=head1 Crypto handlers

Like with the L<database backends|database.html>, ermyth has modular crypto
facilities.

=head2 Writing a new crypto handler

Include the interface header

   #include "atheme.h"
   #include <ermyth/crypto.h>

Add the mandatory rcsid line

   static char const rcsid[] = "$Id: crypto.pod,v 1.1 2007/08/28 17:14:42 pippijn Exp $";

Define the handler

   namespace crypto
   {
     struct mycrypt : handler
     {
       mycrypt ()
       {
         crypto_module_loaded = true;
       }

       virtual ~mycrypt ()
       {
         crypto_module_loaded = false;
       }

       virtual char const *crypt (char const * const key, char const * const salt);
     };

     char const *
     mycrypt::crypt (char const * const key, char const * const salt)
     {
       // Our example merely reverses the string as encryption.
       std::reverse (key, key + strlen (key));
       return key;
     }
   } // namespace crypto

Register the handler

   #define FACREG_TYPE crypto::mycrypt
   #define FACREG_TYPE_NAME "mycrypt"
   #define FACREG_INTERFACE_TYPE crypto::handler
   #include <ermyth/factory_reg.h>

=head2 Using the handler

Now, we can load our crypto handler with the C<crypto> configuration directive:

   crypto "mycrypt";

Encrypting a string is as simple as invoking C<< crypter->crypt ("somestring", "salt") >>.
Our simple crypter doesn't use the salt, it just reverses the string and
returns "gnirtsemos".