diff --git a/lib/keychain.h b/lib/keychain.h
new file mode 100644
index 0000000..0cfa3d5
--- /dev/null
+++ b/lib/keychain.h
@@ -0,0 +1,56 @@
+/* key-chain for authentication.
+ * Copyright (C) 2000 Kunihiro Ishiguro
+ *
+ * This file is part of GNU Zebra.
+ *
+ * GNU Zebra is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; either version 2, or (at your
+ * option) any later version.
+ *
+ * GNU Zebra is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Zebra; see the file COPYING.  If not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifndef _ZEBRA_KEYCHAIN_H
+#define _ZEBRA_KEYCHAIN_H
+
+struct keychain
+{
+  char *name;
+
+  struct list *key;
+};
+
+struct key_range
+{
+  time_t start;
+  time_t end;
+
+  u_char duration;
+};
+
+struct key
+{
+  u_int32_t index;
+
+  char *string;
+
+  struct key_range send;
+  struct key_range accept;
+};
+
+void keychain_init ();
+struct keychain *keychain_lookup (char *);
+struct key *key_lookup_for_accept (struct keychain *, u_int32_t);
+struct key *key_match_for_accept (struct keychain *, char *);
+struct key *key_lookup_for_send (struct keychain *);
+
+#endif /* _ZEBRA_KEYCHAIN_H */