trans.h

伯克利做的SFTP安全文件传输协议

// trans.h
// new transformation interface; only considers one direction at a time
//   (security.h is *protocol* primitives,
//    trans.h is *cryptographic* primitives)
// copyright SafeTP Development Group, Inc., 2000  Terms of use are as specified in license.txt

#ifndef __TRANS_H
#define __TRANS_H

#include "typ.h"          // byte, bool

class DataBlock;          // datablok.h

// object to transform data
class Trans {
public:
  virtual ~Trans();

  // size relationships
  virtual int minInputSize() const;
    // minimum bytes of input
    // default: returns 0

  virtual int maxInputSize() const;
    // maximum bytes of input
    // default: returns MAXINT

  virtual int minOutputSize(int inputSize) const;
    // minimum bytes of output for a given input size
    // default: returns inputSize

  virtual int maxOutputSize(int inputSize) const;
    // maximum bytes of output for a given input size
    // default: returns inputSize

  // actual transform (in-place)
  virtual void trans(DataBlock &data);
    // changes 'data' to be the output
    // should call data.ensureAllocated(outputsize), to make sure the buffer
    //   will be big enough under any circumstances, but also take advantage
    //   of times when it already is
    // default: does nothing (identity transform)

  void checkingTrans(DataBlock &data);
    // same as 'trans', but min/maxOutputSize is verified
    // (for debugging purposes)
};


// a transform and its inverse
class TransPair {
public:
  Trans &encoder, &decoder;

public:
  TransPair(Trans &enc, Trans &dec)
    : encoder(enc), decoder(dec) {}

  // test that the transform+inverse pair == identity; returns true
  // if all tests succeed
  bool test(int randIters, bool echo=false);
  bool testBuffer(byte const *data, int length, bool echo=false);

  // initialize a non-crypto-strength random generator, for
  // calls to 'test'
  static void initRandom();
};

#endif // __TRANS_H