11087146043

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/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(!curve_id.is_ecdh_named_curve() && !curve_id.is_x25519() && !curve_id.is_x448()) {
            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 || curve_id == Group_Params::X448) &&
            CT::all_zeros(shared_secret.data(), shared_secret.size()).as_bool()) {
            throw TLS_Exception(Alert::DecryptError, "Bad X25519 or X448 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(curve_id.is_ecdh_named_curve()) {
            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 || group == Group_Params::X448) &&
                  CT::all_zeros(shared_secret.data(), shared_secret.size()).as_bool()) {
                  throw TLS_Exception(Alert::DecryptError, "Bad X25519 or X448 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,	763✔
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) {	763✔
37	const Kex_Algo kex_algo = state.ciphersuite().kex_method();	763✔
38
39	if(kex_algo == Kex_Algo::PSK) {	763✔
40	std::string identity_hint;	43✔
41
42	if(state.server_kex()) {	43✔
43	TLS_Data_Reader reader("ClientKeyExchange", state.server_kex()->params());	27✔
44	identity_hint = reader.get_string(2, 0, 65535);	27✔
45	}
46
47	m_psk_identity = creds.psk_identity("tls-client", std::string(hostname), identity_hint);	86✔
48
49	append_tls_length_value(m_key_material, to_byte_vector(m_psk_identity.value()), 2);	86✔
50
51	SymmetricKey psk = creds.psk("tls-client", std::string(hostname), m_psk_identity.value());	129✔
52
53	std::vector<uint8_t> zeros(psk.length());	43✔
54
55	append_tls_length_value(m_pre_master, zeros, 2);	43✔
56	append_tls_length_value(m_pre_master, psk.bits_of(), 2);	129✔
57	} else if(state.server_kex()) {	806✔
58	TLS_Data_Reader reader("ClientKeyExchange", state.server_kex()->params());	666✔
59
60	SymmetricKey psk;	666✔
61
62	if(kex_algo == Kex_Algo::ECDHE_PSK) {	666✔
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) {	666✔
73	const auto modulus = BigInt::decode(reader.get_range<uint8_t>(2, 1, 65535));	14✔
74	const auto generator = BigInt::decode(reader.get_range<uint8_t>(2, 1, 65535));	10✔
75	const std::vector<uint8_t> peer_public_value = reader.get_range<uint8_t>(2, 1, 65535);	5✔
76
77	if(reader.remaining_bytes()) {	5✔
78	throw Decoding_Error("Bad params size for DH key exchange");	×
79	}
80
81	DL_Group group(modulus, generator);	5✔
82
83	if(!group.verify_group(rng, false)) {	5✔
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);	5✔
88	auto shared_secret = CT::strip_leading_zeros(	5✔
89	state.callbacks().tls_ephemeral_key_agreement(group, *private_key, peer_public_value, rng, policy));	15✔
90
91	if(kex_algo == Kex_Algo::DH) {	5✔
92	m_pre_master = std::move(shared_secret);	5✔
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);	15✔
99	} else if(kex_algo == Kex_Algo::ECDH \|\| kex_algo == Kex_Algo::ECDHE_PSK) {	691✔
100	const uint8_t curve_type = reader.get_byte();	661✔
101	if(curve_type != 3) {	661✔
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());	661✔
106	const std::vector<uint8_t> peer_public_value = reader.get_range<uint8_t>(1, 1, 255);	661✔
107
108	if(!curve_id.is_ecdh_named_curve() && !curve_id.is_x25519() && !curve_id.is_x448()) {	661✔
109	throw TLS_Exception(Alert::HandshakeFailure,	2✔
110	"Server selected a group that is not compatible with the negotiated ciphersuite");	4✔
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);	662✔
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 \|\| curve_id == Group_Params::X448) &&	1,301✔
126	CT::all_zeros(shared_secret.data(), shared_secret.size()).as_bool()) {	1,288✔
127	throw TLS_Exception(Alert::DecryptError, "Bad X25519 or X448 key exchange");	×
128	}
129
130	if(kex_algo == Kex_Algo::ECDH) {	657✔
131	m_pre_master = std::move(shared_secret);	633✔
132	} else {
133	append_tls_length_value(m_pre_master, shared_secret, 2);	24✔
134	append_tls_length_value(m_pre_master, psk.bits_of(), 2);	72✔
135	}
136
137	if(curve_id.is_ecdh_named_curve()) {	657✔
138	auto ecdh_key = dynamic_cast<ECDH_PublicKey*>(private_key.get());	13✔
139	if(!ecdh_key) {	13✔
140	throw TLS_Exception(Alert::InternalError, "Application did not provide a ECDH_PublicKey");	×
141	}
142	append_tls_length_value(m_key_material,	13✔
143	ecdh_key->public_value(state.server_hello()->prefers_compressed_ec_points()	39✔
144	? EC_Point_Format::Compressed
145	: EC_Point_Format::Uncompressed),
146	1);
147	} else {
148	append_tls_length_value(m_key_material, private_key->public_value(), 1);	1,932✔
149	}
150	} else {	1,976✔
151	throw Internal_Error("Client_Key_Exchange: Unknown key exchange method was negotiated");	×
152	}
153
154	reader.assert_done();	662✔
155	} else {	666✔
156	// No server key exchange msg better mean RSA kex + RSA key in cert
157
158	if(kex_algo != Kex_Algo::STATIC_RSA) {	54✔
159	throw Unexpected_Message("No server kex message, but negotiated a key exchange that required it");	×
160	}
161
162	if(!server_public_key) {	54✔
163	throw Internal_Error("No server public key for RSA exchange");	×
164	}
165
166	if(auto rsa_pub = dynamic_cast<const RSA_PublicKey*>(server_public_key)) {	54✔
167	const Protocol_Version offered_version = state.client_hello()->legacy_version();	54✔
168
169	rng.random_vec(m_pre_master, 48);	54✔
170	m_pre_master[0] = offered_version.major_version();	54✔
171	m_pre_master[1] = offered_version.minor_version();	54✔
172
173	PK_Encryptor_EME encryptor(*rsa_pub, rng, "PKCS1v15");	54✔
174
175	const std::vector<uint8_t> encrypted_key = encryptor.encrypt(m_pre_master, rng);	54✔
176
177	append_tls_length_value(m_key_material, encrypted_key, 2);	108✔
178	} else {	54✔
179	throw TLS_Exception(Alert::HandshakeFailure,	×
180	"Expected a RSA key in server cert but got " + server_public_key->algo_name());	×
181	}
182	}
183
184	state.hash().update(io.send(*this));	1,518✔
185	}	763✔
186
187	/*
188	* Read a Client Key Exchange message
189	*/
190	Client_Key_Exchange::Client_Key_Exchange(const std::vector<uint8_t>& contents,	649✔
191	const Handshake_State& state,
192	const Private_Key* server_rsa_kex_key,
193	Credentials_Manager& creds,
194	const Policy& policy,
195	RandomNumberGenerator& rng) {	649✔
196	const Kex_Algo kex_algo = state.ciphersuite().kex_method();	649✔
197
198	if(kex_algo == Kex_Algo::STATIC_RSA) {	649✔
199	BOTAN_ASSERT(state.server_certs() && !state.server_certs()->cert_chain().empty(),	58✔
200	"RSA key exchange negotiated so server sent a certificate");
201
202	if(!server_rsa_kex_key) {	58✔
203	throw Internal_Error("Expected RSA kex but no server kex key set");	×
204	}
205
206	if(server_rsa_kex_key->algo_name() != "RSA") {	58✔
207	throw Internal_Error("Expected RSA key but got " + server_rsa_kex_key->algo_name());	×
208	}
209
210	TLS_Data_Reader reader("ClientKeyExchange", contents);	58✔
211	const std::vector<uint8_t> encrypted_pre_master = reader.get_range<uint8_t>(2, 0, 65535);	58✔
212	reader.assert_done();	58✔
213
214	PK_Decryptor_EME decryptor(*server_rsa_kex_key, rng, "PKCS1v15");	58✔
215
216	const uint8_t client_major = state.client_hello()->legacy_version().major_version();	58✔
217	const uint8_t client_minor = state.client_hello()->legacy_version().minor_version();	58✔
218
219	/*
220	* PK_Decryptor::decrypt_or_random will return a random value if
221	* either the length does not match the expected value or if the
222	* version number embedded in the PMS does not match the one sent
223	* in the client hello.
224	*/
225	const size_t expected_plaintext_size = 48;	58✔
226	const size_t expected_content_size = 2;	58✔
227	const uint8_t expected_content_bytes[expected_content_size] = {client_major, client_minor};	58✔
228	const uint8_t expected_content_pos[expected_content_size] = {0, 1};	58✔
229
230	m_pre_master = decryptor.decrypt_or_random(encrypted_pre_master.data(),	58✔
231	encrypted_pre_master.size(),
232	expected_plaintext_size,
233	rng,
234	expected_content_bytes,
235	expected_content_pos,
236	expected_content_size);	58✔
237	} else {	116✔
238	TLS_Data_Reader reader("ClientKeyExchange", contents);	591✔
239
240	SymmetricKey psk;	591✔
241
242	if(key_exchange_is_psk(kex_algo)) {	591✔
243	m_psk_identity = reader.get_string(2, 0, 65535);	45✔
244
245	psk = creds.psk("tls-server", state.client_hello()->sni_hostname(), m_psk_identity.value());	90✔
246
247	if(psk.length() == 0) {	45✔
248	if(policy.hide_unknown_users()) {	×
249	psk = SymmetricKey(rng, 16);	×
250	} else {
251	throw TLS_Exception(Alert::UnknownPSKIdentity, "No PSK for identifier " + m_psk_identity.value());	×
252	}
253	}
254	}
255
256	if(kex_algo == Kex_Algo::PSK) {	591✔
257	std::vector<uint8_t> zeros(psk.length());	34✔
258	append_tls_length_value(m_pre_master, zeros, 2);	34✔
259	append_tls_length_value(m_pre_master, psk.bits_of(), 2);	102✔
260	} else if(kex_algo == Kex_Algo::DH \|\| kex_algo == Kex_Algo::ECDH \|\| kex_algo == Kex_Algo::ECDHE_PSK) {	591✔
261	const PK_Key_Agreement_Key& ka_key = state.server_kex()->server_kex_key();	557✔
262
263	const std::vector<uint8_t> client_pubkey = (ka_key.algo_name() == "DH")	560✔
264	? reader.get_range<uint8_t>(2, 0, 65535)
265	: reader.get_range<uint8_t>(1, 1, 255);	557✔
266
267	const auto shared_group = state.server_kex()->shared_group();	557✔
268	BOTAN_STATE_CHECK(shared_group && shared_group.value() != Group_Params::NONE);	557✔
269
270	try {	557✔
271	auto shared_secret =	557✔
272	state.callbacks().tls_ephemeral_key_agreement(shared_group.value(), ka_key, client_pubkey, rng, policy);	557✔
273
274	if(ka_key.algo_name() == "DH") {	556✔
275	shared_secret = CT::strip_leading_zeros(shared_secret);	5✔
276	}
277
278	if(kex_algo == Kex_Algo::ECDH \|\| kex_algo == Kex_Algo::ECDHE_PSK) {	556✔
279	// RFC 8422 - 5.11.
280	// With X25519 and X448, a receiving party MUST check whether the
281	// computed premaster secret is the all-zero value and abort the
282	// handshake if so, as described in Section 6 of [RFC7748].
283	BOTAN_ASSERT_NOMSG(state.server_kex()->params().size() >= 3);	551✔
284	Group_Params group = static_cast<Group_Params>(state.server_kex()->params().at(2));	551✔
285	if((group == Group_Params::X25519 \|\| group == Group_Params::X448) &&	1,077✔
286	CT::all_zeros(shared_secret.data(), shared_secret.size()).as_bool()) {	1,052✔
287	throw TLS_Exception(Alert::DecryptError, "Bad X25519 or X448 key exchange");	×
288	}
289	}
290
291	if(kex_algo == Kex_Algo::ECDHE_PSK) {	556✔
292	append_tls_length_value(m_pre_master, shared_secret, 2);	11✔
293	append_tls_length_value(m_pre_master, psk.bits_of(), 2);	33✔
294	} else {
295	m_pre_master = shared_secret;	545✔
296	}
297	} catch(Invalid_Argument& e) {	557✔
298	throw TLS_Exception(Alert::IllegalParameter, e.what());	1✔
299	} catch(TLS_Exception& e) {	1✔
300	// NOLINTNEXTLINE(cert-err60-cpp)
301	throw e;	×
302	} catch(std::exception&) {	×
303	/*
304	* Something failed in the DH/ECDH computation. To avoid possible
305	* attacks which are based on triggering and detecting some edge
306	* failure condition, randomize the pre-master output and carry on,
307	* allowing the protocol to fail later in the finished checks.
308	*/
309	rng.random_vec(m_pre_master, ka_key.public_value().size());	×
310	}	×
311
312	reader.assert_done();	556✔
313	} else {	557✔
314	throw Internal_Error("Client_Key_Exchange: Unknown key exchange negotiated");	×
315	}
316	}	591✔
317	}	651✔
318
319	} // namespace Botan::TLS

randombit / botan / 11087146043

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