include/wvcountermode.h

   1 /* -*- Mode: C++ -*-
   2  * Worldvisions Tunnel Vision Software:
   3  *   Copyright (C) 1997-2002 Net Integration Technologies, Inc.
   4  *
   5  * A 'counter mode' cryptography engine abstraction.
   6  */
   7 #ifndef __WVCOUNTERMODE_H
   8 #define __WVCOUNTERMODE_H
   9
  10 #include "wvencoder.h"
  11
  12 /** A counter mode encryption encoder. */
  13 class WvCounterModeEncoder : public WvEncoder
  14 {
  15 public:
  16     WvEncoder *keycrypt;
  17
  18     /**
  19      * Create a new counter mode encoder / decoder.
  20      *   _keycrypt    : the underlying encoder for generating the keystream
  21      *                  (note: takes ownership of this encoder)
  22      *   _counter     : the initial counter value
  23      *   _countersize : the counter size, must equal crypto block size
  24      */
  25     WvCounterModeEncoder(WvEncoder *_keycrypt,
  26         const void *_counter, size_t _countersize);
  27     virtual ~WvCounterModeEncoder();
  28
  29     /**
  30      * Sets the Counter mode auto-incrementing counter.
  31      *   counter     : the counter
  32      *   countersize : the new counter size, must equal crypto block size
  33      */
  34     void setcounter(const void *counter, size_t countersize);
  35
  36     /**
  37      * Stores the current counter in the supplied buffer.
  38      *   counter : the array that receives the counter
  39      */
  40     void getcounter(void *counter) const;
  41
  42     /** Returns the counter size. */
  43     size_t getcountersize() const
  44         { return countersize; }
  45
  46     /** Increments the counter. */
  47     virtual void incrcounter();
  48
  49 private:
  50     WvConstInPlaceBuf counterbuf;
  51
  52 protected:
  53     unsigned char *counter; // auto-incrementing counter
  54     size_t countersize; // counter size in bytes
  55
  56     virtual bool _encode(WvBuf &inbuf, WvBuf &outbuf, bool flush);
  57 };
  58
  59 #endif // __WVCOUNTERMODE_H