5587580523

Committed 18 Jul 2023 12:45PM UTC coverage: 91.72% (+0.03%) from 91.691%

Build # 5587580523

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Pull #3618

github

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web-flow

Commit Message

Merge b6d23d19e into 65b754862

Pull Request Pull Request #3618: [TLS 1.3] PSK Support

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99.16

/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/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(is_dh(group)) {
               return Kex_Algo::DHE_PSK;
            } else if(is_ecdh(group) || is_x25519(group)) {
               return Kex_Algo::ECDHE_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(is_dh(group)) {
            return Kex_Algo::DH;
         } else if(is_ecdh(group) || is_x25519(group)) {
            return Kex_Algo::ECDH;
         }
      }

      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");
      }

      // TODO: replace those raw pointers with sub-spans into `in`
      const uint8_t* magic = in.data();
      const uint8_t* key_name = magic + TLS_SESSION_CRYPT_MAGIC_LEN;
      const uint8_t* key_seed = key_name + TLS_SESSION_CRYPT_KEY_NAME_LEN;
      const uint8_t* aead_nonce = key_seed + TLS_SESSION_CRYPT_AEAD_KEY_SEED_LEN;
      const uint8_t* ctext = aead_nonce + TLS_SESSION_CRYPT_AEAD_NONCE_LEN;
      const size_t ctext_len = in.size() - TLS_SESSION_CRYPT_HDR_LEN;  // includes the tag

      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(same_mem(cmp_key_name.data(), key_name, TLS_SESSION_CRYPT_KEY_NAME_LEN) == 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);
      secure_vector<uint8_t> buf(ctext, ctext + ctext_len);
      aead->finish(buf, 0);
      return Session(buf);
   } 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/loadstor.h>
18
19	#include <botan/tls_callbacks.h>
20	#include <botan/tls_messages.h>
21
22	#include <botan/internal/stl_util.h>
23
24	#include <utility>
25
26	namespace Botan::TLS {
27
28	void Session_Handle::validate_constraints() const {	3,466✔
29	std::visit(overloaded{	6,932✔
30	[](const Session_ID& id) {	657✔
31	// RFC 5246 7.4.1.2
32	// opaque SessionID<0..32>;
33	BOTAN_ARG_CHECK(!id.empty(), "Session ID must not be empty");	657✔
34	BOTAN_ARG_CHECK(id.size() <= 32, "Session ID cannot be longer than 32 bytes");	657✔
35	},	657✔
36	[](const Session_Ticket& ticket) {	2,129✔
37	BOTAN_ARG_CHECK(!ticket.empty(), "Ticket most not be empty");	2,129✔
38	BOTAN_ARG_CHECK(ticket.size() <= std::numeric_limits<uint16_t>::max(),	2,129✔
39	"Ticket cannot be longer than 64kB");
40	},	2,129✔
41	[](const Opaque_Session_Handle& handle) {	680✔
42	// RFC 8446 4.6.1
43	// opaque ticket<1..2^16-1>;
44	BOTAN_ARG_CHECK(!handle.empty(), "Opaque session handle must not be empty");	680✔
45	BOTAN_ARG_CHECK(handle.size() <= std::numeric_limits<uint16_t>::max(),	680✔
46	"Opaque session handle cannot be longer than 64kB");
47	},	680✔
48	},
49	m_handle);	3,466✔
50	}	3,466✔
51
52	Opaque_Session_Handle Session_Handle::opaque_handle() const {	362✔
53	// both a Session_ID and a Session_Ticket could be an Opaque_Session_Handle
54	return Opaque_Session_Handle(std::visit([](const auto& handle) { return handle.get(); }, m_handle));	724✔
55	}
56
57	std::optional<Session_ID> Session_Handle::id() const {	2,422✔
58	if(is_id()) {	2,422✔
59	return std::get<Session_ID>(m_handle);	617✔
60	}
61
62	// Opaque handles can mimick as a Session_ID if they are short enough
63	if(is_opaque_handle()) {	1,805✔
64	const auto& handle = std::get<Opaque_Session_Handle>(m_handle);	672✔
65	if(handle.size() <= 32) {	672✔
66	return Session_ID(handle.get());	24✔
67	}
68	}
69
70	return std::nullopt;	1,781✔
71	}
72
73	std::optional<Session_Ticket> Session_Handle::ticket() const {	1,714✔
74	if(is_ticket()) {	1,714✔
75	return std::get<Session_Ticket>(m_handle);	1,205✔
76	}
77
78	// Opaque handles can mimick 'normal' Session_Tickets at any time
79	if(is_opaque_handle()) {	509✔
80	return Session_Ticket(std::get<Opaque_Session_Handle>(m_handle).get());	216✔
81	}
82
83	return std::nullopt;	293✔
84	}
85
86	Ciphersuite Session_Base::ciphersuite() const {	4,816✔
87	auto suite = Ciphersuite::by_id(m_ciphersuite);	4,816✔
88	if(!suite.has_value()) {	4,816✔
89	throw Decoding_Error("Failed to find cipher suite for ID " + std::to_string(m_ciphersuite));	×
90	}
91	return suite.value();	4,816✔
92	}
93
94	Session_Summary::Session_Summary(const Session_Base& base,	1,741✔
95	bool was_resumption,
96	std::optional<std::string> psk_identity) :	1,741✔
97	Session_Base(base), m_external_psk_identity(std::move(psk_identity)), m_was_resumption(was_resumption) {	1,847✔
98	BOTAN_ARG_CHECK(version().is_pre_tls_13(), "Instantiated a TLS 1.2 session summary with an newer TLS version");	1,741✔
99
100	const auto cs = ciphersuite();	1,741✔
101	m_kex_algo = cs.kex_algo();	1,741✔
102	}	1,741✔
103
104	#if defined(BOTAN_HAS_TLS_13)
105
106	Session_Summary::Session_Summary(const Server_Hello_13& server_hello,	589✔
107	Connection_Side side,
108	std::vector<X509_Certificate> peer_certs,
109	std::optional<std::string> psk_identity,
110	bool session_was_resumed,
111	Server_Information server_info,
112	std::chrono::system_clock::time_point current_timestamp) :	589✔
113	Session_Base(current_timestamp,
114	server_hello.selected_version(),
115	server_hello.ciphersuite(),	589✔
116	side,
117
118	// TODO: SRTP might become necessary when DTLS 1.3 is being implemented
119	0,
120
121	// RFC 8446 Appendix D
122	// Because TLS 1.3 always hashes in the transcript up to the server
123	// Finished, implementations which support both TLS 1.3 and earlier
124	// versions SHOULD indicate the use of the Extended Master Secret
125	// extension in their APIs whenever TLS 1.3 is used.
126	true,
127
128	// TLS 1.3 uses AEADs, so technically encrypt-then-MAC is not applicable.
129	false,
130	std::move(peer_certs),	589✔
131	std::move(server_info)),	589✔
132	m_external_psk_identity(std::move(psk_identity)),	589✔
133	m_was_resumption(session_was_resumed) {	1,180✔
134	BOTAN_ARG_CHECK(version().is_tls_13_or_later(), "Instantiated a TLS 1.3 session summary with an older TLS version");	589✔
135	set_session_id(server_hello.session_id());	1,178✔
136
137	// In TLS 1.3 the key exchange algorithm is not negotiated in the ciphersuite
138	// anymore. This provides a compatible identifier for applications to use.
139	m_kex_algo = kex_method_to_string([&] {	589✔
140	if(psk_used() \|\| was_resumption()) {	589✔
141	if(const auto keyshare = server_hello.extensions().get<Key_Share>()) {	163✔
142	const auto group = keyshare->selected_group();	163✔
143	if(is_dh(group)) {	163✔
144	return Kex_Algo::DHE_PSK;
145	} else if(is_ecdh(group) \|\| is_x25519(group)) {	163✔
146	return Kex_Algo::ECDHE_PSK;	163✔
147	}
148	} else {
149	return Kex_Algo::PSK;
150	}
151	} else {
152	const auto keyshare = server_hello.extensions().get<Key_Share>();	426✔
153	BOTAN_ASSERT_NONNULL(keyshare);	426✔
154	const auto group = keyshare->selected_group();	426✔
155	if(is_dh(group)) {	426✔
156	return Kex_Algo::DH;
157	} else if(is_ecdh(group) \|\| is_x25519(group)) {	426✔
158	return Kex_Algo::ECDH;	426✔
159	}
160	}
161
162	return Kex_Algo::UNDEFINED;
163	}());	589✔
164	}	589✔
165
166	#endif
167
168	Session::Session(const secure_vector<uint8_t>& master_secret,	1,616✔
169	Protocol_Version version,
170	uint16_t ciphersuite,
171	Connection_Side side,
172	bool extended_master_secret,
173	bool encrypt_then_mac,
174	const std::vector<X509_Certificate>& certs,
175	const Server_Information& server_info,
176	uint16_t srtp_profile,
177	std::chrono::system_clock::time_point current_timestamp,
178	std::chrono::seconds lifetime_hint) :	1,616✔
179	Session_Base(current_timestamp,
180	version,
181	ciphersuite,
182	side,
183	srtp_profile,
184	extended_master_secret,
185	encrypt_then_mac,
186	certs,
187	server_info),
188	m_master_secret(master_secret),	1,616✔
189	m_early_data_allowed(false),	1,616✔
190	m_max_early_data_bytes(0),	1,616✔
191	m_ticket_age_add(0),	1,616✔
192	m_lifetime_hint(lifetime_hint) {	1,616✔
193	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✔
194	}	1,616✔
195
196	#if defined(BOTAN_HAS_TLS_13)
197
198	Session::Session(const secure_vector<uint8_t>& session_psk,	567✔
199	const std::optional<uint32_t>& max_early_data_bytes,
200	uint32_t ticket_age_add,
201	std::chrono::seconds lifetime_hint,
202	Protocol_Version version,
203	uint16_t ciphersuite,
204	Connection_Side side,
205	const std::vector<X509_Certificate>& peer_certs,
206	const Server_Information& server_info,
207	std::chrono::system_clock::time_point current_timestamp) :	567✔
208	Session_Base(current_timestamp,
209	version,
210	ciphersuite,
211	side,
212
213	// TODO: SRTP might become necessary when DTLS 1.3 is being implemented
214	0,
215
216	// RFC 8446 Appendix D
217	// Because TLS 1.3 always hashes in the transcript up to the server
218	// Finished, implementations which support both TLS 1.3 and earlier
219	// versions SHOULD indicate the use of the Extended Master Secret
220	// extension in their APIs whenever TLS 1.3 is used.
221	true,
222
223	// TLS 1.3 uses AEADs, so technically encrypt-then-MAC is not applicable.
224	false,
225	peer_certs,
226	server_info),
227	m_master_secret(session_psk),	567✔
228	m_early_data_allowed(max_early_data_bytes.has_value()),	567✔
229	m_max_early_data_bytes(max_early_data_bytes.value_or(0)),	567✔
230	m_ticket_age_add(ticket_age_add),	567✔
231	m_lifetime_hint(lifetime_hint) {	567✔
232	BOTAN_ARG_CHECK(!version.is_pre_tls_13(), "Instantiated a TLS 1.3 session object with a TLS version older than 1.3");	567✔
233	}	567✔
234
235	Session::Session(secure_vector<uint8_t>&& session_psk,	276✔
236	const std::optional<uint32_t>& max_early_data_bytes,
237	std::chrono::seconds lifetime_hint,
238	const std::vector<X509_Certificate>& peer_certs,
239	const Client_Hello_13& client_hello,
240	const Server_Hello_13& server_hello,
241	Callbacks& callbacks,
242	RandomNumberGenerator& rng) :	276✔
243	Session_Base(callbacks.tls_current_timestamp(),	276✔
244	server_hello.selected_version(),
245	server_hello.ciphersuite(),	276✔
246	Connection_Side::Server,
247	0,
248	true,
249	false, // see constructor above for rationales
250	peer_certs,
251	Server_Information(client_hello.sni_hostname())),	552✔
252	m_master_secret(std::move(session_psk)),	276✔
253	m_early_data_allowed(max_early_data_bytes.has_value()),	276✔
254	m_max_early_data_bytes(max_early_data_bytes.value_or(0)),	276✔
255	m_ticket_age_add(load_be<uint32_t>(rng.random_vec(4).data(), 0)),	276✔
256	m_lifetime_hint(lifetime_hint) {	828✔
257	BOTAN_ARG_CHECK(!m_version.is_pre_tls_13(),	276✔
258	"Instantiated a TLS 1.3 session object with a TLS version older than 1.3");
259	}	276✔
260
261	#endif
262
263	Session::Session(std::string_view pem) : Session(PEM_Code::decode_check_label(pem, "TLS SESSION")) {}	3✔
264
265	Session::Session(std::span<const uint8_t> ber_data) {	455✔
266	uint8_t side_code = 0;	455✔
267
268	ASN1_String server_hostname;	455✔
269	ASN1_String server_service;	455✔
270	size_t server_port;	455✔
271
272	uint8_t major_version = 0, minor_version = 0;	455✔
273
274	size_t start_time = 0;	455✔
275	size_t srtp_profile = 0;	455✔
276	uint16_t ciphersuite_code = 0;	455✔
277	uint64_t lifetime_hint = 0;	455✔
278
279	BER_Decoder(ber_data.data(), ber_data.size())	455✔
280	.start_sequence()	910✔
281	.decode_and_check(static_cast<size_t>(TLS_SESSION_PARAM_STRUCT_VERSION),	910✔
282	"Unknown version in serialized TLS session")
283	.decode_integer_type(start_time)	455✔
284	.decode_integer_type(major_version)	455✔
285	.decode_integer_type(minor_version)	455✔
286	.decode_integer_type(ciphersuite_code)	455✔
287	.decode_integer_type(side_code)	455✔
288	.decode(m_extended_master_secret)	455✔
289	.decode(m_encrypt_then_mac)	455✔
290	.decode(m_master_secret, ASN1_Type::OctetString)	455✔
291	.decode_list<X509_Certificate>(m_peer_certs)	455✔
292	.decode(server_hostname)	455✔
293	.decode(server_service)	455✔
294	.decode(server_port)	455✔
295	.decode(srtp_profile)	455✔
296	.decode(m_early_data_allowed)	455✔
297	.decode_integer_type(m_max_early_data_bytes)	455✔
298	.decode_integer_type(m_ticket_age_add)	455✔
299	.decode_integer_type(lifetime_hint)	455✔
300	.end_cons()	455✔
301	.verify_end();	455✔
302
303	if(!Ciphersuite::by_id(ciphersuite_code)) {	455✔
304	throw Decoding_Error(	1✔
305	"Serialized TLS session contains unknown cipher suite "
306	"(" +	2✔
307	std::to_string(ciphersuite_code) + ")");	4✔
308	}
309
310	m_ciphersuite = ciphersuite_code;	454✔
311	m_version = Protocol_Version(major_version, minor_version);	454✔
312	m_start_time = std::chrono::system_clock::from_time_t(start_time);	454✔
313	m_connection_side = static_cast<Connection_Side>(side_code);	454✔
314	m_srtp_profile = static_cast<uint16_t>(srtp_profile);	454✔
315
316	m_server_info =	454✔
317	Server_Information(server_hostname.value(), server_service.value(), static_cast<uint16_t>(server_port));	908✔
318
319	m_lifetime_hint = std::chrono::seconds(lifetime_hint);	454✔
320	}	458✔
321
322	secure_vector<uint8_t> Session::DER_encode() const {	1,124✔
323	return DER_Encoder()	1,124✔
324	.start_sequence()	1,124✔
325	.encode(static_cast<size_t>(TLS_SESSION_PARAM_STRUCT_VERSION))	1,124✔
326	.encode(static_cast<size_t>(std::chrono::system_clock::to_time_t(m_start_time)))	1,124✔
327	.encode(static_cast<size_t>(m_version.major_version()))	1,124✔
328	.encode(static_cast<size_t>(m_version.minor_version()))	1,124✔
329	.encode(static_cast<size_t>(m_ciphersuite))	1,124✔
330	.encode(static_cast<size_t>(m_connection_side))	1,124✔
331	.encode(m_extended_master_secret)	1,124✔
332	.encode(m_encrypt_then_mac)	1,124✔
333	.encode(m_master_secret, ASN1_Type::OctetString)	1,124✔
334	.start_sequence()	1,492✔
335	.encode_list(m_peer_certs)	1,124✔
336	.end_cons()	1,124✔
337	.encode(ASN1_String(m_server_info.hostname(), ASN1_Type::Utf8String))	3,618✔
338	.encode(ASN1_String(m_server_info.service(), ASN1_Type::Utf8String))	3,372✔
339	.encode(static_cast<size_t>(m_server_info.port()))	1,124✔
340	.encode(static_cast<size_t>(m_srtp_profile))	1,124✔
341
342	// the fields below were introduced for TLS 1.3 session tickets
343	.encode(m_early_data_allowed)	1,124✔
344	.encode(static_cast<size_t>(m_max_early_data_bytes))	1,124✔
345	.encode(static_cast<size_t>(m_ticket_age_add))	1,124✔
346	.encode(static_cast<size_t>(m_lifetime_hint.count()))	1,124✔
347	.end_cons()	1,124✔
348	.get_contents();	2,248✔
349	}
350
351	std::string Session::PEM_encode() const {	2✔
352	return PEM_Code::encode(this->DER_encode(), "TLS SESSION");	6✔
353	}
354
355	secure_vector<uint8_t> Session::extract_master_secret() {	177✔
356	BOTAN_STATE_CHECK(!m_master_secret.empty());	177✔
357	return std::exchange(m_master_secret, {});	177✔
358	}
359
360	namespace {
361
362	// The output length of the HMAC must be a valid keylength for the AEAD
363	const char* const TLS_SESSION_CRYPT_HMAC = "HMAC(SHA-512-256)";
364	// SIV would be better, but we can't assume it is available
365	const char* const TLS_SESSION_CRYPT_AEAD = "AES-256/GCM";
366	const char* const TLS_SESSION_CRYPT_KEY_NAME = "BOTAN TLS SESSION KEY NAME";
367	const uint64_t TLS_SESSION_CRYPT_MAGIC = 0x068B5A9D396C0000;
368	const size_t TLS_SESSION_CRYPT_MAGIC_LEN = 8;
369	const size_t TLS_SESSION_CRYPT_KEY_NAME_LEN = 4;
370	const size_t TLS_SESSION_CRYPT_AEAD_NONCE_LEN = 12;
371	const size_t TLS_SESSION_CRYPT_AEAD_KEY_SEED_LEN = 16;
372	const size_t TLS_SESSION_CRYPT_AEAD_TAG_SIZE = 16;
373
374	const size_t TLS_SESSION_CRYPT_HDR_LEN = TLS_SESSION_CRYPT_MAGIC_LEN + TLS_SESSION_CRYPT_KEY_NAME_LEN +
375	TLS_SESSION_CRYPT_AEAD_NONCE_LEN + TLS_SESSION_CRYPT_AEAD_KEY_SEED_LEN;
376
377	const size_t TLS_SESSION_CRYPT_OVERHEAD = TLS_SESSION_CRYPT_HDR_LEN + TLS_SESSION_CRYPT_AEAD_TAG_SIZE;
378
379	} // namespace
380
381	std::vector<uint8_t> Session::encrypt(const SymmetricKey& key, RandomNumberGenerator& rng) const {	1,116✔
382	auto hmac = MessageAuthenticationCode::create_or_throw(TLS_SESSION_CRYPT_HMAC);	1,116✔
383	hmac->set_key(key);	1,116✔
384
385	// First derive the "key name"
386	std::vector<uint8_t> key_name(hmac->output_length());	1,116✔
387	hmac->update(TLS_SESSION_CRYPT_KEY_NAME);	1,116✔
388	hmac->final(key_name.data());	1,116✔
389	key_name.resize(TLS_SESSION_CRYPT_KEY_NAME_LEN);	1,116✔
390
391	std::vector<uint8_t> aead_nonce;	1,116✔
392	std::vector<uint8_t> key_seed;	1,116✔
393
394	rng.random_vec(aead_nonce, TLS_SESSION_CRYPT_AEAD_NONCE_LEN);	1,116✔
395	rng.random_vec(key_seed, TLS_SESSION_CRYPT_AEAD_KEY_SEED_LEN);	1,116✔
396
397	hmac->update(key_seed);	1,116✔
398	const secure_vector<uint8_t> aead_key = hmac->final();	1,116✔
399
400	secure_vector<uint8_t> bits = this->DER_encode();	1,116✔
401
402	// create the header
403	std::vector<uint8_t> buf;	1,116✔
404	buf.reserve(TLS_SESSION_CRYPT_OVERHEAD + bits.size());	1,116✔
405	buf.resize(TLS_SESSION_CRYPT_MAGIC_LEN);	1,116✔
406	store_be(TLS_SESSION_CRYPT_MAGIC, &buf[0]);	1,116✔
407	buf += key_name;	1,116✔
408	buf += key_seed;	1,116✔
409	buf += aead_nonce;	1,116✔
410
411	auto aead = AEAD_Mode::create_or_throw(TLS_SESSION_CRYPT_AEAD, Cipher_Dir::Encryption);	1,116✔
412	BOTAN_ASSERT_NOMSG(aead->valid_nonce_length(TLS_SESSION_CRYPT_AEAD_NONCE_LEN));	1,116✔
413	BOTAN_ASSERT_NOMSG(aead->tag_size() == TLS_SESSION_CRYPT_AEAD_TAG_SIZE);	1,116✔
414	aead->set_key(aead_key);	1,116✔
415	aead->set_associated_data(buf);	1,116✔
416	aead->start(aead_nonce);	1,116✔
417	aead->finish(bits, 0);	1,116✔
418
419	// append the ciphertext
420	buf += bits;	1,116✔
421	return buf;	1,116✔
422	}	7,812✔
423
424	Session Session::decrypt(std::span<const uint8_t> in, const SymmetricKey& key) {	456✔
425	try {	456✔
426	const size_t min_session_size = 48 + 4; // serious under-estimate	456✔
427	if(in.size() < TLS_SESSION_CRYPT_OVERHEAD + min_session_size) {	456✔
428	throw Decoding_Error("Encrypted session too short to be valid");	3✔
429	}
430
431	// TODO: replace those raw pointers with sub-spans into `in`
432	const uint8_t* magic = in.data();	453✔
433	const uint8_t* key_name = magic + TLS_SESSION_CRYPT_MAGIC_LEN;	453✔
434	const uint8_t* key_seed = key_name + TLS_SESSION_CRYPT_KEY_NAME_LEN;	453✔
435	const uint8_t* aead_nonce = key_seed + TLS_SESSION_CRYPT_AEAD_KEY_SEED_LEN;	453✔
436	const uint8_t* ctext = aead_nonce + TLS_SESSION_CRYPT_AEAD_NONCE_LEN;	453✔
437	const size_t ctext_len = in.size() - TLS_SESSION_CRYPT_HDR_LEN; // includes the tag	453✔
438
439	if(load_be<uint64_t>(magic, 0) != TLS_SESSION_CRYPT_MAGIC) {	453✔
440	throw Decoding_Error("Missing expected magic numbers");	×
441	}
442
443	auto hmac = MessageAuthenticationCode::create_or_throw(TLS_SESSION_CRYPT_HMAC);	453✔
444	hmac->set_key(key);	453✔
445
446	// First derive and check the "key name"
447	std::vector<uint8_t> cmp_key_name(hmac->output_length());	457✔
448	hmac->update(TLS_SESSION_CRYPT_KEY_NAME);	453✔
449	hmac->final(cmp_key_name.data());	453✔
450
451	if(same_mem(cmp_key_name.data(), key_name, TLS_SESSION_CRYPT_KEY_NAME_LEN) == false) {	906✔
452	throw Decoding_Error("Wrong key name for encrypted session");	1✔
453	}
454
455	hmac->update(key_seed, TLS_SESSION_CRYPT_AEAD_KEY_SEED_LEN);	452✔
456	const secure_vector<uint8_t> aead_key = hmac->final();	452✔
457
458	auto aead = AEAD_Mode::create_or_throw(TLS_SESSION_CRYPT_AEAD, Cipher_Dir::Decryption);	455✔
459	aead->set_key(aead_key);	452✔
460	aead->set_associated_data(in.data(), TLS_SESSION_CRYPT_HDR_LEN);	452✔
461	aead->start(aead_nonce, TLS_SESSION_CRYPT_AEAD_NONCE_LEN);	452✔
462	secure_vector<uint8_t> buf(ctext, ctext + ctext_len);	455✔
463	aead->finish(buf, 0);	452✔
464	return Session(buf);	452✔
465	} catch(std::exception& e) {	2,265✔
466	throw Decoding_Error("Failed to decrypt serialized TLS session: " + std::string(e.what()));	14✔
467	}	7✔
468	}
469
470	} // namespace Botan::TLS

randombit / botan / 5587580523

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