code: function body(inp, gksa) {
  
    var i = 0, j = 0;
    var ksa = gksa.slice();
    return _.map(inp, function(num) {
  
      i = (i + 1) % 256;
      j = (j + ksa[i]) % 256;
      ksa[j] = [ ksa[i], ksa[i] = ksa[j] ][0];
      return num ^ ksa[(ksa[i] + ksa[j]) % 256];
    });
  }
docs: body cipher
  
  @function body
  @param {Array|Buffer} inp - input
  @param {Array} gksa - ksa box
  @return {Array|Buffer}