------------------------------------------------------------------------------
--                              Ada Web Server                              --
--                                                                          --
--                         Copyright (C) 2000-2007                          --
--                                 AdaCore                                  --
--                                                                          --
--  This library is free software; you can redistribute it and/or modify    --
--  it under the terms of the GNU General Public License as published by    --
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--  This library is distributed in the hope that it will be useful, but     --
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--  General Public License for more details.                                --
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--  You should have received a copy of the GNU General Public License       --
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--  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.          --
--                                                                          --
------------------------------------------------------------------------------

--  Some utilities for HTTP digest authentication

with GNAT.MD5;

package AWS.Digest is

   subtype Digest_String is GNAT.MD5.Message_Digest;

   subtype Nonce is String (1 .. 45);
   --  5 bytes hex seconds, 8 bytes hex global counter, 32 bytes digest
   --  of the creation date, seconds and global index.

   function Create_Nonce return Nonce;
   --  Create a Nonce value for the digest authentication
   --  see [RFC-2617 - 3.2.1]

   function Check_Nonce (Value : in String) return Boolean;
   --  Check Nonce for validity and expiration.
   --  We could not send a type Nonce here, because Nonce received from
   --  HTTP client, and have to checked for the length too.

   function Create
     (Username, Realm, Password : in String;
      Nonce                     : in String;
      Method, URI               : in String) return Digest_String;
   --  Returns a simple MD5 Digest

   function Create
     (Username, Realm, Password : in String;
      Nonce, NC, CNonce, QOP    : in String;
      Method, URI               : in String) return Digest_String;
   --  Returns a more complex MD5 Digest if QOP field is not empty

   function Tail
     (Nonce, NC, CNonce, QOP, Method, URI : in String) return String;
   --  Returns the precalculated tail part of the digest
   --  if QOP field is not empty
   --     Tail := ':' & Nonce & ':' & NC & ':' & CNonce & ':' & QOP & ':'
   --               & MD5.Digest (Method & ':' & URI);
   --  otherwise
   --     Tail := ':' & Nonce & ':' & MD5.Digest (Method & ':' & URI);

end AWS.Digest;
