sym_algo.h

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/*
* Symmetric Algorithm Base Class
* (C) 1999-2007 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
 
#ifndef BOTAN_SYMMETRIC_ALGORITHM_H__
#define BOTAN_SYMMETRIC_ALGORITHM_H__
 
#include <botan/algo_base.h>
#include <botan/key_spec.h>
#include <botan/exceptn.h>
#include <botan/symkey.h>
#include <botan/types.h>
 
namespace Botan {
 
/**
* This class represents a symmetric algorithm object.
*/
class BOTAN_DLL SymmetricAlgorithm : public Algorithm
   {
   public:
      /**
      * @return object describing limits on key size
      */
      virtual Key_Length_Specification key_spec() const = 0;
 
      /**
      * @return minimum allowed key length
      */
      size_t maximum_keylength() const
         {
         return key_spec().maximum_keylength();
         }
 
      /**
      * @return maxmium allowed key length
      */
      size_t minimum_keylength() const
         {
         return key_spec().minimum_keylength();
         }
 
      /**
      * Check whether a given key length is valid for this algorithm.
      * @param length the key length to be checked.
      * @return true if the key length is valid.
      */
      bool valid_keylength(size_t length) const
         {
         return key_spec().valid_keylength(length);
         }
 
      /**
      * Set the symmetric key of this object.
      * @param key the SymmetricKey to be set.
      */
      void set_key(const SymmetricKey& key)
         { set_key(key.begin(), key.length()); }
 
      /**
      * Set the symmetric key of this object.
      * @param key the to be set as a byte array.
      * @param length in bytes of key param
      */
      void set_key(const byte key[], size_t length)
         {
         if(!valid_keylength(length))
            throw Invalid_Key_Length(name(), length);
         key_schedule(key, length);
         }
   private:
      /**
      * Run the key schedule
      * @param key the key
      * @param length of key
      */
      virtual void key_schedule(const byte key[], size_t length) = 0;
   };
 
/**
* The two possible directions for cipher filters, determining whether they
* actually perform encryption or decryption.
*/
enum Cipher_Dir { ENCRYPTION, DECRYPTION };
 
}
 
#endif