propagate from branch 'net.randombit.botan' (head 058444ec216dd9690938c82922d911df2da535b4)

            to branch 'net.randombit.botan.tls-state-machine' (head 54985e112aecb7b7c98a7dace924a2f704e6c9c1)

1 files changed, 391 insertions, 0 deletions

diff --git a/src/tls/c_kex.cpp b/src/tls/c_kex.cpp
new file mode 100644
index 000000000..16c02e2b8
--- /dev/null
+++ b/src/tls/c_kex.cpp
@@ -0,0 +1,391 @@
+/*
+* 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/tls_record.h>
+#include <botan/internal/assert.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 {
+
+SecureVector<byte> strip_leading_zeros(const MemoryRegion<byte>& input)
+   {
+   size_t leading_zeros = 0;
+
+   for(size_t i = 0; i != input.size(); ++i)
+      {
+      if(input[i] != 0)
+         break;
+      ++leading_zeros;
+      }
+
+   SecureVector<byte> output(&input[leading_zeros],
+                             input.size() - leading_zeros);
+   return output;
+   }
+
+}
+
+/*
+* Create a new Client Key Exchange message
+*/
+Client_Key_Exchange::Client_Key_Exchange(Record_Writer& writer,
+                                         Handshake_State* state,
+                                         Credentials_Manager& creds,
+                                         const std::vector<X509_Certificate>& peer_certs,
+                                         const std::string& hostname,
+                                         RandomNumberGenerator& rng)
+   {
+   const std::string kex_algo = state->suite.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(key_material, psk_identity, 2);
+
+      SymmetricKey psk = creds.psk("tls-client", hostname, psk_identity);
+
+      MemoryVector<byte> zeros(psk.length());
+
+      append_tls_length_value(pre_master, zeros, 2);
+      append_tls_length_value(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(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");
+
+         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);
+
+         // FIXME Check that public key is residue?
+
+         DH_PrivateKey priv_key(rng, group);
+
+         PK_Key_Agreement ka(priv_key, "Raw");
+
+         SecureVector<byte> dh_secret = strip_leading_zeros(
+            ka.derive_key(0, counterparty_key.public_value()).bits_of());
+
+         if(kex_algo == "DH")
+            pre_master = dh_secret;
+         else
+            {
+            append_tls_length_value(pre_master, dh_secret, 2);
+            append_tls_length_value(pre_master, psk.bits_of(), 2);
+            }
+
+         append_tls_length_value(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 " + to_string(curve_id));
+
+         EC_Group group(name);
+
+         MemoryVector<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");
+
+         SecureVector<byte> ecdh_secret = ka.derive_key(0, counterparty_key.public_value()).bits_of();
+
+         if(kex_algo == "ECDH")
+            pre_master = ecdh_secret;
+         else
+            {
+            append_tls_length_value(pre_master, ecdh_secret, 2);
+            append_tls_length_value(pre_master, psk.bits_of(), 2);
+            }
+
+         append_tls_length_value(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));
+         MemoryVector<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(key_material, BigInt::encode(srp_vals.first), 2);
+         pre_master = srp_vals.second.bits_of();
+         }
+      else
+         {
+         throw Internal_Error("Client_Key_Exchange: Unknown kex " +
+                              kex_algo);
+         }
+      }
+   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(peer_certs.empty())
+         throw Internal_Error("No certificate and no server key exchange");
+
+      std::auto_ptr<Public_Key> pub_key(peer_certs[0].subject_public_key());
+
+      if(const RSA_PublicKey* rsa_pub = dynamic_cast<const RSA_PublicKey*>(pub_key.get()))
+         {
+         const Protocol_Version pref_version = state->client_hello->version();
+
+         pre_master = rng.random_vec(48);
+         pre_master[0] = pref_version.major_version();
+         pre_master[1] = pref_version.minor_version();
+
+         PK_Encryptor_EME encryptor(*rsa_pub, "PKCS1v15");
+
+         MemoryVector<byte> encrypted_key = encryptor.encrypt(pre_master, rng);
+
+         if(state->version() == Protocol_Version::SSL_V3)
+            key_material = encrypted_key; // no length field
+         else
+            append_tls_length_value(key_material, encrypted_key, 2);
+         }
+      else
+         throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
+                             "Expected a RSA key in server cert but got " +
+                             pub_key->algo_name());
+      }
+
+   state->hash.update(writer.send(*this));
+   }
+
+/*
+* Read a Client Key Exchange message
+*/
+Client_Key_Exchange::Client_Key_Exchange(const MemoryRegion<byte>& contents,
+                                         const Handshake_State* state,
+                                         Credentials_Manager& creds,
+                                         const Policy& policy,
+                                         RandomNumberGenerator& rng)
+   {
+   const std::string kex_algo = state->suite.kex_algo();
+
+   if(kex_algo == "RSA")
+      {
+      BOTAN_ASSERT(state->server_certs && !state->server_certs->cert_chain().empty(),
+                   "No server certificate to use for RSA");
+
+      const Private_Key* private_key = state->server_rsa_kex_key;
+
+      if(!private_key)
+         throw Internal_Error("Expected RSA kex but no server kex key set");
+
+      if(!dynamic_cast<const RSA_PrivateKey*>(private_key))
+         throw Internal_Error("Expected RSA key but got " + private_key->algo_name());
+
+      PK_Decryptor_EME decryptor(*private_key, "PKCS1v15");
+
+      Protocol_Version client_version = state->client_hello->version();
+
+      try
+         {
+         if(state->version() == Protocol_Version::SSL_V3)
+            {
+            pre_master = decryptor.decrypt(contents);
+            }
+         else
+            {
+            TLS_Data_Reader reader(contents);
+            pre_master = decryptor.decrypt(reader.get_range<byte>(2, 0, 65535));
+            }
+
+         if(pre_master.size() != 48 ||
+            client_version.major_version() != pre_master[0] ||
+            client_version.minor_version() != pre_master[1])
+            {
+            throw Decoding_Error("Client_Key_Exchange: Secret corrupted");
+            }
+         }
+      catch(...)
+         {
+         // Randomize the hide timing channel
+         pre_master = rng.random_vec(48);
+         pre_master[0] = client_version.major_version();
+         pre_master[1] = client_version.minor_version();
+         }
+      }
+   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")
+         {
+         MemoryVector<byte> zeros(psk.length());
+         append_tls_length_value(pre_master, zeros, 2);
+         append_tls_length_value(pre_master, psk.bits_of(), 2);
+         }
+      else if(kex_algo == "SRP_SHA")
+         {
+         throw Internal_Error("SRP_SHA server side not done");
+         }
+      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");
+
+            MemoryVector<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);
+
+            SecureVector<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(pre_master, shared_secret, 2);
+               append_tls_length_value(pre_master, psk.bits_of(), 2);
+               }
+            else
+               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.
+            */
+            pre_master = rng.random_vec(ka_key->public_value().size());
+            }
+         }
+      else
+         throw Internal_Error("Client_Key_Exchange: Unknown kex type " + kex_algo);
+      }
+   }
+
+}
+
+}