function cryptCharcode(n, start, end, offset) {
  n = n + offset;
  if (offset > 0 && n > end) {
    n = start + (n - end - 1);
  } else if (offset < 0 && n < start) {
    n = end - (start - n - 1);
  }
  return String.fromCharCode(n);
}

function cryptString(enc, offset) {
  var dec = "";
  var len = enc.length;
  for(var i=0; i < len; i++) {
    var n = enc.charCodeAt(i);
    if (n >= 0x2B && n <= 0x3A) {
      dec += cryptCharcode(n, 0x2B, 0x3A, offset);
    } else if (n >= 0x40 && n <= 0x5A) {
      dec += cryptCharcode(n, 0x40, 0x5A, offset);
    } else if (n >= 0x61 && n <= 0x7A) {
      dec += cryptCharcode(n, 0x61, 0x7A, offset);
    } else {
      dec += enc.charAt(i);
    }
  }
  return dec;
}

function decryptMailto(s) {
  location.href = cryptString(s, -7);
}