6546858227

Committed 17 Oct 2023 12:02PM UTC coverage: 91.71% (+0.002%) from 91.708%

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Merge GH #3760 Move constant time memory comparisons to ct_utils.h

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/src/lib/tls/tls_session.cpp

/*
* TLS Session State
* (C) 2011-2012,2015,2019 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/tls_session.h>

#include <botan/aead.h>
#include <botan/asn1_obj.h>
#include <botan/ber_dec.h>
#include <botan/der_enc.h>
#include <botan/mac.h>
#include <botan/pem.h>
#include <botan/rng.h>
#include <botan/internal/ct_utils.h>
#include <botan/internal/loadstor.h>

#include <botan/tls_callbacks.h>
#include <botan/tls_messages.h>

#include <botan/internal/stl_util.h>

#include <utility>

namespace Botan::TLS {

void Session_Handle::validate_constraints() const {
   std::visit(overloaded{
                 [](const Session_ID& id) {
                    // RFC 5246 7.4.1.2
                    //    opaque SessionID<0..32>;
                    BOTAN_ARG_CHECK(!id.empty(), "Session ID must not be empty");
                    BOTAN_ARG_CHECK(id.size() <= 32, "Session ID cannot be longer than 32 bytes");
                 },
                 [](const Session_Ticket& ticket) {
                    BOTAN_ARG_CHECK(!ticket.empty(), "Ticket most not be empty");
                    BOTAN_ARG_CHECK(ticket.size() <= std::numeric_limits<uint16_t>::max(),
                                    "Ticket cannot be longer than 64kB");
                 },
                 [](const Opaque_Session_Handle& handle) {
                    // RFC 8446 4.6.1
                    //    opaque ticket<1..2^16-1>;
                    BOTAN_ARG_CHECK(!handle.empty(), "Opaque session handle must not be empty");
                    BOTAN_ARG_CHECK(handle.size() <= std::numeric_limits<uint16_t>::max(),
                                    "Opaque session handle cannot be longer than 64kB");
                 },
              },
              m_handle);
}

Opaque_Session_Handle Session_Handle::opaque_handle() const {
   // both a Session_ID and a Session_Ticket could be an Opaque_Session_Handle
   return Opaque_Session_Handle(std::visit([](const auto& handle) { return handle.get(); }, m_handle));
}

std::optional<Session_ID> Session_Handle::id() const {
   if(is_id()) {
      return std::get<Session_ID>(m_handle);
   }

   // Opaque handles can mimick as a Session_ID if they are short enough
   if(is_opaque_handle()) {
      const auto& handle = std::get<Opaque_Session_Handle>(m_handle);
      if(handle.size() <= 32) {
         return Session_ID(handle.get());
      }
   }

   return std::nullopt;
}

std::optional<Session_Ticket> Session_Handle::ticket() const {
   if(is_ticket()) {
      return std::get<Session_Ticket>(m_handle);
   }

   // Opaque handles can mimick 'normal' Session_Tickets at any time
   if(is_opaque_handle()) {
      return Session_Ticket(std::get<Opaque_Session_Handle>(m_handle).get());
   }

   return std::nullopt;
}

Ciphersuite Session_Base::ciphersuite() const {
   auto suite = Ciphersuite::by_id(m_ciphersuite);
   if(!suite.has_value()) {
      throw Decoding_Error("Failed to find cipher suite for ID " + std::to_string(m_ciphersuite));
   }
   return suite.value();
}

Session_Summary::Session_Summary(const Session_Base& base,
                                 bool was_resumption,
                                 std::optional<std::string> psk_identity) :
      Session_Base(base), m_external_psk_identity(std::move(psk_identity)), m_was_resumption(was_resumption) {
   BOTAN_ARG_CHECK(version().is_pre_tls_13(), "Instantiated a TLS 1.2 session summary with an newer TLS version");

   const auto cs = ciphersuite();
   m_kex_algo = cs.kex_algo();
}

#if defined(BOTAN_HAS_TLS_13)

Session_Summary::Session_Summary(const Server_Hello_13& server_hello,
                                 Connection_Side side,
                                 std::vector<X509_Certificate> peer_certs,
                                 std::optional<std::string> psk_identity,
                                 bool session_was_resumed,
                                 Server_Information server_info,
                                 std::chrono::system_clock::time_point current_timestamp) :
      Session_Base(current_timestamp,
                   server_hello.selected_version(),
                   server_hello.ciphersuite(),
                   side,

                   // TODO: SRTP might become necessary when DTLS 1.3 is being implemented
                   0,

                   // RFC 8446 Appendix D
                   //    Because TLS 1.3 always hashes in the transcript up to the server
                   //    Finished, implementations which support both TLS 1.3 and earlier
                   //    versions SHOULD indicate the use of the Extended Master Secret
                   //    extension in their APIs whenever TLS 1.3 is used.
                   true,

                   // TLS 1.3 uses AEADs, so technically encrypt-then-MAC is not applicable.
                   false,
                   std::move(peer_certs),
                   std::move(server_info)),
      m_external_psk_identity(std::move(psk_identity)),
      m_was_resumption(session_was_resumed) {
   BOTAN_ARG_CHECK(version().is_tls_13_or_later(), "Instantiated a TLS 1.3 session summary with an older TLS version");
   set_session_id(server_hello.session_id());

   // In TLS 1.3 the key exchange algorithm is not negotiated in the ciphersuite
   // anymore. This provides a compatible identifier for applications to use.
   m_kex_algo = kex_method_to_string([&] {
      if(psk_used() || was_resumption()) {
         if(const auto keyshare = server_hello.extensions().get<Key_Share>()) {
            const auto group = keyshare->selected_group();
            if(group.is_dh_named_group()) {
               return Kex_Algo::DHE_PSK;
            } else if(group.is_ecdh_named_curve() || group.is_x25519()) {
               return Kex_Algo::ECDHE_PSK;
            } else if(group.is_pure_kyber()) {
               return Kex_Algo::KEM_PSK;
            } else if(group.is_pqc_hybrid()) {
               return Kex_Algo::HYBRID_PSK;
            }
         } else {
            return Kex_Algo::PSK;
         }
      } else {
         const auto keyshare = server_hello.extensions().get<Key_Share>();
         BOTAN_ASSERT_NONNULL(keyshare);
         const auto group = keyshare->selected_group();
         if(group.is_dh_named_group()) {
            return Kex_Algo::DH;
         } else if(group.is_ecdh_named_curve() || group.is_x25519()) {
            return Kex_Algo::ECDH;
         } else if(group.is_pure_kyber()) {
            return Kex_Algo::KEM;
         } else if(group.is_pqc_hybrid()) {
            return Kex_Algo::HYBRID;
         }
      }

      return Kex_Algo::UNDEFINED;
   }());
}

#endif

Session::Session(const secure_vector<uint8_t>& master_secret,
                 Protocol_Version version,
                 uint16_t ciphersuite,
                 Connection_Side side,
                 bool extended_master_secret,
                 bool encrypt_then_mac,
                 const std::vector<X509_Certificate>& certs,
                 const Server_Information& server_info,
                 uint16_t srtp_profile,
                 std::chrono::system_clock::time_point current_timestamp,
                 std::chrono::seconds lifetime_hint) :
      Session_Base(current_timestamp,
                   version,
                   ciphersuite,
                   side,
                   srtp_profile,
                   extended_master_secret,
                   encrypt_then_mac,
                   certs,
                   server_info),
      m_master_secret(master_secret),
      m_early_data_allowed(false),
      m_max_early_data_bytes(0),
      m_ticket_age_add(0),
      m_lifetime_hint(lifetime_hint) {
   BOTAN_ARG_CHECK(version.is_pre_tls_13(), "Instantiated a TLS 1.2 session object with a TLS version newer than 1.2");
}

#if defined(BOTAN_HAS_TLS_13)

Session::Session(const secure_vector<uint8_t>& session_psk,
                 const std::optional<uint32_t>& max_early_data_bytes,
                 uint32_t ticket_age_add,
                 std::chrono::seconds lifetime_hint,
                 Protocol_Version version,
                 uint16_t ciphersuite,
                 Connection_Side side,
                 const std::vector<X509_Certificate>& peer_certs,
                 const Server_Information& server_info,
                 std::chrono::system_clock::time_point current_timestamp) :
      Session_Base(current_timestamp,
                   version,
                   ciphersuite,
                   side,

                   // TODO: SRTP might become necessary when DTLS 1.3 is being implemented
                   0,

                   // RFC 8446 Appendix D
                   //    Because TLS 1.3 always hashes in the transcript up to the server
                   //    Finished, implementations which support both TLS 1.3 and earlier
                   //    versions SHOULD indicate the use of the Extended Master Secret
                   //    extension in their APIs whenever TLS 1.3 is used.
                   true,

                   // TLS 1.3 uses AEADs, so technically encrypt-then-MAC is not applicable.
                   false,
                   peer_certs,
                   server_info),
      m_master_secret(session_psk),
      m_early_data_allowed(max_early_data_bytes.has_value()),
      m_max_early_data_bytes(max_early_data_bytes.value_or(0)),
      m_ticket_age_add(ticket_age_add),
      m_lifetime_hint(lifetime_hint) {
   BOTAN_ARG_CHECK(!version.is_pre_tls_13(), "Instantiated a TLS 1.3 session object with a TLS version older than 1.3");
}

Session::Session(secure_vector<uint8_t>&& session_psk,
                 const std::optional<uint32_t>& max_early_data_bytes,
                 std::chrono::seconds lifetime_hint,
                 const std::vector<X509_Certificate>& peer_certs,
                 const Client_Hello_13& client_hello,
                 const Server_Hello_13& server_hello,
                 Callbacks& callbacks,
                 RandomNumberGenerator& rng) :
      Session_Base(callbacks.tls_current_timestamp(),
                   server_hello.selected_version(),
                   server_hello.ciphersuite(),
                   Connection_Side::Server,
                   0,
                   true,
                   false,  // see constructor above for rationales
                   peer_certs,
                   Server_Information(client_hello.sni_hostname())),
      m_master_secret(std::move(session_psk)),
      m_early_data_allowed(max_early_data_bytes.has_value()),
      m_max_early_data_bytes(max_early_data_bytes.value_or(0)),
      m_ticket_age_add(load_be<uint32_t>(rng.random_vec(4).data(), 0)),
      m_lifetime_hint(lifetime_hint) {
   BOTAN_ARG_CHECK(!m_version.is_pre_tls_13(),
                   "Instantiated a TLS 1.3 session object with a TLS version older than 1.3");
}

#endif

Session::Session(std::string_view pem) : Session(PEM_Code::decode_check_label(pem, "TLS SESSION")) {}

Session::Session(std::span<const uint8_t> ber_data) {
   uint8_t side_code = 0;

   ASN1_String server_hostname;
   ASN1_String server_service;
   size_t server_port;

   uint8_t major_version = 0, minor_version = 0;

   size_t start_time = 0;
   size_t srtp_profile = 0;
   uint16_t ciphersuite_code = 0;
   uint64_t lifetime_hint = 0;

   BER_Decoder(ber_data.data(), ber_data.size())
      .start_sequence()
      .decode_and_check(static_cast<size_t>(TLS_SESSION_PARAM_STRUCT_VERSION),
                        "Unknown version in serialized TLS session")
      .decode_integer_type(start_time)
      .decode_integer_type(major_version)
      .decode_integer_type(minor_version)
      .decode_integer_type(ciphersuite_code)
      .decode_integer_type(side_code)
      .decode(m_extended_master_secret)
      .decode(m_encrypt_then_mac)
      .decode(m_master_secret, ASN1_Type::OctetString)
      .decode_list<X509_Certificate>(m_peer_certs)
      .decode(server_hostname)
      .decode(server_service)
      .decode(server_port)
      .decode(srtp_profile)
      .decode(m_early_data_allowed)
      .decode_integer_type(m_max_early_data_bytes)
      .decode_integer_type(m_ticket_age_add)
      .decode_integer_type(lifetime_hint)
      .end_cons()
      .verify_end();

   if(!Ciphersuite::by_id(ciphersuite_code)) {
      throw Decoding_Error(
         "Serialized TLS session contains unknown cipher suite "
         "(" +
         std::to_string(ciphersuite_code) + ")");
   }

   m_ciphersuite = ciphersuite_code;
   m_version = Protocol_Version(major_version, minor_version);
   m_start_time = std::chrono::system_clock::from_time_t(start_time);
   m_connection_side = static_cast<Connection_Side>(side_code);
   m_srtp_profile = static_cast<uint16_t>(srtp_profile);

   m_server_info =
      Server_Information(server_hostname.value(), server_service.value(), static_cast<uint16_t>(server_port));

   m_lifetime_hint = std::chrono::seconds(lifetime_hint);
}

secure_vector<uint8_t> Session::DER_encode() const {
   return DER_Encoder()
      .start_sequence()
      .encode(static_cast<size_t>(TLS_SESSION_PARAM_STRUCT_VERSION))
      .encode(static_cast<size_t>(std::chrono::system_clock::to_time_t(m_start_time)))
      .encode(static_cast<size_t>(m_version.major_version()))
      .encode(static_cast<size_t>(m_version.minor_version()))
      .encode(static_cast<size_t>(m_ciphersuite))
      .encode(static_cast<size_t>(m_connection_side))
      .encode(m_extended_master_secret)
      .encode(m_encrypt_then_mac)
      .encode(m_master_secret, ASN1_Type::OctetString)
      .start_sequence()
      .encode_list(m_peer_certs)
      .end_cons()
      .encode(ASN1_String(m_server_info.hostname(), ASN1_Type::Utf8String))
      .encode(ASN1_String(m_server_info.service(), ASN1_Type::Utf8String))
      .encode(static_cast<size_t>(m_server_info.port()))
      .encode(static_cast<size_t>(m_srtp_profile))

      // the fields below were introduced for TLS 1.3 session tickets
      .encode(m_early_data_allowed)
      .encode(static_cast<size_t>(m_max_early_data_bytes))
      .encode(static_cast<size_t>(m_ticket_age_add))
      .encode(static_cast<size_t>(m_lifetime_hint.count()))
      .end_cons()
      .get_contents();
}

std::string Session::PEM_encode() const {
   return PEM_Code::encode(this->DER_encode(), "TLS SESSION");
}

secure_vector<uint8_t> Session::extract_master_secret() {
   BOTAN_STATE_CHECK(!m_master_secret.empty());
   return std::exchange(m_master_secret, {});
}

namespace {

// The output length of the HMAC must be a valid keylength for the AEAD
const char* const TLS_SESSION_CRYPT_HMAC = "HMAC(SHA-512-256)";
// SIV would be better, but we can't assume it is available
const char* const TLS_SESSION_CRYPT_AEAD = "AES-256/GCM";
const char* const TLS_SESSION_CRYPT_KEY_NAME = "BOTAN TLS SESSION KEY NAME";
const uint64_t TLS_SESSION_CRYPT_MAGIC = 0x068B5A9D396C0000;
const size_t TLS_SESSION_CRYPT_MAGIC_LEN = 8;
const size_t TLS_SESSION_CRYPT_KEY_NAME_LEN = 4;
const size_t TLS_SESSION_CRYPT_AEAD_NONCE_LEN = 12;
const size_t TLS_SESSION_CRYPT_AEAD_KEY_SEED_LEN = 16;
const size_t TLS_SESSION_CRYPT_AEAD_TAG_SIZE = 16;

const size_t TLS_SESSION_CRYPT_HDR_LEN = TLS_SESSION_CRYPT_MAGIC_LEN + TLS_SESSION_CRYPT_KEY_NAME_LEN +
                                         TLS_SESSION_CRYPT_AEAD_NONCE_LEN + TLS_SESSION_CRYPT_AEAD_KEY_SEED_LEN;

const size_t TLS_SESSION_CRYPT_OVERHEAD = TLS_SESSION_CRYPT_HDR_LEN + TLS_SESSION_CRYPT_AEAD_TAG_SIZE;

}  // namespace

std::vector<uint8_t> Session::encrypt(const SymmetricKey& key, RandomNumberGenerator& rng) const {
   auto hmac = MessageAuthenticationCode::create_or_throw(TLS_SESSION_CRYPT_HMAC);
   hmac->set_key(key);

   // First derive the "key name"
   std::vector<uint8_t> key_name(hmac->output_length());
   hmac->update(TLS_SESSION_CRYPT_KEY_NAME);
   hmac->final(key_name.data());
   key_name.resize(TLS_SESSION_CRYPT_KEY_NAME_LEN);

   std::vector<uint8_t> aead_nonce;
   std::vector<uint8_t> key_seed;

   rng.random_vec(aead_nonce, TLS_SESSION_CRYPT_AEAD_NONCE_LEN);
   rng.random_vec(key_seed, TLS_SESSION_CRYPT_AEAD_KEY_SEED_LEN);

   hmac->update(key_seed);
   const secure_vector<uint8_t> aead_key = hmac->final();

   secure_vector<uint8_t> bits = this->DER_encode();

   // create the header
   std::vector<uint8_t> buf;
   buf.reserve(TLS_SESSION_CRYPT_OVERHEAD + bits.size());
   buf.resize(TLS_SESSION_CRYPT_MAGIC_LEN);
   store_be(TLS_SESSION_CRYPT_MAGIC, &buf[0]);
   buf += key_name;
   buf += key_seed;
   buf += aead_nonce;

   auto aead = AEAD_Mode::create_or_throw(TLS_SESSION_CRYPT_AEAD, Cipher_Dir::Encryption);
   BOTAN_ASSERT_NOMSG(aead->valid_nonce_length(TLS_SESSION_CRYPT_AEAD_NONCE_LEN));
   BOTAN_ASSERT_NOMSG(aead->tag_size() == TLS_SESSION_CRYPT_AEAD_TAG_SIZE);
   aead->set_key(aead_key);
   aead->set_associated_data(buf);
   aead->start(aead_nonce);
   aead->finish(bits, 0);

   // append the ciphertext
   buf += bits;
   return buf;
}

Session Session::decrypt(std::span<const uint8_t> in, const SymmetricKey& key) {
   try {
      const size_t min_session_size = 48 + 4;  // serious under-estimate
      if(in.size() < TLS_SESSION_CRYPT_OVERHEAD + min_session_size) {
         throw Decoding_Error("Encrypted session too short to be valid");
      }

      BufferSlicer sub(in);
      const auto magic = sub.take(TLS_SESSION_CRYPT_MAGIC_LEN).data();
      const auto key_name = sub.take(TLS_SESSION_CRYPT_KEY_NAME_LEN).data();
      const auto key_seed = sub.take(TLS_SESSION_CRYPT_AEAD_KEY_SEED_LEN).data();
      const auto aead_nonce = sub.take(TLS_SESSION_CRYPT_AEAD_NONCE_LEN).data();
      auto ctext = sub.copy_as_secure_vector(sub.remaining());

      if(load_be<uint64_t>(magic, 0) != TLS_SESSION_CRYPT_MAGIC) {
         throw Decoding_Error("Missing expected magic numbers");
      }

      auto hmac = MessageAuthenticationCode::create_or_throw(TLS_SESSION_CRYPT_HMAC);
      hmac->set_key(key);

      // First derive and check the "key name"
      std::vector<uint8_t> cmp_key_name(hmac->output_length());
      hmac->update(TLS_SESSION_CRYPT_KEY_NAME);
      hmac->final(cmp_key_name.data());

      if(CT::is_equal(cmp_key_name.data(), key_name, TLS_SESSION_CRYPT_KEY_NAME_LEN).as_bool() == false) {
         throw Decoding_Error("Wrong key name for encrypted session");
      }

      hmac->update(key_seed, TLS_SESSION_CRYPT_AEAD_KEY_SEED_LEN);
      const secure_vector<uint8_t> aead_key = hmac->final();

      auto aead = AEAD_Mode::create_or_throw(TLS_SESSION_CRYPT_AEAD, Cipher_Dir::Decryption);
      aead->set_key(aead_key);
      aead->set_associated_data(in.data(), TLS_SESSION_CRYPT_HDR_LEN);
      aead->start(aead_nonce, TLS_SESSION_CRYPT_AEAD_NONCE_LEN);
      aead->finish(ctext, 0);
      return Session(ctext);
   } catch(std::exception& e) {
      throw Decoding_Error("Failed to decrypt serialized TLS session: " + std::string(e.what()));
   }
}

}  // namespace Botan::TLS

1	/*
2	* TLS Session State
3	* (C) 2011-2012,2015,2019 Jack Lloyd
4	*
5	* Botan is released under the Simplified BSD License (see license.txt)
6	*/
7
8	#include <botan/tls_session.h>
9
10	#include <botan/aead.h>
11	#include <botan/asn1_obj.h>
12	#include <botan/ber_dec.h>
13	#include <botan/der_enc.h>
14	#include <botan/mac.h>
15	#include <botan/pem.h>
16	#include <botan/rng.h>
17	#include <botan/internal/ct_utils.h>
18	#include <botan/internal/loadstor.h>
19
20	#include <botan/tls_callbacks.h>
21	#include <botan/tls_messages.h>
22
23	#include <botan/internal/stl_util.h>
24
25	#include <utility>
26
27	namespace Botan::TLS {
28
29	void Session_Handle::validate_constraints() const {	3,457✔
30	std::visit(overloaded{	6,914✔
31	[](const Session_ID& id) {	636✔
32	// RFC 5246 7.4.1.2
33	// opaque SessionID<0..32>;
34	BOTAN_ARG_CHECK(!id.empty(), "Session ID must not be empty");	636✔
35	BOTAN_ARG_CHECK(id.size() <= 32, "Session ID cannot be longer than 32 bytes");	636✔
36	},	636✔
37	[](const Session_Ticket& ticket) {	2,132✔
38	BOTAN_ARG_CHECK(!ticket.empty(), "Ticket most not be empty");	2,132✔
39	BOTAN_ARG_CHECK(ticket.size() <= std::numeric_limits<uint16_t>::max(),	2,132✔
40	"Ticket cannot be longer than 64kB");
41	},	2,132✔
42	[](const Opaque_Session_Handle& handle) {	689✔
43	// RFC 8446 4.6.1
44	// opaque ticket<1..2^16-1>;
45	BOTAN_ARG_CHECK(!handle.empty(), "Opaque session handle must not be empty");	689✔
46	BOTAN_ARG_CHECK(handle.size() <= std::numeric_limits<uint16_t>::max(),	689✔
47	"Opaque session handle cannot be longer than 64kB");
48	},	689✔
49	},
50	m_handle);	3,457✔
51	}	3,457✔
52
53	Opaque_Session_Handle Session_Handle::opaque_handle() const {	366✔
54	// both a Session_ID and a Session_Ticket could be an Opaque_Session_Handle
55	return Opaque_Session_Handle(std::visit([](const auto& handle) { return handle.get(); }, m_handle));	732✔
56	}
57
58	std::optional<Session_ID> Session_Handle::id() const {	2,395✔
59	if(is_id()) {	2,395✔
60	return std::get<Session_ID>(m_handle);	581✔
61	}
62
63	// Opaque handles can mimick as a Session_ID if they are short enough
64	if(is_opaque_handle()) {	1,814✔
65	const auto& handle = std::get<Opaque_Session_Handle>(m_handle);	680✔
66	if(handle.size() <= 32) {	680✔
67	return Session_ID(handle.get());	26✔
68	}
69	}
70
71	return std::nullopt;	1,788✔
72	}
73
74	std::optional<Session_Ticket> Session_Handle::ticket() const {	1,710✔
75	if(is_ticket()) {	1,710✔
76	return std::get<Session_Ticket>(m_handle);	1,205✔
77	}
78
79	// Opaque handles can mimick 'normal' Session_Tickets at any time
80	if(is_opaque_handle()) {	505✔
81	return Session_Ticket(std::get<Opaque_Session_Handle>(m_handle).get());	216✔
82	}
83
84	return std::nullopt;	289✔
85	}
86
87	Ciphersuite Session_Base::ciphersuite() const {	4,804✔
88	auto suite = Ciphersuite::by_id(m_ciphersuite);	4,804✔
89	if(!suite.has_value()) {	4,804✔
90	throw Decoding_Error("Failed to find cipher suite for ID " + std::to_string(m_ciphersuite));	×
91	}
92	return suite.value();	4,804✔
93	}
94
95	Session_Summary::Session_Summary(const Session_Base& base,	1,734✔
96	bool was_resumption,
97	std::optional<std::string> psk_identity) :	1,734✔
98	Session_Base(base), m_external_psk_identity(std::move(psk_identity)), m_was_resumption(was_resumption) {	1,846✔
99	BOTAN_ARG_CHECK(version().is_pre_tls_13(), "Instantiated a TLS 1.2 session summary with an newer TLS version");	1,734✔
100
101	const auto cs = ciphersuite();	1,734✔
102	m_kex_algo = cs.kex_algo();	1,734✔
103	}	1,734✔
104
105	#if defined(BOTAN_HAS_TLS_13)
106
107	Session_Summary::Session_Summary(const Server_Hello_13& server_hello,	600✔
108	Connection_Side side,
109	std::vector<X509_Certificate> peer_certs,
110	std::optional<std::string> psk_identity,
111	bool session_was_resumed,
112	Server_Information server_info,
113	std::chrono::system_clock::time_point current_timestamp) :	600✔
114	Session_Base(current_timestamp,
115	server_hello.selected_version(),
116	server_hello.ciphersuite(),	600✔
117	side,
118
119	// TODO: SRTP might become necessary when DTLS 1.3 is being implemented
120	0,
121
122	// RFC 8446 Appendix D
123	// Because TLS 1.3 always hashes in the transcript up to the server
124	// Finished, implementations which support both TLS 1.3 and earlier
125	// versions SHOULD indicate the use of the Extended Master Secret
126	// extension in their APIs whenever TLS 1.3 is used.
127	true,
128
129	// TLS 1.3 uses AEADs, so technically encrypt-then-MAC is not applicable.
130	false,
131	std::move(peer_certs),	600✔
132	std::move(server_info)),	600✔
133	m_external_psk_identity(std::move(psk_identity)),	600✔
134	m_was_resumption(session_was_resumed) {	1,204✔
135	BOTAN_ARG_CHECK(version().is_tls_13_or_later(), "Instantiated a TLS 1.3 session summary with an older TLS version");	600✔
136	set_session_id(server_hello.session_id());	1,200✔
137
138	// In TLS 1.3 the key exchange algorithm is not negotiated in the ciphersuite
139	// anymore. This provides a compatible identifier for applications to use.
140	m_kex_algo = kex_method_to_string([&] {	600✔
141	if(psk_used() \|\| was_resumption()) {	600✔
142	if(const auto keyshare = server_hello.extensions().get<Key_Share>()) {	165✔
143	const auto group = keyshare->selected_group();	165✔
144	if(group.is_dh_named_group()) {	165✔
145	return Kex_Algo::DHE_PSK;	165✔
146	} else if(group.is_ecdh_named_curve() \|\| group.is_x25519()) {	165✔
147	return Kex_Algo::ECDHE_PSK;
148	} else if(group.is_pure_kyber()) {	165✔
149	return Kex_Algo::KEM_PSK;
150	} else if(group.is_pqc_hybrid()) {	×
151	return Kex_Algo::HYBRID_PSK;
152	}
153	} else {
154	return Kex_Algo::PSK;
155	}
156	} else {
157	const auto keyshare = server_hello.extensions().get<Key_Share>();	435✔
158	BOTAN_ASSERT_NONNULL(keyshare);	435✔
159	const auto group = keyshare->selected_group();	435✔
160	if(group.is_dh_named_group()) {	435✔
161	return Kex_Algo::DH;	435✔
162	} else if(group.is_ecdh_named_curve() \|\| group.is_x25519()) {	435✔
163	return Kex_Algo::ECDH;
164	} else if(group.is_pure_kyber()) {	440✔
165	return Kex_Algo::KEM;
166	} else if(group.is_pqc_hybrid()) {	5✔
167	return Kex_Algo::HYBRID;
168	}
169	}
170
171	return Kex_Algo::UNDEFINED;
172	}());	600✔
173	}	600✔
174
175	#endif
176
177	Session::Session(const secure_vector<uint8_t>& master_secret,	1,616✔
178	Protocol_Version version,
179	uint16_t ciphersuite,
180	Connection_Side side,
181	bool extended_master_secret,
182	bool encrypt_then_mac,
183	const std::vector<X509_Certificate>& certs,
184	const Server_Information& server_info,
185	uint16_t srtp_profile,
186	std::chrono::system_clock::time_point current_timestamp,
187	std::chrono::seconds lifetime_hint) :	1,616✔
188	Session_Base(current_timestamp,
189	version,
190	ciphersuite,
191	side,
192	srtp_profile,
193	extended_master_secret,
194	encrypt_then_mac,
195	certs,
196	server_info),
197	m_master_secret(master_secret),	1,616✔
198	m_early_data_allowed(false),	1,616✔
199	m_max_early_data_bytes(0),	1,616✔
200	m_ticket_age_add(0),	1,616✔
201	m_lifetime_hint(lifetime_hint) {	1,616✔
202	BOTAN_ARG_CHECK(version.is_pre_tls_13(), "Instantiated a TLS 1.2 session object with a TLS version newer than 1.2");	1,616✔
203	}	1,616✔
204
205	#if defined(BOTAN_HAS_TLS_13)
206
207	Session::Session(const secure_vector<uint8_t>& session_psk,	575✔
208	const std::optional<uint32_t>& max_early_data_bytes,
209	uint32_t ticket_age_add,
210	std::chrono::seconds lifetime_hint,
211	Protocol_Version version,
212	uint16_t ciphersuite,
213	Connection_Side side,
214	const std::vector<X509_Certificate>& peer_certs,
215	const Server_Information& server_info,
216	std::chrono::system_clock::time_point current_timestamp) :	575✔
217	Session_Base(current_timestamp,
218	version,
219	ciphersuite,
220	side,
221
222	// TODO: SRTP might become necessary when DTLS 1.3 is being implemented
223	0,
224
225	// RFC 8446 Appendix D
226	// Because TLS 1.3 always hashes in the transcript up to the server
227	// Finished, implementations which support both TLS 1.3 and earlier
228	// versions SHOULD indicate the use of the Extended Master Secret
229	// extension in their APIs whenever TLS 1.3 is used.
230	true,
231
232	// TLS 1.3 uses AEADs, so technically encrypt-then-MAC is not applicable.
233	false,
234	peer_certs,
235	server_info),
236	m_master_secret(session_psk),	575✔
237	m_early_data_allowed(max_early_data_bytes.has_value()),	575✔
238	m_max_early_data_bytes(max_early_data_bytes.value_or(0)),	575✔
239	m_ticket_age_add(ticket_age_add),	575✔
240	m_lifetime_hint(lifetime_hint) {	575✔
241	BOTAN_ARG_CHECK(!version.is_pre_tls_13(), "Instantiated a TLS 1.3 session object with a TLS version older than 1.3");	575✔
242	}	575✔
243
244	Session::Session(secure_vector<uint8_t>&& session_psk,	280✔
245	const std::optional<uint32_t>& max_early_data_bytes,
246	std::chrono::seconds lifetime_hint,
247	const std::vector<X509_Certificate>& peer_certs,
248	const Client_Hello_13& client_hello,
249	const Server_Hello_13& server_hello,
250	Callbacks& callbacks,
251	RandomNumberGenerator& rng) :	280✔
252	Session_Base(callbacks.tls_current_timestamp(),	280✔
253	server_hello.selected_version(),
254	server_hello.ciphersuite(),	280✔
255	Connection_Side::Server,
256	0,
257	true,
258	false, // see constructor above for rationales
259	peer_certs,
260	Server_Information(client_hello.sni_hostname())),	560✔
261	m_master_secret(std::move(session_psk)),	280✔
262	m_early_data_allowed(max_early_data_bytes.has_value()),	280✔
263	m_max_early_data_bytes(max_early_data_bytes.value_or(0)),	280✔
264	m_ticket_age_add(load_be<uint32_t>(rng.random_vec(4).data(), 0)),	280✔
265	m_lifetime_hint(lifetime_hint) {	840✔
266	BOTAN_ARG_CHECK(!m_version.is_pre_tls_13(),	280✔
267	"Instantiated a TLS 1.3 session object with a TLS version older than 1.3");
268	}	280✔
269
270	#endif
271
272	Session::Session(std::string_view pem) : Session(PEM_Code::decode_check_label(pem, "TLS SESSION")) {}	3✔
273
274	Session::Session(std::span<const uint8_t> ber_data) {	452✔
275	uint8_t side_code = 0;	452✔
276
277	ASN1_String server_hostname;	452✔
278	ASN1_String server_service;	452✔
279	size_t server_port;	452✔
280
281	uint8_t major_version = 0, minor_version = 0;	452✔
282
283	size_t start_time = 0;	452✔
284	size_t srtp_profile = 0;	452✔
285	uint16_t ciphersuite_code = 0;	452✔
286	uint64_t lifetime_hint = 0;	452✔
287
288	BER_Decoder(ber_data.data(), ber_data.size())	452✔
289	.start_sequence()	904✔
290	.decode_and_check(static_cast<size_t>(TLS_SESSION_PARAM_STRUCT_VERSION),	904✔
291	"Unknown version in serialized TLS session")
292	.decode_integer_type(start_time)	452✔
293	.decode_integer_type(major_version)	452✔
294	.decode_integer_type(minor_version)	452✔
295	.decode_integer_type(ciphersuite_code)	452✔
296	.decode_integer_type(side_code)	452✔
297	.decode(m_extended_master_secret)	452✔
298	.decode(m_encrypt_then_mac)	452✔
299	.decode(m_master_secret, ASN1_Type::OctetString)	452✔
300	.decode_list<X509_Certificate>(m_peer_certs)	452✔
301	.decode(server_hostname)	452✔
302	.decode(server_service)	452✔
303	.decode(server_port)	452✔
304	.decode(srtp_profile)	452✔
305	.decode(m_early_data_allowed)	452✔
306	.decode_integer_type(m_max_early_data_bytes)	452✔
307	.decode_integer_type(m_ticket_age_add)	452✔
308	.decode_integer_type(lifetime_hint)	452✔
309	.end_cons()	452✔
310	.verify_end();	452✔
311
312	if(!Ciphersuite::by_id(ciphersuite_code)) {	452✔
313	throw Decoding_Error(	1✔
314	"Serialized TLS session contains unknown cipher suite "
315	"(" +	2✔
316	std::to_string(ciphersuite_code) + ")");	4✔
317	}
318
319	m_ciphersuite = ciphersuite_code;	451✔
320	m_version = Protocol_Version(major_version, minor_version);	451✔
321	m_start_time = std::chrono::system_clock::from_time_t(start_time);	451✔
322	m_connection_side = static_cast<Connection_Side>(side_code);	451✔
323	m_srtp_profile = static_cast<uint16_t>(srtp_profile);	451✔
324
325	m_server_info =	451✔
326	Server_Information(server_hostname.value(), server_service.value(), static_cast<uint16_t>(server_port));	902✔
327
328	m_lifetime_hint = std::chrono::seconds(lifetime_hint);	451✔
329	}	455✔
330
331	secure_vector<uint8_t> Session::DER_encode() const {	1,129✔
332	return DER_Encoder()	1,129✔
333	.start_sequence()	1,129✔
334	.encode(static_cast<size_t>(TLS_SESSION_PARAM_STRUCT_VERSION))	1,129✔
335	.encode(static_cast<size_t>(std::chrono::system_clock::to_time_t(m_start_time)))	1,129✔
336	.encode(static_cast<size_t>(m_version.major_version()))	1,129✔
337	.encode(static_cast<size_t>(m_version.minor_version()))	1,129✔
338	.encode(static_cast<size_t>(m_ciphersuite))	1,129✔
339	.encode(static_cast<size_t>(m_connection_side))	1,129✔
340	.encode(m_extended_master_secret)	1,129✔
341	.encode(m_encrypt_then_mac)	1,129✔
342	.encode(m_master_secret, ASN1_Type::OctetString)	1,129✔
343	.start_sequence()	1,503✔
344	.encode_list(m_peer_certs)	1,129✔
345	.end_cons()	1,129✔
346	.encode(ASN1_String(m_server_info.hostname(), ASN1_Type::Utf8String))	3,636✔
347	.encode(ASN1_String(m_server_info.service(), ASN1_Type::Utf8String))	3,387✔
348	.encode(static_cast<size_t>(m_server_info.port()))	1,129✔
349	.encode(static_cast<size_t>(m_srtp_profile))	1,129✔
350
351	// the fields below were introduced for TLS 1.3 session tickets
352	.encode(m_early_data_allowed)	1,129✔
353	.encode(static_cast<size_t>(m_max_early_data_bytes))	1,129✔
354	.encode(static_cast<size_t>(m_ticket_age_add))	1,129✔
355	.encode(static_cast<size_t>(m_lifetime_hint.count()))	1,129✔
356	.end_cons()	1,129✔
357	.get_contents();	2,258✔
358	}
359
360	std::string Session::PEM_encode() const {	2✔
361	return PEM_Code::encode(this->DER_encode(), "TLS SESSION");	6✔
362	}
363
364	secure_vector<uint8_t> Session::extract_master_secret() {	177✔
365	BOTAN_STATE_CHECK(!m_master_secret.empty());	177✔
366	return std::exchange(m_master_secret, {});	177✔
367	}
368
369	namespace {
370
371	// The output length of the HMAC must be a valid keylength for the AEAD
372	const char* const TLS_SESSION_CRYPT_HMAC = "HMAC(SHA-512-256)";
373	// SIV would be better, but we can't assume it is available
374	const char* const TLS_SESSION_CRYPT_AEAD = "AES-256/GCM";
375	const char* const TLS_SESSION_CRYPT_KEY_NAME = "BOTAN TLS SESSION KEY NAME";
376	const uint64_t TLS_SESSION_CRYPT_MAGIC = 0x068B5A9D396C0000;
377	const size_t TLS_SESSION_CRYPT_MAGIC_LEN = 8;
378	const size_t TLS_SESSION_CRYPT_KEY_NAME_LEN = 4;
379	const size_t TLS_SESSION_CRYPT_AEAD_NONCE_LEN = 12;
380	const size_t TLS_SESSION_CRYPT_AEAD_KEY_SEED_LEN = 16;
381	const size_t TLS_SESSION_CRYPT_AEAD_TAG_SIZE = 16;
382
383	const size_t TLS_SESSION_CRYPT_HDR_LEN = TLS_SESSION_CRYPT_MAGIC_LEN + TLS_SESSION_CRYPT_KEY_NAME_LEN +
384	TLS_SESSION_CRYPT_AEAD_NONCE_LEN + TLS_SESSION_CRYPT_AEAD_KEY_SEED_LEN;
385
386	const size_t TLS_SESSION_CRYPT_OVERHEAD = TLS_SESSION_CRYPT_HDR_LEN + TLS_SESSION_CRYPT_AEAD_TAG_SIZE;
387
388	} // namespace
389
390	std::vector<uint8_t> Session::encrypt(const SymmetricKey& key, RandomNumberGenerator& rng) const {	1,121✔
391	auto hmac = MessageAuthenticationCode::create_or_throw(TLS_SESSION_CRYPT_HMAC);	1,121✔
392	hmac->set_key(key);	1,121✔
393
394	// First derive the "key name"
395	std::vector<uint8_t> key_name(hmac->output_length());	1,121✔
396	hmac->update(TLS_SESSION_CRYPT_KEY_NAME);	1,121✔
397	hmac->final(key_name.data());	1,121✔
398	key_name.resize(TLS_SESSION_CRYPT_KEY_NAME_LEN);	1,121✔
399
400	std::vector<uint8_t> aead_nonce;	1,121✔
401	std::vector<uint8_t> key_seed;	1,121✔
402
403	rng.random_vec(aead_nonce, TLS_SESSION_CRYPT_AEAD_NONCE_LEN);	1,121✔
404	rng.random_vec(key_seed, TLS_SESSION_CRYPT_AEAD_KEY_SEED_LEN);	1,121✔
405
406	hmac->update(key_seed);	1,121✔
407	const secure_vector<uint8_t> aead_key = hmac->final();	1,121✔
408
409	secure_vector<uint8_t> bits = this->DER_encode();	1,121✔
410
411	// create the header
412	std::vector<uint8_t> buf;	1,121✔
413	buf.reserve(TLS_SESSION_CRYPT_OVERHEAD + bits.size());	1,121✔
414	buf.resize(TLS_SESSION_CRYPT_MAGIC_LEN);	1,121✔
415	store_be(TLS_SESSION_CRYPT_MAGIC, &buf[0]);	1,121✔
416	buf += key_name;	1,121✔
417	buf += key_seed;	1,121✔
418	buf += aead_nonce;	1,121✔
419
420	auto aead = AEAD_Mode::create_or_throw(TLS_SESSION_CRYPT_AEAD, Cipher_Dir::Encryption);	1,121✔
421	BOTAN_ASSERT_NOMSG(aead->valid_nonce_length(TLS_SESSION_CRYPT_AEAD_NONCE_LEN));	1,121✔
422	BOTAN_ASSERT_NOMSG(aead->tag_size() == TLS_SESSION_CRYPT_AEAD_TAG_SIZE);	1,121✔
423	aead->set_key(aead_key);	1,121✔
424	aead->set_associated_data(buf);	1,121✔
425	aead->start(aead_nonce);	1,121✔
426	aead->finish(bits, 0);	1,121✔
427
428	// append the ciphertext
429	buf += bits;	1,121✔
430	return buf;	1,121✔
431	}	7,847✔
432
433	Session Session::decrypt(std::span<const uint8_t> in, const SymmetricKey& key) {	453✔
434	try {	453✔
435	const size_t min_session_size = 48 + 4; // serious under-estimate	453✔
436	if(in.size() < TLS_SESSION_CRYPT_OVERHEAD + min_session_size) {	453✔
437	throw Decoding_Error("Encrypted session too short to be valid");	3✔
438	}
439
440	BufferSlicer sub(in);	450✔
441	const auto magic = sub.take(TLS_SESSION_CRYPT_MAGIC_LEN).data();	450✔
442	const auto key_name = sub.take(TLS_SESSION_CRYPT_KEY_NAME_LEN).data();	450✔
443	const auto key_seed = sub.take(TLS_SESSION_CRYPT_AEAD_KEY_SEED_LEN).data();	450✔
444	const auto aead_nonce = sub.take(TLS_SESSION_CRYPT_AEAD_NONCE_LEN).data();	450✔
445	auto ctext = sub.copy_as_secure_vector(sub.remaining());	450✔
446
447	if(load_be<uint64_t>(magic, 0) != TLS_SESSION_CRYPT_MAGIC) {	450✔
448	throw Decoding_Error("Missing expected magic numbers");	×
449	}
450
451	auto hmac = MessageAuthenticationCode::create_or_throw(TLS_SESSION_CRYPT_HMAC);	454✔
452	hmac->set_key(key);	450✔
453
454	// First derive and check the "key name"
455	std::vector<uint8_t> cmp_key_name(hmac->output_length());	454✔
456	hmac->update(TLS_SESSION_CRYPT_KEY_NAME);	450✔
457	hmac->final(cmp_key_name.data());	450✔
458
459	if(CT::is_equal(cmp_key_name.data(), key_name, TLS_SESSION_CRYPT_KEY_NAME_LEN).as_bool() == false) {	900✔
460	throw Decoding_Error("Wrong key name for encrypted session");	1✔
461	}
462
463	hmac->update(key_seed, TLS_SESSION_CRYPT_AEAD_KEY_SEED_LEN);	449✔
464	const secure_vector<uint8_t> aead_key = hmac->final();	449✔
465
466	auto aead = AEAD_Mode::create_or_throw(TLS_SESSION_CRYPT_AEAD, Cipher_Dir::Decryption);	452✔
467	aead->set_key(aead_key);	449✔
468	aead->set_associated_data(in.data(), TLS_SESSION_CRYPT_HDR_LEN);	449✔
469	aead->start(aead_nonce, TLS_SESSION_CRYPT_AEAD_NONCE_LEN);	449✔
470	aead->finish(ctext, 0);	449✔
471	return Session(ctext);	449✔
472	} catch(std::exception& e) {	2,251✔
473	throw Decoding_Error("Failed to decrypt serialized TLS session: " + std::string(e.what()));	14✔
474	}	7✔
475	}
476
477	} // namespace Botan::TLS

randombit / botan / 6546858227

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