✔
358
   const std::variant<TLS::Group_Params, DL_Group>& group,
359
   const PK_Key_Agreement_Key& private_key,
360
   const std::vector<uint8_t>& public_value,
361
   RandomNumberGenerator& rng,
362
   const Policy& policy) {
363
   const auto kex_pub_key = [&]() {
6,205✔
364
      try {
2,083✔
365
         return tls_deserialize_peer_public_key(group, public_value);
2,083✔
366
      } catch(const Decoding_Error& ex) {
44✔
367
         // This exception means that the public key was invalid. However,
368
         // TLS' DecodeError would imply that a protocol message was invalid.
369
         throw TLS_Exception(Alert::IllegalParameter, ex.what());
44✔
370
      }
44✔
371
   }();
2,083✔
372

373
   BOTAN_ASSERT_NONNULL(kex_pub_key);
2,039✔
374
   policy.check_peer_key_acceptable(*kex_pub_key);
2,039✔
375

376
   // RFC 8422 - 5.11.
377
   //   With X25519 and X448, a receiving party MUST check whether the
378
   //   computed premaster secret is the all-zero value and abort the
379
   //   handshake if so, as described in Section 6 of [RFC7748].
380
   //
381
   // This is done within the key agreement operation and throws
382
   // an Invalid_Argument exception if the shared secret is all-zero.
383
   try {
2,039✔
384
      PK_Key_Agreement ka(private_key, rng, "Raw");
2,039✔
385
      return ka.derive_key(0, kex_pub_key->raw_public_key_bits()).bits_of();
6,113✔
386
   } catch(const Invalid_Argument& ex) {
2,043✔
387
      throw TLS_Exception(Alert::IllegalParameter, ex.what());
4✔
388
   }
4✔
389
}
2,035✔
390

391
}  // namespace Botan
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