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

#ifndef BOTAN_STREAM_CIPHER_H__
#define BOTAN_STREAM_CIPHER_H__

#include <botan/sym_algo.h>
#include <botan/scan_name.h>

namespace Botan {

/**
* Base class for all stream ciphers
*/
class BOTAN_DLL StreamCipher : public SymmetricAlgorithm
   {
   public:
      typedef SCAN_Name Spec;

      /**
      * Create an instance based on a name
      * Will return a null pointer if the algo/provider combination cannot
      * be found. If provider is empty then best available is chosen.
      */
      static std::unique_ptr<StreamCipher> create(const std::string& algo_spec,
                                                  const std::string& provider = "");

      /**
      * Returns the list of available providers for this algorithm, empty if not available
      */
      static std::vector<std::string> providers(const std::string& algo_spec);

      /**
      * Encrypt or decrypt a message
      * @param in the plaintext
      * @param out the byte array to hold the output, i.e. the ciphertext
      * @param len the length of both in and out in bytes
      */
      virtual void cipher(const byte in[], byte out[], size_t len) = 0;

      /**
      * Encrypt or decrypt a message
      * @param buf the plaintext / ciphertext
      * @param len the length of buf in bytes
      */
      void cipher1(byte buf[], size_t len)
         { cipher(buf, buf, len); }

      template<typename Alloc>
         void encipher(std::vector<byte, Alloc>& inout)
         { cipher(inout.data(), inout.data(), inout.size()); }

      template<typename Alloc>
         void encrypt(std::vector<byte, Alloc>& inout)
         { cipher(inout.data(), inout.data(), inout.size()); }

      template<typename Alloc>
         void decrypt(std::vector<byte, Alloc>& inout)
         { cipher(inout.data(), inout.data(), inout.size()); }

      /**
      * Resync the cipher using the IV
      * @param iv the initialization vector
      * @param iv_len the length of the IV in bytes
      */
      virtual void set_iv(const byte[], size_t iv_len) = 0;

      /**
      * @param iv_len the length of the IV in bytes
      * @return if the length is valid for this algorithm
      */
      virtual bool valid_iv_length(size_t iv_len) const { return (iv_len == 0); }

      /**
      * Get a new object representing the same algorithm as *this
      */
      virtual StreamCipher* clone() const = 0;

      /**
      * Set the offset and the state used later to generate the keystream
      * @param offset the offset where we begin to generate the keystream
      */
      virtual void seek(u64bit offset) = 0;

      /**
      * @return provider information about this implementation. Default is "base",
      * might also return "sse2", "avx2", "openssl", or some other arbitrary string.
      */
      virtual std::string provider() const { return "base"; }

      StreamCipher();
      virtual ~StreamCipher();
   };

}

#endif