docs: function (arr, _noEquals, _url) {
      var out = "", i, bits=0, c = sjcl.codec.base64._chars, ta=0, bl = sjcl.bitArray.bitLength(arr);
      if (_url) {
        c = c.substr(0,62) + '-_';
      }
      for (i=0; out.length * 6 < bl; ) {
        out += c.charAt((ta ^ arr[i]>>>bits) >>> 26);
        if (bits < 6) {
          ta = arr[i] << (6-bits);
          bits += 26;
          i++;
        } else {
          ta <<= 6;
          bits -= 6;
        }
      }
      while ((out.length & 3) && !_noEquals) { out += "="; }
      return out;
    }