protected String getUserPuttyPrivateKey()
    {
    	BufferedReader br = null;
    	StringBuffer   sb = null;
    	
        try {
            if(hasUserPuttyKeyFile()) {
                File f = getUserPuttyKeyFile();
                br = new BufferedReader(new InputStreamReader(new FileInputStream(f)));
                sb = new StringBuffer();
                while(br.ready()) {
                    sb.append(br.readLine());
                    sb.append("\n");
                }

                return sb.toString();
            }
            else {
                throw new Error("Key file does not exist");
            }
        }
        catch(Exception e) {
            return null;
        }
        finally {
        	if(br != null) {        		
        		try { br.close(); } catch(Exception e) {}
        	}
        }
    }