code: function body(inp, ksa, prga, container, length) {
  
    var i = 0, j1 = 0, j2 = 0;
    var out = container;
    var s1 = ksa.slice();
    var s2 = prga.slice();
    for (var y = 0; y < length; ++y) {
      i = (i + 1) % 256;
      j1 = (j1 + s1[i]) % 256;
      s1[j1] = [ s1[i], s1[i] = s1[j1] ][0];
      out[y] = inp[y] ^ s2[(s1[i] + s1[j1]) % 256];
      if (++y < length) {
        j2 = (j2 + s2[i]) % 256;
        s2[j2] = [ s2[i], s2[i] = s2[j2] ][0];
        out[y] = inp[y] ^ s1[(s2[i] + s2[j1]) % 256];
      }
    }
  
    return out;
  }
docs: Body cipher.
  
  @function body
  @param {Array|Buffer} inp - input
  @param {Array} ksa - ksa box
  @param {Array} prga - prga box
  @param {Array|Buffer} container - out container
  @param {Integer} length - limit
  @return {Array|Buffer}