Updating D2D protocol to v1 to support separate sequence numbers.

components/cryptauth/session_keys.h

Index: components/cryptauth/session_keys.h
diff --git a/components/cryptauth/session_keys.h b/components/cryptauth/session_keys.h
new file mode 100644
index 0000000000000000000000000000000000000000..c9d0e394de76a2e7145ac8c53f3ba64dc0412021
--- /dev/null
+++ b/components/cryptauth/session_keys.h
@@ -0,0 +1,41 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_CRYPTAUTH_SESSION_KEYS_H_
+#define COMPONENTS_CRYPTAUTH_SESSION_KEYS_H_
+
+#include <string>
+
+#include "base/macros.h"
+
+namespace cryptauth {
+
+// This class contains the secure channel (secure context) session keys. This
+// class derives (from the master symmetric key) different keys for encryption
+// and decryption. The protocol initiator (i.e. the Chromebook) should use
+// |initiator_encode_key()| to encrypt the messages, and the responder should
+// use |responder_encode_key()|. This is reversed for decryption.
+class SessionKeys {
+ public:
+  // Create session keys derived from the |master_symmetric_key|.
+  explicit SessionKeys(const std::string& master_symmetric_key);
+
+  SessionKeys();
+
+  virtual ~SessionKeys();
+
+  virtual std::string initiator_encode_key() const;
+  virtual std::string responder_encode_key() const;
+
+ private:
+  // The initiator encoding key.
+  std::string initiator_encode_key_;
+
+  // The responder encoding key.
+  std::string responder_encode_key_;
+};
+
+}  // namespace cryptauth
+
+#endif  // COMPONENTS_CRYPTAUTH_SESSION_KEYS_H_