CTR.h

/*
 * Copyright (C) 2015 Southern Storm Software, Pty Ltd.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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 * DEALINGS IN THE SOFTWARE.
 */

#ifndef CRYPTO_CTR_h
#define CRYPTO_CTR_h

#include "Cipher.h"
#include "BlockCipher.h"

class CTRCommon : public Cipher
{
public:
    virtual ~CTRCommon();

    size_t keySize() const;
    size_t ivSize() const;

    bool setCounterSize(size_t size);

    bool setKey(const uint8_t *key, size_t len);
    bool setIV(const uint8_t *iv, size_t len);

    void encrypt(uint8_t *output, const uint8_t *input, size_t len);
    void decrypt(uint8_t *output, const uint8_t *input, size_t len);

    void clear();

protected:
    CTRCommon();
    void setBlockCipher(BlockCipher *cipher) { blockCipher = cipher; }

private:
    BlockCipher *blockCipher;
    uint8_t counter[16];
    uint8_t state[16];
    uint8_t posn;
    uint8_t counterStart;
};

template <typename T>
class CTR : public CTRCommon
{
public:
    CTR() { setBlockCipher(&cipher); }

private:
    T cipher;
};

#endif