/* zx8 (ps) - Stream Cipher Algorithm/Source Code */

/*
Copyright (c) 2012, Karl-Uwe Frank
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
  documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#** zx8 (ps) algorithm developed by Karl-Uwe Frank
*/

#include <stdlib.h>
#include <stdio.h> 
#include <stdint.h>
#include <string.h>
#include <termios.h>
#include <time.h>



//-----------------------------------------
// 
// rm -f zx8_ps && gcc zx8_ps.c -o zx8_ps
// 
// ./zx8_ps -e Plainfile Cipherfile
// 
// ./zx8_ps -d Cipherfile Plainfile
// 
#include "zx8_ps_algorithm.c";


//-----------------------------------------
//
void ShowUsage(char* ThisName) 
{
    fprintf(stderr, "\nUsage: %s -e InFile OutFile     for encryption\n", ThisName);
    fprintf(stderr, "Usage: %s -d InFile OutFile     for decryption\n\n", ThisName);
}


//-----------------------------------------
// Invisible Keyboard Input
//
// http://www.undertec.de/blog/2009/05/
//
int getch() {
  static int ch = -1, fd = 0;
  
  struct termios neu, alt;
  
  fd = fileno(stdin);
  tcgetattr(fd, &alt);
  neu = alt;
  neu.c_lflag &= ~(ICANON|ECHO);
  tcsetattr(fd, TCSANOW, &neu);
  ch = getchar();
  tcsetattr(fd, TCSANOW, &alt);
  
  return ch;
}


//-----------------------------------------
// Main 
//
int main (int argc, char *argv[]) 
{ 
  // Check if a Parameter are passed through
  char* PrgName;
  char* InFile;
  char* OutFile;
  char  KeyComp[256];
  char* Direction;

  PrgName = argv[0];

  if (argc < 4) {
    ShowUsage(PrgName);
    return 1;
    
  } else {  
    Direction = argv[1];
    
    if ( (strcmp(Direction, "-e") != 0) && (strcmp(Direction, "-d") != 0) ) {
      ShowUsage(PrgName);
      return 1;
    }
    
    // Set InFile and OutFile Name
    InFile  = argv[2];
    OutFile = argv[3];
  }

  

  //-----------------------------------------
  //
  // Read the Encryption Keyword
  //
  int n;
  char c;    

  if (argc == 5) {
    // If passed as Parameter
    sprintf (KeyWord, "%s", argv[4]);
    KeyLen = strlen(KeyWord);
    } 
  else {
    printf ("Enter Keyword: ");
    n=0; c=0; while(c != '\n'){c=getch();KeyWord[n++]=c;};
    KeyWord[n-1]='\0';
    printf ("\n");
  
    if ( strcmp(Direction, "-e") == 0) {
      printf ("Enter Keyword again: ");
      n=0; c=0; while(c != '\n'){c=getch();KeyComp[n++]=c;};
      KeyComp[n-1]='\0';
      printf ("\n");
    
      if (strcmp(KeyWord, KeyComp) != 0) {
        printf ("Entered Keywords did not match\n\n");
        return 1;
      }
    }
  
    KeyLen = n-1;

    if ((KeyLen) < 8 ) {
      printf ("Keyword must be at least 8 unsigned characters long\n\n");
      return 1;
    }
  }

  printf ("Keyword is: %s\n", KeyWord);


  //-----------------------------------------
  // Initialisation of zx8 (ps)
  //
  // perform the Key Schedule
  KSA();


  unsigned int FileLen;
  unsigned char inB, outB;

  if (strcmp(Direction, "-e") == 0) {
    printf("===================================================\n");
    printf("Encrypting: %s\ninto file : %s\n", InFile, OutFile);
    printf("===================================================\n");
  } else {
  
    printf("===================================================\n");
    printf("Decrypting: %s\ninto file : %s\n", InFile, OutFile);
    printf("===================================================\n");
  }

  FILE* fIn = fopen(InFile, "rb");
  if (fIn == NULL) { printf("error opening file: %s\n", InFile); return -1; }
  
  fseek(fIn , 0 , SEEK_END);
  FileLen = ftell(fIn);
  rewind(fIn);

  FILE* fOut = fopen(OutFile, "wb");
  if (fOut == NULL) { printf("error creating file: %s\n", OutFile); return -1; }

  printf ("%10u byte file size\n", FileLen);


  // Encrypt/Decrypt Binary File (unbuffered Read/Write)
  while (fread(&inB, sizeof(char), 1, fIn)) {
    outB = inB ^ PRGA();
    fwrite(&outB, 1, 1, fOut);
  }
  
  return 0;   
}