function ARC4()

in tool/seedrandom.js [141:183]

• 3 lines of code
• 3 McCabe index (conditional complexity)

  function ARC4(key) {
    var t,
      keylen = key.length,
      me = this,
      i = 0,
      j = (me.i = me.j = 0),
      s = (me.S = []);

    // The empty key [] is treated as [0].
    if (!keylen) {
      key = [keylen++];
    }

    // Set up S using the standard key scheduling algorithm.
    while (i < width) {
      s[i] = i++;
    }
    for (i = 0; i < width; i++) {
      s[i] = s[(j = mask & (j + key[i % keylen] + (t = s[i])))];
      s[j] = t;
    }

    // The "g" method returns the next (count) outputs as one number.
    (me.g = function (count) {
      // Using instance members instead of closure state nearly doubles speed.
      var t,
        r = 0,
        i = me.i,
        j = me.j,
        s = me.S;
      while (count--) {
        t = s[(i = mask & (i + 1))];
        r =
          r * width + s[mask & ((s[i] = s[(j = mask & (j + t))]) + (s[j] = t))];
      }
      me.i = i;
      me.j = j;
      return r;
      // For robust unpredictability, the function call below automatically
      // discards an initial batch of values.  This is called RC4-drop[256].
      // See http://google.com/search?q=rsa+fluhrer+response&btnI
    })(width);
  }