Move lib into src

1 files changed, 419 insertions, 0 deletions

diff --git a/src/lib/tls/msg_client_kex.cpp b/src/lib/tls/msg_client_kex.cpp
new file mode 100644
index 000000000..ae8b82fd4
--- /dev/null
+++ b/src/lib/tls/msg_client_kex.cpp
@@ -0,0 +1,419 @@
+/*
+* Client Key Exchange Message
+* (C) 2004-2010 Jack Lloyd
+*
+* Released under the terms of the Botan license
+*/
+
+#include <botan/internal/tls_messages.h>
+#include <botan/internal/tls_reader.h>
+#include <botan/internal/tls_extensions.h>
+#include <botan/internal/tls_handshake_io.h>
+#include <botan/credentials_manager.h>
+#include <botan/pubkey.h>
+#include <botan/dh.h>
+#include <botan/ecdh.h>
+#include <botan/rsa.h>
+#include <botan/srp6.h>
+#include <botan/rng.h>
+#include <botan/loadstor.h>
+#include <memory>
+
+namespace Botan {
+
+namespace TLS {
+
+namespace {
+
+secure_vector<byte> strip_leading_zeros(const secure_vector<byte>& input)
+   {
+   size_t leading_zeros = 0;
+
+   for(size_t i = 0; i != input.size(); ++i)
+      {
+      if(input[i] != 0)
+         break;
+      ++leading_zeros;
+      }
+
+   secure_vector<byte> output(&input[leading_zeros],
+                              &input[input.size()]);
+   return output;
+   }
+
+}
+
+/*
+* 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,
+                                         const std::string& hostname,
+                                         RandomNumberGenerator& rng)
+   {
+   const std::string kex_algo = state.ciphersuite().kex_algo();
+
+   if(kex_algo == "PSK")
+      {
+      std::string identity_hint = "";
+
+      if(state.server_kex())
+         {
+         TLS_Data_Reader reader(state.server_kex()->params());
+         identity_hint = reader.get_string(2, 0, 65535);
+         }
+
+      const std::string hostname = state.client_hello()->sni_hostname();
+
+      const std::string psk_identity = creds.psk_identity("tls-client",
+                                                          hostname,
+                                                          identity_hint);
+
+      append_tls_length_value(m_key_material, psk_identity, 2);
+
+      SymmetricKey psk = creds.psk("tls-client", hostname, psk_identity);
+
+      std::vector<byte> 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(state.server_kex()->params());
+
+      SymmetricKey psk;
+
+      if(kex_algo == "DHE_PSK" || kex_algo == "ECDHE_PSK")
+         {
+         std::string identity_hint = reader.get_string(2, 0, 65535);
+
+         const std::string hostname = state.client_hello()->sni_hostname();
+
+         const std::string psk_identity = creds.psk_identity("tls-client",
+                                                             hostname,
+                                                             identity_hint);
+
+         append_tls_length_value(m_key_material, psk_identity, 2);
+
+         psk = creds.psk("tls-client", hostname, psk_identity);
+         }
+
+      if(kex_algo == "DH" || kex_algo == "DHE_PSK")
+         {
+         BigInt p = BigInt::decode(reader.get_range<byte>(2, 1, 65535));
+         BigInt g = BigInt::decode(reader.get_range<byte>(2, 1, 65535));
+         BigInt Y = BigInt::decode(reader.get_range<byte>(2, 1, 65535));
+
+         if(reader.remaining_bytes())
+            throw Decoding_Error("Bad params size for DH key exchange");
+
+         if(p.bits() < policy.minimum_dh_group_size())
+            throw TLS_Exception(Alert::INSUFFICIENT_SECURITY,
+                                "Server sent DH group of " +
+                                std::to_string(p.bits()) +
+                                " bits, policy requires at least " +
+                                std::to_string(policy.minimum_dh_group_size()));
+
+         /*
+         * A basic check for key validity. As we do not know q here we
+         * cannot check that Y is in the right subgroup. However since
+         * our key is ephemeral there does not seem to be any
+         * advantage to bogus keys anyway.
+         */
+         if(Y <= 1 || Y >= p - 1)
+            throw TLS_Exception(Alert::INSUFFICIENT_SECURITY,
+                                "Server sent bad DH key for DHE exchange");
+
+         DL_Group group(p, g);
+
+         if(!group.verify_group(rng, true))
+            throw Internal_Error("DH group failed validation, possible attack");
+
+         DH_PublicKey counterparty_key(group, Y);
+
+         DH_PrivateKey priv_key(rng, group);
+
+         PK_Key_Agreement ka(priv_key, "Raw");
+
+         secure_vector<byte> dh_secret = strip_leading_zeros(
+            ka.derive_key(0, counterparty_key.public_value()).bits_of());
+
+         if(kex_algo == "DH")
+            m_pre_master = dh_secret;
+         else
+            {
+            append_tls_length_value(m_pre_master, dh_secret, 2);
+            append_tls_length_value(m_pre_master, psk.bits_of(), 2);
+            }
+
+         append_tls_length_value(m_key_material, priv_key.public_value(), 2);
+         }
+      else if(kex_algo == "ECDH" || kex_algo == "ECDHE_PSK")
+         {
+         const byte curve_type = reader.get_byte();
+
+         if(curve_type != 3)
+            throw Decoding_Error("Server sent non-named ECC curve");
+
+         const u16bit curve_id = reader.get_u16bit();
+
+         const std::string name = Supported_Elliptic_Curves::curve_id_to_name(curve_id);
+
+         if(name == "")
+            throw Decoding_Error("Server sent unknown named curve " + std::to_string(curve_id));
+
+         EC_Group group(name);
+
+         std::vector<byte> ecdh_key = reader.get_range<byte>(1, 1, 255);
+
+         ECDH_PublicKey counterparty_key(group, OS2ECP(ecdh_key, group.get_curve()));
+
+         ECDH_PrivateKey priv_key(rng, group);
+
+         PK_Key_Agreement ka(priv_key, "Raw");
+
+         secure_vector<byte> ecdh_secret =
+            ka.derive_key(0, counterparty_key.public_value()).bits_of();
+
+         if(kex_algo == "ECDH")
+            m_pre_master = ecdh_secret;
+         else
+            {
+            append_tls_length_value(m_pre_master, ecdh_secret, 2);
+            append_tls_length_value(m_pre_master, psk.bits_of(), 2);
+            }
+
+         append_tls_length_value(m_key_material, priv_key.public_value(), 1);
+         }
+      else if(kex_algo == "SRP_SHA")
+         {
+         const BigInt N = BigInt::decode(reader.get_range<byte>(2, 1, 65535));
+         const BigInt g = BigInt::decode(reader.get_range<byte>(2, 1, 65535));
+         std::vector<byte> salt = reader.get_range<byte>(1, 1, 255);
+         const BigInt B = BigInt::decode(reader.get_range<byte>(2, 1, 65535));
+
+         const std::string srp_group = srp6_group_identifier(N, g);
+
+         const std::string srp_identifier =
+            creds.srp_identifier("tls-client", hostname);
+
+         const std::string srp_password =
+            creds.srp_password("tls-client", hostname, srp_identifier);
+
+         std::pair<BigInt, SymmetricKey> srp_vals =
+            srp6_client_agree(srp_identifier,
+                              srp_password,
+                              srp_group,
+                              "SHA-1",
+                              salt,
+                              B,
+                              rng);
+
+         append_tls_length_value(m_key_material, BigInt::encode(srp_vals.first), 2);
+         m_pre_master = srp_vals.second.bits_of();
+         }
+      else
+         {
+         throw Internal_Error("Client_Key_Exchange: Unknown kex " +
+                              kex_algo);
+         }
+
+      reader.assert_done();
+      }
+   else
+      {
+      // No server key exchange msg better mean RSA kex + RSA key in cert
+
+      if(kex_algo != "RSA")
+         throw Unexpected_Message("No server kex but negotiated kex " + kex_algo);
+
+      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()->version();
+
+         m_pre_master = rng.random_vec(48);
+         m_pre_master[0] = offered_version.major_version();
+         m_pre_master[1] = offered_version.minor_version();
+
+         PK_Encryptor_EME encryptor(*rsa_pub, "PKCS1v15");
+
+         std::vector<byte> encrypted_key = encryptor.encrypt(m_pre_master, rng);
+
+         if(state.version() == Protocol_Version::SSL_V3)
+            m_key_material = encrypted_key; // no length field
+         else
+            append_tls_length_value(m_key_material, encrypted_key, 2);
+         }
+      else
+         throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
+                             "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<byte>& contents,
+                                         const Handshake_State& state,
+                                         const Private_Key* server_rsa_kex_key,
+                                         Credentials_Manager& creds,
+                                         const Policy& policy,
+                                         RandomNumberGenerator& rng)
+   {
+   const std::string kex_algo = state.ciphersuite().kex_algo();
+
+   if(kex_algo == "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(!dynamic_cast<const RSA_PrivateKey*>(server_rsa_kex_key))
+         throw Internal_Error("Expected RSA key but got " + server_rsa_kex_key->algo_name());
+
+      PK_Decryptor_EME decryptor(*server_rsa_kex_key, "PKCS1v15");
+
+      Protocol_Version client_version = state.client_hello()->version();
+
+      /*
+      * This is used as the pre-master if RSA decryption fails.
+      * Otherwise we can be used as an oracle. See Bleichenbacher
+      * "Chosen Ciphertext Attacks against Protocols Based on RSA
+      * Encryption Standard PKCS #1", Crypto 98
+      *
+      * Create it here instead if in the catch clause as otherwise we
+      * expose a timing channel WRT the generation of the fake value.
+      * Some timing channel likely remains due to exception handling
+      * and the like.
+      */
+      secure_vector<byte> fake_pre_master = rng.random_vec(48);
+      fake_pre_master[0] = client_version.major_version();
+      fake_pre_master[1] = client_version.minor_version();
+
+      try
+         {
+         if(state.version() == Protocol_Version::SSL_V3)
+            {
+            m_pre_master = decryptor.decrypt(contents);
+            }
+         else
+            {
+            TLS_Data_Reader reader(contents);
+            m_pre_master = decryptor.decrypt(reader.get_range<byte>(2, 0, 65535));
+            }
+
+         if(m_pre_master.size() != 48 ||
+            client_version.major_version() != m_pre_master[0] ||
+            client_version.minor_version() != m_pre_master[1])
+            {
+            throw Decoding_Error("Client_Key_Exchange: Secret corrupted");
+            }
+         }
+      catch(...)
+         {
+         m_pre_master = fake_pre_master;
+         }
+      }
+   else
+      {
+      TLS_Data_Reader reader(contents);
+
+      SymmetricKey psk;
+
+      if(kex_algo == "PSK" || kex_algo == "DHE_PSK" || kex_algo == "ECDHE_PSK")
+         {
+         const std::string psk_identity = reader.get_string(2, 0, 65535);
+
+         psk = creds.psk("tls-server",
+                         state.client_hello()->sni_hostname(),
+                         psk_identity);
+
+         if(psk.length() == 0)
+            {
+            if(policy.hide_unknown_users())
+               psk = SymmetricKey(rng, 16);
+            else
+               throw TLS_Exception(Alert::UNKNOWN_PSK_IDENTITY,
+                                   "No PSK for identifier " + psk_identity);
+            }
+         }
+
+      if(kex_algo == "PSK")
+         {
+         std::vector<byte> 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 == "SRP_SHA")
+         {
+         SRP6_Server_Session& srp = state.server_kex()->server_srp_params();
+
+         m_pre_master = srp.step2(BigInt::decode(reader.get_range<byte>(2, 0, 65535))).bits_of();
+         }
+      else if(kex_algo == "DH" || kex_algo == "DHE_PSK" ||
+              kex_algo == "ECDH" || kex_algo == "ECDHE_PSK")
+         {
+         const Private_Key& private_key = state.server_kex()->server_kex_key();
+
+         const PK_Key_Agreement_Key* ka_key =
+            dynamic_cast<const PK_Key_Agreement_Key*>(&private_key);
+
+         if(!ka_key)
+            throw Internal_Error("Expected key agreement key type but got " +
+                                 private_key.algo_name());
+
+         try
+            {
+            PK_Key_Agreement ka(*ka_key, "Raw");
+
+            std::vector<byte> client_pubkey;
+
+            if(ka_key->algo_name() == "DH")
+               client_pubkey = reader.get_range<byte>(2, 0, 65535);
+            else
+               client_pubkey = reader.get_range<byte>(1, 0, 255);
+
+            secure_vector<byte> shared_secret = ka.derive_key(0, client_pubkey).bits_of();
+
+            if(ka_key->algo_name() == "DH")
+               shared_secret = strip_leading_zeros(shared_secret);
+
+            if(kex_algo == "DHE_PSK" || 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(std::exception &e)
+            {
+            /*
+            * Something failed in the DH computation. To avoid possible
+            * timing attacks, randomize the pre-master output and carry
+            * on, allowing the protocol to fail later in the finished
+            * checks.
+            */
+            m_pre_master = rng.random_vec(ka_key->public_value().size());
+            }
+         }
+      else
+         throw Internal_Error("Client_Key_Exchange: Unknown kex type " + kex_algo);
+      }
+   }
+
+}
+
+}