/*
* Engine
* (C) 1999-2007 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#ifndef BOTAN_ENGINE_H__
#define BOTAN_ENGINE_H__

#include <botan/scan_name.h>
#include <botan/block_cipher.h>
#include <botan/stream_cipher.h>
#include <botan/hash.h>
#include <botan/mac.h>
#include <botan/pbkdf.h>
#include <botan/pow_mod.h>
#include <botan/pk_keys.h>
#include <botan/pk_ops.h>

namespace Botan {

class Algorithm_Factory;
class Keyed_Filter;
class RandomNumberGenerator;

/**
* Base class for all engines. All non-pure virtual functions simply
* return NULL, indicating the algorithm in question is not
* supported. Subclasses can reimplement whichever function(s)
* they want to hook in a particular type.
*/
class BOTAN_DLL Engine
   {
   public:
      virtual ~Engine() {}

      /**
      * @return name of this engine
      */
      virtual std::string provider_name() const = 0;

      /**
      * @param algo_spec the algorithm name/specification
      * @param af an algorithm factory object
      * @return newly allocated object, or NULL
      */
      virtual BlockCipher*
         find_block_cipher(const SCAN_Name& algo_spec,
                           Algorithm_Factory& af) const;

      /**
      * @param algo_spec the algorithm name/specification
      * @param af an algorithm factory object
      * @return newly allocated object, or NULL
      */
      virtual StreamCipher*
         find_stream_cipher(const SCAN_Name& algo_spec,
                            Algorithm_Factory& af) const;

      /**
      * @param algo_spec the algorithm name/specification
      * @param af an algorithm factory object
      * @return newly allocated object, or NULL
      */
      virtual HashFunction*
         find_hash(const SCAN_Name& algo_spec,
                   Algorithm_Factory& af) const;

      /**
      * @param algo_spec the algorithm name/specification
      * @param af an algorithm factory object
      * @return newly allocated object, or NULL
      */
      virtual MessageAuthenticationCode*
         find_mac(const SCAN_Name& algo_spec,
                  Algorithm_Factory& af) const;

      /**
      * @param algo_spec the algorithm name/specification
      * @param af an algorithm factory object
      * @return newly allocated object, or NULL
      */
      virtual PBKDF* find_pbkdf(const SCAN_Name& algo_spec,
                                Algorithm_Factory& af) const;

      /**
      * @param n the modulus
      * @param hints any use hints
      * @return newly allocated object, or NULL
      */
      virtual Modular_Exponentiator*
         mod_exp(const BigInt& n,
                 Power_Mod::Usage_Hints hints) const;

      /**
      * Return a new cipher object
      * @param algo_spec the algorithm name/specification
      * @param dir specifies if encryption or decryption is desired
      * @param af an algorithm factory object
      * @return newly allocated object, or NULL
      */
      virtual Keyed_Filter* get_cipher(const std::string& algo_spec,
                                       Cipher_Dir dir,
                                       Algorithm_Factory& af);

      /**
      * Return a new operator object for this key, if possible
      * @param key the key we want an operator for
      * @return newly allocated operator object, or NULL
      */
      virtual PK_Ops::Key_Agreement*
         get_key_agreement_op(const Private_Key& key, RandomNumberGenerator& rng) const;

      /**
      * Return a new operator object for this key, if possible
      * @param key the key we want an operator for
      * @return newly allocated operator object, or NULL
      */
      virtual PK_Ops::Signature*
         get_signature_op(const Private_Key& key, const std::string& hash, RandomNumberGenerator& rng) const;

      /**
      * Return a new operator object for this key, if possible
      * @param key the key we want an operator for
      * @return newly allocated operator object, or NULL
      */
      virtual PK_Ops::Verification*
         get_verify_op(const Public_Key& key, const std::string& hash, RandomNumberGenerator& rng) const;

      /**
      * Return a new operator object for this key, if possible
      * @param key the key we want an operator for
      * @return newly allocated operator object, or NULL
      */
      virtual PK_Ops::Encryption*
         get_encryption_op(const Public_Key& key, RandomNumberGenerator& rng) const;

      /**
      * Return a new operator object for this key, if possible
      * @param key the key we want an operator for
      * @return newly allocated operator object, or NULL
      */
      virtual PK_Ops::Decryption*
         get_decryption_op(const Private_Key& key, RandomNumberGenerator& rng) const;
   };

}

#endif