6421338519

Committed 05 Oct 2023 03:44PM UTC coverage: 91.703% (-0.08%) from 91.783%

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Commit Message

Merge pull request #3609 from Rohde-Schwarz/tls13/kem_establishment

[TLS 1.3] Hybrid PQ/T key establishment

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86.27

/src/lib/tls/tls12/msg_client_kex.cpp

/*
* Client Key Exchange Message
* (C) 2004-2010,2016 Jack Lloyd
*     2017 Harry Reimann, Rohde & Schwarz Cybersecurity
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/tls_messages.h>

#include <botan/rng.h>
#include <botan/tls_extensions.h>

#include <botan/credentials_manager.h>
#include <botan/internal/ct_utils.h>
#include <botan/internal/stl_util.h>
#include <botan/internal/tls_handshake_hash.h>
#include <botan/internal/tls_handshake_io.h>
#include <botan/internal/tls_handshake_state.h>
#include <botan/internal/tls_reader.h>

#include <botan/ecdh.h>
#include <botan/rsa.h>

namespace Botan::TLS {

/*
* Create a new Client Key Exchange message
*/
Client_Key_Exchange::Client_Key_Exchange(Handshake_IO& io,
                                         Handshake_State& state,
                                         const Policy& policy,
                                         Credentials_Manager& creds,
                                         const Public_Key* server_public_key,
                                         std::string_view hostname,
                                         RandomNumberGenerator& rng) {
   const Kex_Algo kex_algo = state.ciphersuite().kex_method();

   if(kex_algo == Kex_Algo::PSK) {
      std::string identity_hint;

      if(state.server_kex()) {
         TLS_Data_Reader reader("ClientKeyExchange", state.server_kex()->params());
         identity_hint = reader.get_string(2, 0, 65535);
      }

      m_psk_identity = creds.psk_identity("tls-client", std::string(hostname), identity_hint);

      append_tls_length_value(m_key_material, to_byte_vector(m_psk_identity.value()), 2);

      SymmetricKey psk = creds.psk("tls-client", std::string(hostname), m_psk_identity.value());

      std::vector<uint8_t> zeros(psk.length());

      append_tls_length_value(m_pre_master, zeros, 2);
      append_tls_length_value(m_pre_master, psk.bits_of(), 2);
   } else if(state.server_kex()) {
      TLS_Data_Reader reader("ClientKeyExchange", state.server_kex()->params());

      SymmetricKey psk;

      if(kex_algo == Kex_Algo::ECDHE_PSK) {
         std::string identity_hint = reader.get_string(2, 0, 65535);

         m_psk_identity = creds.psk_identity("tls-client", std::string(hostname), identity_hint);

         append_tls_length_value(m_key_material, to_byte_vector(m_psk_identity.value()), 2);

         psk = creds.psk("tls-client", std::string(hostname), m_psk_identity.value());
      }

      if(kex_algo == Kex_Algo::DH) {
         const auto modulus = BigInt::decode(reader.get_range<uint8_t>(2, 1, 65535));
         const auto generator = BigInt::decode(reader.get_range<uint8_t>(2, 1, 65535));
         const std::vector<uint8_t> peer_public_value = reader.get_range<uint8_t>(2, 1, 65535);

         if(reader.remaining_bytes()) {
            throw Decoding_Error("Bad params size for DH key exchange");
         }

         DL_Group group(modulus, generator);

         if(!group.verify_group(rng, false)) {
            throw TLS_Exception(Alert::InsufficientSecurity, "DH group validation failed");
         }

         const auto private_key = state.callbacks().tls_generate_ephemeral_key(group, rng);
         auto shared_secret = CT::strip_leading_zeros(
            state.callbacks().tls_ephemeral_key_agreement(group, *private_key, peer_public_value, rng, policy));

         if(kex_algo == Kex_Algo::DH) {
            m_pre_master = std::move(shared_secret);
         } else {
            append_tls_length_value(m_pre_master, shared_secret, 2);
            append_tls_length_value(m_pre_master, psk.bits_of(), 2);
         }

         append_tls_length_value(m_key_material, private_key->public_value(), 2);
      } else if(kex_algo == Kex_Algo::ECDH || kex_algo == Kex_Algo::ECDHE_PSK) {
         const uint8_t curve_type = reader.get_byte();
         if(curve_type != 3) {
            throw Decoding_Error("Server sent non-named ECC curve");
         }

         const Group_Params curve_id = static_cast<Group_Params>(reader.get_uint16_t());
         const std::vector<uint8_t> peer_public_value = reader.get_range<uint8_t>(1, 1, 255);

         if(!is_ecdh(curve_id) && !is_x25519(curve_id)) {
            throw TLS_Exception(Alert::HandshakeFailure,
                                "Server selected a group that is not compatible with the negotiated ciphersuite");
         }

         if(policy.choose_key_exchange_group({curve_id}, {}) != curve_id) {
            throw TLS_Exception(Alert::HandshakeFailure, "Server sent ECC curve prohibited by policy");
         }

         const auto private_key = state.callbacks().tls_generate_ephemeral_key(curve_id, rng);
         auto shared_secret =
            state.callbacks().tls_ephemeral_key_agreement(curve_id, *private_key, peer_public_value, rng, policy);

         // RFC 8422 - 5.11.
         //   With X25519 and X448, a receiving party MUST check whether the
         //   computed premaster secret is the all-zero value and abort the
         //   handshake if so, as described in Section 6 of [RFC7748].
         if(curve_id == Group_Params::X25519 && CT::all_zeros(shared_secret.data(), shared_secret.size()).is_set()) {
            throw TLS_Exception(Alert::DecryptError, "Bad X25519 key exchange");
         }

         if(kex_algo == Kex_Algo::ECDH) {
            m_pre_master = std::move(shared_secret);
         } else {
            append_tls_length_value(m_pre_master, shared_secret, 2);
            append_tls_length_value(m_pre_master, psk.bits_of(), 2);
         }

         if(is_ecdh(curve_id)) {
            auto ecdh_key = dynamic_cast<ECDH_PublicKey*>(private_key.get());
            if(!ecdh_key) {
               throw TLS_Exception(Alert::InternalError, "Application did not provide a ECDH_PublicKey");
            }
            append_tls_length_value(m_key_material,
                                    ecdh_key->public_value(state.server_hello()->prefers_compressed_ec_points()
                                                              ? EC_Point_Format::Compressed
                                                              : EC_Point_Format::Uncompressed),
                                    1);
         } else {
            append_tls_length_value(m_key_material, private_key->public_value(), 1);
         }
      } else {
         throw Internal_Error("Client_Key_Exchange: Unknown key exchange method was negotiated");
      }

      reader.assert_done();
   } else {
      // No server key exchange msg better mean RSA kex + RSA key in cert

      if(kex_algo != Kex_Algo::STATIC_RSA) {
         throw Unexpected_Message("No server kex message, but negotiated a key exchange that required it");
      }

      if(!server_public_key) {
         throw Internal_Error("No server public key for RSA exchange");
      }

      if(auto rsa_pub = dynamic_cast<const RSA_PublicKey*>(server_public_key)) {
         const Protocol_Version offered_version = state.client_hello()->legacy_version();

         rng.random_vec(m_pre_master, 48);
         m_pre_master[0] = offered_version.major_version();
         m_pre_master[1] = offered_version.minor_version();

         PK_Encryptor_EME encryptor(*rsa_pub, rng, "PKCS1v15");

         const std::vector<uint8_t> encrypted_key = encryptor.encrypt(m_pre_master, rng);

         append_tls_length_value(m_key_material, encrypted_key, 2);
      } else {
         throw TLS_Exception(Alert::HandshakeFailure,
                             "Expected a RSA key in server cert but got " + server_public_key->algo_name());
      }
   }

   state.hash().update(io.send(*this));
}

/*
* Read a Client Key Exchange message
*/
Client_Key_Exchange::Client_Key_Exchange(const std::vector<uint8_t>& contents,
                                         const Handshake_State& state,
                                         const Private_Key* server_rsa_kex_key,
                                         Credentials_Manager& creds,
                                         const Policy& policy,
                                         RandomNumberGenerator& rng) {
   const Kex_Algo kex_algo = state.ciphersuite().kex_method();

   if(kex_algo == Kex_Algo::STATIC_RSA) {
      BOTAN_ASSERT(state.server_certs() && !state.server_certs()->cert_chain().empty(),
                   "RSA key exchange negotiated so server sent a certificate");

      if(!server_rsa_kex_key) {
         throw Internal_Error("Expected RSA kex but no server kex key set");
      }

      if(server_rsa_kex_key->algo_name() != "RSA") {
         throw Internal_Error("Expected RSA key but got " + server_rsa_kex_key->algo_name());
      }

      TLS_Data_Reader reader("ClientKeyExchange", contents);
      const std::vector<uint8_t> encrypted_pre_master = reader.get_range<uint8_t>(2, 0, 65535);
      reader.assert_done();

      PK_Decryptor_EME decryptor(*server_rsa_kex_key, rng, "PKCS1v15");

      const uint8_t client_major = state.client_hello()->legacy_version().major_version();
      const uint8_t client_minor = state.client_hello()->legacy_version().minor_version();

      /*
      * PK_Decryptor::decrypt_or_random will return a random value if
      * either the length does not match the expected value or if the
      * version number embedded in the PMS does not match the one sent
      * in the client hello.
      */
      const size_t expected_plaintext_size = 48;
      const size_t expected_content_size = 2;
      const uint8_t expected_content_bytes[expected_content_size] = {client_major, client_minor};
      const uint8_t expected_content_pos[expected_content_size] = {0, 1};

      m_pre_master = decryptor.decrypt_or_random(encrypted_pre_master.data(),
                                                 encrypted_pre_master.size(),
                                                 expected_plaintext_size,
                                                 rng,
                                                 expected_content_bytes,
                                                 expected_content_pos,
                                                 expected_content_size);
   } else {
      TLS_Data_Reader reader("ClientKeyExchange", contents);

      SymmetricKey psk;

      if(key_exchange_is_psk(kex_algo)) {
         m_psk_identity = reader.get_string(2, 0, 65535);

         psk = creds.psk("tls-server", state.client_hello()->sni_hostname(), m_psk_identity.value());

         if(psk.length() == 0) {
            if(policy.hide_unknown_users()) {
               psk = SymmetricKey(rng, 16);
            } else {
               throw TLS_Exception(Alert::UnknownPSKIdentity, "No PSK for identifier " + m_psk_identity.value());
            }
         }
      }

      if(kex_algo == Kex_Algo::PSK) {
         std::vector<uint8_t> zeros(psk.length());
         append_tls_length_value(m_pre_master, zeros, 2);
         append_tls_length_value(m_pre_master, psk.bits_of(), 2);
      } else if(kex_algo == Kex_Algo::DH || kex_algo == Kex_Algo::ECDH || kex_algo == Kex_Algo::ECDHE_PSK) {
         const PK_Key_Agreement_Key& ka_key = state.server_kex()->server_kex_key();

         const std::vector<uint8_t> client_pubkey = (ka_key.algo_name() == "DH")
                                                       ? reader.get_range<uint8_t>(2, 0, 65535)
                                                       : reader.get_range<uint8_t>(1, 1, 255);

         const auto shared_group = state.server_kex()->shared_group();
         BOTAN_STATE_CHECK(shared_group && shared_group.value() != Group_Params::NONE);

         try {
            auto shared_secret =
               state.callbacks().tls_ephemeral_key_agreement(shared_group.value(), ka_key, client_pubkey, rng, policy);

            if(ka_key.algo_name() == "DH") {
               shared_secret = CT::strip_leading_zeros(shared_secret);
            }

            if(kex_algo == Kex_Algo::ECDH || kex_algo == Kex_Algo::ECDHE_PSK) {
               // RFC 8422 - 5.11.
               //   With X25519 and X448, a receiving party MUST check whether the
               //   computed premaster secret is the all-zero value and abort the
               //   handshake if so, as described in Section 6 of [RFC7748].
               BOTAN_ASSERT_NOMSG(state.server_kex()->params().size() >= 3);
               Group_Params group = static_cast<Group_Params>(state.server_kex()->params().at(2));
               if(group == Group_Params::X25519 && CT::all_zeros(shared_secret.data(), shared_secret.size()).is_set()) {
                  throw TLS_Exception(Alert::DecryptError, "Bad X25519 key exchange");
               }
            }

            if(kex_algo == Kex_Algo::ECDHE_PSK) {
               append_tls_length_value(m_pre_master, shared_secret, 2);
               append_tls_length_value(m_pre_master, psk.bits_of(), 2);
            } else {
               m_pre_master = shared_secret;
            }
         } catch(Invalid_Argument& e) {
            throw TLS_Exception(Alert::IllegalParameter, e.what());
         } catch(TLS_Exception& e) {
            // NOLINTNEXTLINE(cert-err60-cpp)
            throw e;
         } catch(std::exception&) {
            /*
            * Something failed in the DH/ECDH computation. To avoid possible
            * attacks which are based on triggering and detecting some edge
            * failure condition, randomize the pre-master output and carry on,
            * allowing the protocol to fail later in the finished checks.
            */
            rng.random_vec(m_pre_master, ka_key.public_value().size());
         }

         reader.assert_done();
      } else {
         throw Internal_Error("Client_Key_Exchange: Unknown key exchange negotiated");
      }
   }
}

}  // namespace Botan::TLS

1	/*
2	* Client Key Exchange Message
3	* (C) 2004-2010,2016 Jack Lloyd
4	* 2017 Harry Reimann, Rohde & Schwarz Cybersecurity
5	*
6	* Botan is released under the Simplified BSD License (see license.txt)
7	*/
8
9	#include <botan/tls_messages.h>
10
11	#include <botan/rng.h>
12	#include <botan/tls_extensions.h>
13
14	#include <botan/credentials_manager.h>
15	#include <botan/internal/ct_utils.h>
16	#include <botan/internal/stl_util.h>
17	#include <botan/internal/tls_handshake_hash.h>
18	#include <botan/internal/tls_handshake_io.h>
19	#include <botan/internal/tls_handshake_state.h>
20	#include <botan/internal/tls_reader.h>
21
22	#include <botan/ecdh.h>
23	#include <botan/rsa.h>
24
25	namespace Botan::TLS {
26
27	/*
28	* Create a new Client Key Exchange message
29	*/
30	Client_Key_Exchange::Client_Key_Exchange(Handshake_IO& io,	765✔
31	Handshake_State& state,
32	const Policy& policy,
33	Credentials_Manager& creds,
34	const Public_Key* server_public_key,
35	std::string_view hostname,
36	RandomNumberGenerator& rng) {	765✔
37	const Kex_Algo kex_algo = state.ciphersuite().kex_method();	765✔
38
39	if(kex_algo == Kex_Algo::PSK) {	765✔
40	std::string identity_hint;	42✔
41
42	if(state.server_kex()) {	42✔
43	TLS_Data_Reader reader("ClientKeyExchange", state.server_kex()->params());	26✔
44	identity_hint = reader.get_string(2, 0, 65535);	26✔
45	}
46
47	m_psk_identity = creds.psk_identity("tls-client", std::string(hostname), identity_hint);	84✔
48
49	append_tls_length_value(m_key_material, to_byte_vector(m_psk_identity.value()), 2);	84✔
50
51	SymmetricKey psk = creds.psk("tls-client", std::string(hostname), m_psk_identity.value());	126✔
52
53	std::vector<uint8_t> zeros(psk.length());	42✔
54
55	append_tls_length_value(m_pre_master, zeros, 2);	42✔
56	append_tls_length_value(m_pre_master, psk.bits_of(), 2);	126✔
57	} else if(state.server_kex()) {	807✔
58	TLS_Data_Reader reader("ClientKeyExchange", state.server_kex()->params());	669✔
59
60	SymmetricKey psk;	669✔
61
62	if(kex_algo == Kex_Algo::ECDHE_PSK) {	669✔
63	std::string identity_hint = reader.get_string(2, 0, 65535);	24✔
64
65	m_psk_identity = creds.psk_identity("tls-client", std::string(hostname), identity_hint);	48✔
66
67	append_tls_length_value(m_key_material, to_byte_vector(m_psk_identity.value()), 2);	48✔
68
69	psk = creds.psk("tls-client", std::string(hostname), m_psk_identity.value());	76✔
70	}	24✔
71
72	if(kex_algo == Kex_Algo::DH) {	669✔
73	const auto modulus = BigInt::decode(reader.get_range<uint8_t>(2, 1, 65535));	16✔
74	const auto generator = BigInt::decode(reader.get_range<uint8_t>(2, 1, 65535));	8✔
75	const std::vector<uint8_t> peer_public_value = reader.get_range<uint8_t>(2, 1, 65535);	4✔
76
77	if(reader.remaining_bytes()) {	4✔
78	throw Decoding_Error("Bad params size for DH key exchange");	×
79	}
80
81	DL_Group group(modulus, generator);	4✔
82
83	if(!group.verify_group(rng, false)) {	4✔
84	throw TLS_Exception(Alert::InsufficientSecurity, "DH group validation failed");	×
85	}
86
87	const auto private_key = state.callbacks().tls_generate_ephemeral_key(group, rng);	4✔
88	auto shared_secret = CT::strip_leading_zeros(	4✔
89	state.callbacks().tls_ephemeral_key_agreement(group, *private_key, peer_public_value, rng, policy));	12✔
90
91	if(kex_algo == Kex_Algo::DH) {	4✔
92	m_pre_master = std::move(shared_secret);	4✔
93	} else {
94	append_tls_length_value(m_pre_master, shared_secret, 2);
95	append_tls_length_value(m_pre_master, psk.bits_of(), 2);
96	}
97
98	append_tls_length_value(m_key_material, private_key->public_value(), 2);	12✔
99	} else if(kex_algo == Kex_Algo::ECDH \|\| kex_algo == Kex_Algo::ECDHE_PSK) {	689✔
100	const uint8_t curve_type = reader.get_byte();	665✔
101	if(curve_type != 3) {	665✔
102	throw Decoding_Error("Server sent non-named ECC curve");	×
103	}
104
105	const Group_Params curve_id = static_cast<Group_Params>(reader.get_uint16_t());	665✔
106	const std::vector<uint8_t> peer_public_value = reader.get_range<uint8_t>(1, 1, 255);	665✔
107
108	if(!is_ecdh(curve_id) && !is_x25519(curve_id)) {	665✔
109	throw TLS_Exception(Alert::HandshakeFailure,	6✔
110	"Server selected a group that is not compatible with the negotiated ciphersuite");	12✔
111	}
112
113	if(policy.choose_key_exchange_group({curve_id}, {}) != curve_id) {	1,318✔
114	throw TLS_Exception(Alert::HandshakeFailure, "Server sent ECC curve prohibited by policy");	1✔
115	}
116
117	const auto private_key = state.callbacks().tls_generate_ephemeral_key(curve_id, rng);	666✔
118	auto shared_secret =	658✔
119	state.callbacks().tls_ephemeral_key_agreement(curve_id, *private_key, peer_public_value, rng, policy);	659✔
120
121	// RFC 8422 - 5.11.
122	// With X25519 and X448, a receiving party MUST check whether the
123	// computed premaster secret is the all-zero value and abort the
124	// handshake if so, as described in Section 6 of [RFC7748].
125	if(curve_id == Group_Params::X25519 && CT::all_zeros(shared_secret.data(), shared_secret.size()).is_set()) {	1,301✔
126	throw TLS_Exception(Alert::DecryptError, "Bad X25519 key exchange");	×
127	}
128
129	if(kex_algo == Kex_Algo::ECDH) {	657✔
130	m_pre_master = std::move(shared_secret);	633✔
131	} else {
132	append_tls_length_value(m_pre_master, shared_secret, 2);	24✔
133	append_tls_length_value(m_pre_master, psk.bits_of(), 2);	72✔
134	}
135
136	if(is_ecdh(curve_id)) {	657✔
137	auto ecdh_key = dynamic_cast<ECDH_PublicKey*>(private_key.get());	13✔
138	if(!ecdh_key) {	13✔
139	throw TLS_Exception(Alert::InternalError, "Application did not provide a ECDH_PublicKey");	×
140	}
141	append_tls_length_value(m_key_material,	13✔
142	ecdh_key->public_value(state.server_hello()->prefers_compressed_ec_points()	39✔
143	? EC_Point_Format::Compressed
144	: EC_Point_Format::Uncompressed),
145	1);
146	} else {
147	append_tls_length_value(m_key_material, private_key->public_value(), 1);	1,932✔
148	}
149	} else {	1,980✔
150	throw Internal_Error("Client_Key_Exchange: Unknown key exchange method was negotiated");	×
151	}
152
153	reader.assert_done();	661✔
154	} else {	669✔
155	// No server key exchange msg better mean RSA kex + RSA key in cert
156
157	if(kex_algo != Kex_Algo::STATIC_RSA) {	54✔
158	throw Unexpected_Message("No server kex message, but negotiated a key exchange that required it");	×
159	}
160
161	if(!server_public_key) {	54✔
162	throw Internal_Error("No server public key for RSA exchange");	×
163	}
164
165	if(auto rsa_pub = dynamic_cast<const RSA_PublicKey*>(server_public_key)) {	54✔
166	const Protocol_Version offered_version = state.client_hello()->legacy_version();	54✔
167
168	rng.random_vec(m_pre_master, 48);	54✔
169	m_pre_master[0] = offered_version.major_version();	54✔
170	m_pre_master[1] = offered_version.minor_version();	54✔
171
172	PK_Encryptor_EME encryptor(*rsa_pub, rng, "PKCS1v15");	54✔
173
174	const std::vector<uint8_t> encrypted_key = encryptor.encrypt(m_pre_master, rng);	54✔
175
176	append_tls_length_value(m_key_material, encrypted_key, 2);	108✔
177	} else {	54✔
178	throw TLS_Exception(Alert::HandshakeFailure,	×
179	"Expected a RSA key in server cert but got " + server_public_key->algo_name());	×
180	}
181	}
182
183	state.hash().update(io.send(*this));	1,514✔
184	}	765✔
185
186	/*
187	* Read a Client Key Exchange message
188	*/
189	Client_Key_Exchange::Client_Key_Exchange(const std::vector<uint8_t>& contents,	647✔
190	const Handshake_State& state,
191	const Private_Key* server_rsa_kex_key,
192	Credentials_Manager& creds,
193	const Policy& policy,
194	RandomNumberGenerator& rng) {	647✔
195	const Kex_Algo kex_algo = state.ciphersuite().kex_method();	647✔
196
197	if(kex_algo == Kex_Algo::STATIC_RSA) {	647✔
198	BOTAN_ASSERT(state.server_certs() && !state.server_certs()->cert_chain().empty(),	58✔
199	"RSA key exchange negotiated so server sent a certificate");
200
201	if(!server_rsa_kex_key) {	58✔
202	throw Internal_Error("Expected RSA kex but no server kex key set");	×
203	}
204
205	if(server_rsa_kex_key->algo_name() != "RSA") {	58✔
206	throw Internal_Error("Expected RSA key but got " + server_rsa_kex_key->algo_name());	×
207	}
208
209	TLS_Data_Reader reader("ClientKeyExchange", contents);	58✔
210	const std::vector<uint8_t> encrypted_pre_master = reader.get_range<uint8_t>(2, 0, 65535);	58✔
211	reader.assert_done();	58✔
212
213	PK_Decryptor_EME decryptor(*server_rsa_kex_key, rng, "PKCS1v15");	58✔
214
215	const uint8_t client_major = state.client_hello()->legacy_version().major_version();	58✔
216	const uint8_t client_minor = state.client_hello()->legacy_version().minor_version();	58✔
217
218	/*
219	* PK_Decryptor::decrypt_or_random will return a random value if
220	* either the length does not match the expected value or if the
221	* version number embedded in the PMS does not match the one sent
222	* in the client hello.
223	*/
224	const size_t expected_plaintext_size = 48;	58✔
225	const size_t expected_content_size = 2;	58✔
226	const uint8_t expected_content_bytes[expected_content_size] = {client_major, client_minor};	58✔
227	const uint8_t expected_content_pos[expected_content_size] = {0, 1};	58✔
228
229	m_pre_master = decryptor.decrypt_or_random(encrypted_pre_master.data(),	58✔
230	encrypted_pre_master.size(),
231	expected_plaintext_size,
232	rng,
233	expected_content_bytes,
234	expected_content_pos,
235	expected_content_size);	58✔
236	} else {	116✔
237	TLS_Data_Reader reader("ClientKeyExchange", contents);	589✔
238
239	SymmetricKey psk;	589✔
240
241	if(key_exchange_is_psk(kex_algo)) {	589✔
242	m_psk_identity = reader.get_string(2, 0, 65535);	44✔
243
244	psk = creds.psk("tls-server", state.client_hello()->sni_hostname(), m_psk_identity.value());	88✔
245
246	if(psk.length() == 0) {	44✔
247	if(policy.hide_unknown_users()) {	×
248	psk = SymmetricKey(rng, 16);	×
249	} else {
250	throw TLS_Exception(Alert::UnknownPSKIdentity, "No PSK for identifier " + m_psk_identity.value());	×
251	}
252	}
253	}
254
255	if(kex_algo == Kex_Algo::PSK) {	589✔
256	std::vector<uint8_t> zeros(psk.length());	33✔
257	append_tls_length_value(m_pre_master, zeros, 2);	33✔
258	append_tls_length_value(m_pre_master, psk.bits_of(), 2);	99✔
259	} else if(kex_algo == Kex_Algo::DH \|\| kex_algo == Kex_Algo::ECDH \|\| kex_algo == Kex_Algo::ECDHE_PSK) {	589✔
260	const PK_Key_Agreement_Key& ka_key = state.server_kex()->server_kex_key();	556✔
261
262	const std::vector<uint8_t> client_pubkey = (ka_key.algo_name() == "DH")	559✔
263	? reader.get_range<uint8_t>(2, 0, 65535)
264	: reader.get_range<uint8_t>(1, 1, 255);	556✔
265
266	const auto shared_group = state.server_kex()->shared_group();	556✔
267	BOTAN_STATE_CHECK(shared_group && shared_group.value() != Group_Params::NONE);	556✔
268
269	try {	556✔
270	auto shared_secret =	556✔
271	state.callbacks().tls_ephemeral_key_agreement(shared_group.value(), ka_key, client_pubkey, rng, policy);	556✔
272
273	if(ka_key.algo_name() == "DH") {	555✔
274	shared_secret = CT::strip_leading_zeros(shared_secret);	4✔
275	}
276
277	if(kex_algo == Kex_Algo::ECDH \|\| kex_algo == Kex_Algo::ECDHE_PSK) {	555✔
278	// RFC 8422 - 5.11.
279	// With X25519 and X448, a receiving party MUST check whether the
280	// computed premaster secret is the all-zero value and abort the
281	// handshake if so, as described in Section 6 of [RFC7748].
282	BOTAN_ASSERT_NOMSG(state.server_kex()->params().size() >= 3);	551✔
283	Group_Params group = static_cast<Group_Params>(state.server_kex()->params().at(2));	551✔
284	if(group == Group_Params::X25519 && CT::all_zeros(shared_secret.data(), shared_secret.size()).is_set()) {	1,077✔
285	throw TLS_Exception(Alert::DecryptError, "Bad X25519 key exchange");	×
286	}
287	}
288
289	if(kex_algo == Kex_Algo::ECDHE_PSK) {	555✔
290	append_tls_length_value(m_pre_master, shared_secret, 2);	11✔
291	append_tls_length_value(m_pre_master, psk.bits_of(), 2);	33✔
292	} else {
293	m_pre_master = shared_secret;	544✔
294	}
295	} catch(Invalid_Argument& e) {	556✔
296	throw TLS_Exception(Alert::IllegalParameter, e.what());	1✔
297	} catch(TLS_Exception& e) {	1✔
298	// NOLINTNEXTLINE(cert-err60-cpp)
299	throw e;	×
300	} catch(std::exception&) {	×
301	/*
302	* Something failed in the DH/ECDH computation. To avoid possible
303	* attacks which are based on triggering and detecting some edge
304	* failure condition, randomize the pre-master output and carry on,
305	* allowing the protocol to fail later in the finished checks.
306	*/
307	rng.random_vec(m_pre_master, ka_key.public_value().size());	×
308	}	×
309
310	reader.assert_done();	555✔
311	} else {	556✔
312	throw Internal_Error("Client_Key_Exchange: Unknown key exchange negotiated");	×
313	}
314	}	589✔
315	}	649✔
316
317	} // namespace Botan::TLS

randombit / botan / 6421338519

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