//*********************************************//
//Encrypts text documents using a Vernam Cipher//
//So far, encrypts, doesn't yet decrypt********//
//Plus, has some bugs.  problems in comments***//
//********Zach Walton, 2005********************//
//*********************************************//
#include <iostream>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <time.h>
#include <iomanip>
using namespace std;
int main()
{
srand(time('\0'));
char alph[95] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ`1234567890-=~!@#$%^&*()_+[]\{}|;': ,./<>?";
char readbuffer[500],writebuffer[500],filename[50],bufferkey[500],;
int doclen=0,a=0, frlp, frlptwo, frlpthree, beginmenu, z=0, b=0;
begin:
cout << setw(10) << "Vernam Cipher Encryption System" << endl;
cout << setw(17) << "Developed by Zach Walton" << endl;
cout << "2005" << endl;
cout<<"\n";
cout<<"\n";
cout<<"\n";
cout << "1. Encrypt a file\n";
cout << "2. Decrypt a file\n";
cin >> beginmenu;
while(z!=1 && beginmenu!=2)
{
system ("cls");
cout << "Warning!  Will delete file named Key.txt.  If you wish to keep this file, move it to a different directory.\n";
system ("pause");
system("echo a > Key.txt");
system ("cls");
encrypt:
cout << "Input the filename (make sure to include extension!): ";
cin >> filename;
fstream file (filename);
if (! file.is_open())             //Checks for open file
{
      cout << "The file does not exist.  Did you type the extension?\n";
      system ("pause");
      system ("cls");
      goto encrypt;
}
while (! file.eof())            //finds document length
{
      file.getline(readbuffer,200);
      doclen = doclen+strlen(readbuffer);
}
char masterkey[doclen], filestr[doclen], encrypt[doclen];
int mastkint[doclen],filesint[doclen], encrypint[doclen];
for (frlp=0; frlp<(doclen); frlp++) //creates a random key equal to the document length
{
    a=rand()%94;
    masterkey[frlp]=alph[a];
}
if (strlen(masterkey)>doclen)    //stores NULL to each character longer than the document length- for error checking
{
for (frlp=doclen; frlp<strlen(masterkey); frlp++)
{
        masterkey[frlp]='\0';
}
}
frlptwo=0, frlpthree=frlptwo;
file.close();
fstream keytext ("Key.txt");
keytext << masterkey << endl;
keytext.close();
fstream filetwo (filename);
a=0;
while (! filetwo.eof() && b!=900)        //stores entire document to a variable (filestr)
    {
    filetwo.getline(readbuffer,200); 
    for (frlptwo; frlptwo<(frlpthree+strlen(readbuffer)); frlptwo++)
        {
        filestr[frlptwo]=readbuffer[a];
        a++;
        if (frlptwo==(doclen-1))
           b=900;
        }
    frlpthree=frlptwo;
    a=0;
    }
if (strlen(filestr)>doclen)                //stores NULL to each character in filestr over document length
{
for (frlp=doclen; frlp<strlen(filestr); frlp++)
{
        filestr[frlp]='\0';
}
}
remove(filename);                         //clears contents of old "Key.txt" file
filetwo.close();  
for (frlp=0; frlp<doclen; frlp++)         //converts characters to their respective numbers; problem probably here.
{
    for(a=0; a<95; a++)        //converts characters in masterkey to numbers in mastkint
    {
              if(masterkey[frlp]==alph[a])
               mastkint[frlp]=a;
    }
    for(a=0; a<95; a++)    //converts characters in filestr to numbers in filesint
    {
             if(filestr[frlp]==alph[a])
             filesint[frlp]=a;
    }
}
for (frlp=0; frlp<doclen; frlp++)  //subtracts number in filesint from number in mastkint.
                                   //if negative, converts to positive.
                                   //requires understanding of vernam cipher
{
    encrypint[frlp]=mastkint[frlp]-filesint[frlp];
    if (encrypint[frlp]<0)
    encrypint[frlp]=encrypint[frlp]*-1;
}
for (frlp=0; frlp<doclen; frlp++) //converts encrypint to its related character; final encrypted text
{
    a=encrypint[frlp];
    encrypt[frlp]=alph[a];
}
if (strlen(encrypt)>doclen)
{
for (frlp=doclen; frlp<strlen(encrypt); frlp++) //stores NULL to all characters in encrypt longer than doclen
{
        encrypt[frlp]='\0';
}
}

fstream enc (filename);
enc << encrypt << endl;                    //stores encrypted text to the original document
cout << "File succesfully encrypted!\n";
z++;
}
/*
/
/
//END ENCRYPTION SECTION
//BEGIN DECRYPTION SECTION
/
/
*/
while(z!=1 && beginmenu!=1)
{
decrypta:
system ("cls");
cout << "Make sure that both Key.txt and the desired file to be decrypted are in the same directory as the program, and input the name of the file to be decrypted(Don't forget the extension!): ";
cin >> filename;
fstream dfile (filename);  //loads file to be decrypted  
if (! dfile.is_open())     //error check- is file open?
{
      cout << "The file does not exist.\n";
      system ("pause");
      goto decrypta;
}
decrypt:
while (! dfile.eof())  //finds document length of file
{
      dfile.getline (readbuffer,200);
      doclen = doclen+strlen(readbuffer);
}
dfile.close();
char dkey[doclen], dfileu[doclen], decrypt[doclen];
int dkint[doclen], dfint[doclen], dalcomp[doclen];
frlptwo=0, frlpthree=frlptwo;
fstream dfiletwo (filename);       //re-declares the file
while (! dfiletwo.eof() && b!=900) //stores contents of file to a string (dfileu)
    {
    dfiletwo.getline(readbuffer,200); 
    for (frlptwo; frlptwo<(frlpthree+strlen(readbuffer)); frlptwo++)
        {
        dfileu[frlptwo]=readbuffer[a];
        a++;
        if (frlptwo==(doclen-1))
           b=900;
        }
    frlpthree=frlptwo;
    a=0;
    }
dfiletwo.close();
b=0;
if (strlen(dfileu)>doclen)  //error check; stores NULL to extra characters
{
for (frlp=doclen; frlp<strlen(dfileu); frlp++)
{
        dfileu[frlp]='\0';
}
}
fstream dkeyfile ("Key.txt");  //loads the key file
a=0, frlptwo=0, frlpthree=frlptwo;
while (! dkeyfile.eof() && b!=900) //stores the key file to a string
    {
    dkeyfile.getline(readbuffer,200); 
    for (frlptwo; frlptwo<(frlpthree+strlen(readbuffer)); frlptwo++)
        {
        dkey[frlptwo]=readbuffer[a];
        a++;
        if (frlptwo>doclen)
           b=900;
        }
    frlpthree=frlptwo;
    a=0;
    }
dkeyfile.close();
if (strlen(dkey)>doclen) //error check; stores NULL to extra characters
{
for (frlp=doclen; frlp<strlen(dkey); frlp++)
{
        dkey[frlp]='\0';
}
}
for (frlp=0; frlp<doclen; frlp++) //converts both strings to their numeric equivalents
{
    for(a=0; a<95; a++) //converts characters in dkey to their numeric equivalents, stores in dkint
    {
              if(dkey[frlp]==alph[a])
               dkint[frlp]=a;
    }
    for(a=0; a<95; a++)//converts characters in dfileu to their numeric equivalents, stores in dfint
    {
             if(dfileu[frlp]==alph[a])
             dfint[frlp]=a;
    }
}
for (frlp=0; frlp<doclen; frlp++) //subtracts dfint[x] from dkint[x], multiplies negatives by -1, stores result to dalcomp
{
    dalcomp[frlp]=dkint[frlp]-dfint[frlp];
    if (dalcomp[frlp]<0)
    dalcomp[frlp]=dalcomp[frlp]*-1;
}
for (frlp=0; frlp<doclen; frlp++) //converts numbers in dalcomp to their character equivalents, stores to decrypt (final decrypted text)
{
    a = dalcomp[frlp];
    decrypt[frlp]=alph[a];
}
if (strlen(decrypt)>doclen) //error check; stores NULL to extra characters
{
for (frlp=doclen; frlp<strlen(decrypt); frlp++)
{
        decrypt[frlp]='\0';
}
}
fstream decrypted (filename);
decrypted << decrypt << endl; //stores decrypted text to original encrypted document
cout << "File successfully decrypted!\n";
cout << "" << endl;
z++;
}
//END DECRYPTION SECTION
system ("pause");
}

key['a'] = 0;
key['b'] = 1;
key['D'] = 29;
key['P'] = 41;
key[':'] = 86;
etc

key['b']=1;

key['b']=1;
if (k=key[1])
cout << key[1] << endl;

key[98]=1;

encrypt['a'] = 0;
encrypt['b'] = 1;
encrypt['c'] = 2;
encrypt['d'] = 3;
encrypt['e'] = 4;
  etc.