pam_radius_auth.c

 

 if (password) {
   get_random_vector(request->vector);
   if (old_password) { /* password change request */
     add_password(request, PW_PASSWORD, password, old_password);
     add_password(request, PW_OLD_PASSWORD, old_password, old_password);
   } else {  /* authentication request */
     add_password(request, PW_PASSWORD, password, server->secret);
   }
 }

Why change secret key?

 

old password -> secret key ??