Playing around with ciphers

crypto

#!/usr/bin/env node

var operation = process.argv[process.argv.length - 1];
var allowed = '--decipher --cipher'

if(allowed.indexOf(operation) === -1) {
  operation = '--cipher';
}

// let us type a string

process.stdin.resume();

process.stdin.on('data', function(data) {
  process.stdin.pause();

  var ops = {};
  
  ops['--cipher'] = cipher;
  ops['--decipher'] = decipher;

  ops[operation].call(this, data.toString());  
});


// var real = ' abcdefghijklmnopqrstuvwxyz1234567890!@#$%^&*()_+';

var i = 0
  , real = '\n'
;

while(i++ <= 512) {
  var v = String.fromCharCode(i);
  v && (real += v);
  
  var vv = String.fromCharCode(1024 - i);
  vv && (real += vv);
}


var original = {};
var originalChars = [];
var index = 0;

real.split('').forEach(function(letter) {
  originalChars[index] = letter;
  original[letter] = index;
  
  index++;
});

function cipher(str) {
  var chars = str.split('');
  var result = [];
  
  var letter;
  var shift = 1;
  
  while(letter = chars.shift()) {
    var ind = original[letter] + shift;
    
    if(ind > originalChars.length) {
      ind = 0;
      shift = 0;
    }
    
    shift++;
    
    var ciphered = originalChars[ind];
    
    result.push(ciphered); 
  }
  
  process.stdout.write(result.join(''));
  process.stdout.write('\n');
}

function decipher(str) {
  var chars = str.split('');
  var result = [];
  
  var letter;
  var shift = 1;
  
  while(letter = chars.shift()) {
    var ind = original[letter] - shift;
    
    if(ind > originalChars.length) {
      ind = 0;
      shift = 0;
    }
    
    shift++;
    
    var ciphered = originalChars[ind];
    
    result.push(ciphered); 
  }
  
  process.stdout.write(result.join(''));
  process.stdout.write('\n');
}

example.sh

# input
$ ./crypto
testing 123456 aaaaaaaa
ΌfΌvΕqΖ$ϋ7ψ:υ=ϙiΗjΖkΕlΔ

# output
$ ./crypto --decipher
ΌfΌvΕqΖ$ϋ7ψ:υ=ϙiΗjΖkΕlΔ
testing 123456 aaaaaaaa

# pipes
$ cat > secret.txt
hey this is secret!
^C
$ cat secret.txt 
hey this is secret!
$ cat secret.txt | ./crypto
ΘfΆ"ΊkΔwϜnΈ&·lΖzΓ}ϖϬ
$ cat secret.txt | ./crypto | ./crypto --decipher
hey this is secret!