Implement the session key exchange

6 files changed, 38 insertions, 13 deletions

diff --git a/include/axolotl/account.hh b/include/axolotl/account.hh
index 5edb799..dd9c819 100644
--- a/include/axolotl/account.hh
+++ b/include/axolotl/account.hh
@@ -2,6 +2,8 @@
 #define AXOLOTL_ACCOUNT_HH_
 
 #include "axolotl/list.hh"
+#include "axolotl/crypto.hh"
+#include "axolotl/error.hh"
 
 #include <cstdint>
 
@@ -25,16 +27,21 @@ struct Account {
     LocalKey identity_key;
     LocalKey last_resort_one_time_key;
     List<LocalKey, MAX_ONE_TIME_KEYS> one_time_keys;
+    ErrorCode last_error;
 
     /** Number of random bytes needed to create a new account */
     std::size_t new_account_random_length();
 
     /** Create a new account. Returns NOT_ENOUGH_RANDOM if the number of random
      * bytes is too small. */
-    ErrorCode new_account(
+    std::size_t new_account(
         uint8_t const * random, std::size_t random_length
     );
 
+    LocalKey const * lookup_key(
+        std::uint32_t id
+    );
+
     /** The number of bytes needed to persist this account. */
     std::size_t pickle_length();
 
diff --git a/include/axolotl/crypto.hh b/include/axolotl/crypto.hh
index 42e4b61..7564e8f 100644
--- a/include/axolotl/crypto.hh
+++ b/include/axolotl/crypto.hh
@@ -12,6 +12,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+#ifndef AXOLOTL_CRYPTO_HH_
+#define AXOLOTL_CRYPTO_HH_
+
 #include <cstdint>
 #include <cstddef>
 
@@ -141,3 +144,5 @@ void hkdf_sha256(
 );
 
 } // namespace axolotl
+
+#endif /* AXOLOTL_CRYPTO_HH_ */
diff --git a/include/axolotl/error.hh b/include/axolotl/error.hh
index 712b9eb..3bf0e63 100644
--- a/include/axolotl/error.hh
+++ b/include/axolotl/error.hh
@@ -10,6 +10,7 @@ enum struct ErrorCode {
     BAD_MESSAGE_VERSION = 3,  /*!< The message version is unsupported */
     BAD_MESSAGE_FORMAT = 4, /*!< The message couldn't be decoded */
     BAD_MESSAGE_MAC = 5, /*!< The message couldn't be decrypted */
+    BAD_MESSAGE_KEY_ID = 6, /*!< The message references an unknown key id */
 };
 
 } // namespace axolotl
diff --git a/include/axolotl/list.hh b/include/axolotl/list.hh
index ae8900c..604f00f 100644
--- a/include/axolotl/list.hh
+++ b/include/axolotl/list.hh
@@ -12,6 +12,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+#ifndef AXOLOTL_LIST_HH_
+#define AXOLOTL_LIST_HH_
+
 #include <cstddef>
 
 namespace axolotl {
@@ -112,3 +115,5 @@ private:
 };
 
 } // namespace axolotl
+
+#endif /* AXOLOTL_LIST_HH_ */
diff --git a/include/axolotl/message.hh b/include/axolotl/message.hh
index 2b9bc99..5bce277 100644
--- a/include/axolotl/message.hh
+++ b/include/axolotl/message.hh
@@ -88,6 +88,7 @@ struct PreKeyMessageReader {
     std::uint8_t const * message; std::size_t message_length;
 };
 
+
 /**
  * The length of the buffer needed to hold a message.
  */
@@ -99,6 +100,7 @@ std::size_t encode_one_time_key_message_length(
     std::size_t message_length
 );
 
+
 /**
  * Writes the message headers into the output buffer.
  * Populates the writer struct with pointers into the output buffer.
diff --git a/include/axolotl/session.hh b/include/axolotl/session.hh
index c69699d..1c3395a 100644
--- a/include/axolotl/session.hh
+++ b/include/axolotl/session.hh
@@ -5,14 +5,13 @@
 
 namespace axolotl {
 
+class Account;
+
 struct RemoteKey {
     std::uint32_t id;
     Curve25519PublicKey key;
 };
 
-struct RemoteKeys {
-};
-
 
 enum struct MessageType {
     PRE_KEY_MESSAGE = 0,
@@ -21,28 +20,34 @@ enum struct MessageType {
 
 
 struct Session {
+
+    Session();
+
+    Ratchet ratchet;
+    ErrorCode last_error;
+
     bool received_message;
+
     RemoteKey alice_identity_key;
-    RemoteKey alice_base_key;
-    RemoteKey bob_identity_key;
-    RemoteKey bob_one_time_key;
-    Ratchet ratchet;
+    Curve25519PublicKey alice_base_key;
+    std::uint32_t bob_one_time_key_id;
+
 
-    void initialise_outbound_session_random_length();
+    std::size_t new_outbound_session_random_length();
 
-    void initialise_outbound_session(
+    std::size_t new_outbound_session(
         Account const & local_account,
-        RemoteKey const & identity_key,
+        Curve25519PublicKey const & identity_key,
         RemoteKey const & one_time_key,
         std::uint8_t const * random, std::size_t random_length
     );
 
-    void initialise_inbound_session(
+    std::size_t new_inbound_session(
         Account & local_account,
         std::uint8_t const * one_time_key_message, std::size_t message_length
     );
 
-    void matches_inbound_session(
+    bool matches_inbound_session(
         std::uint8_t const * one_time_key_message, std::size_t message_length
     );