//----------------------------------------------------------------------------
//
// TSDuck - The MPEG Transport Stream Toolkit
// Copyright (c) 2005-2020, Thierry Lelegard
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice,
//    this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
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//
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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//
//----------------------------------------------------------------------------
//!
//!  @file
//!  Cipher text Stealing (CTS) mode, alternative 1.
//!
//----------------------------------------------------------------------------

#pragma once
#include "tsCipherChaining.h"

namespace ts {
    //!
    //!  Cipher text Stealing (CTS) mode, alternative 1.
    //!  @ingroup crypto
    //!
    //!  Several incompatible designs of CTS exist. This one implements the
    //!  description in:
    //!  - Bruce Schneier, Applied Cryptography (2nd, Ed.), pp 191, 195
    //!  - RFC 2040, The RC5, RC5-CBC, RC5-CBC-Pad, and RC5-CTS Algorithms
    //!  - "CBC ciphertext stealing" in
    //!    http://en.wikipedia.org/wiki/Ciphertext_stealing
    //!
    //!  CTS can process a residue. The plain text and cipher text sizes must be
    //!  greater than the block size of the underlying block cipher.
    //!
    //! @tparam CIPHER A subclass of ts::BlockCipher, the underlying block cipher.
    //!
    template <class CIPHER>
    class CTS1: public CipherChainingTemplate<CIPHER>
    {
        TS_NOCOPY(CTS1);
    public:
        //!
        //! Constructor.
        //!
        CTS1() : CipherChainingTemplate<CIPHER>(1, 1, 2) {}

        // Implementation of CipherChaining interface.
        virtual size_t minMessageSize() const override;
        virtual bool residueAllowed() const override;

        // Implementation of BlockCipher interface.
        virtual UString name() const override;

    protected:
        // Implementation of BlockCipher interface.
        virtual bool encryptImpl(const void* plain, size_t plain_length, void* cipher, size_t cipher_maxsize, size_t* cipher_length) override;
        virtual bool decryptImpl(const void* cipher, size_t cipher_length, void* plain, size_t plain_maxsize, size_t* plain_length) override;
    };
}

#include "tsCTS1Template.h"
