如何获得windows phone 8.1的设备唯一Id ?

我想要唯一的设备Id为后端服务(ws)，我发现以下参考

  private string GetDeviceId()
    {
        var token = Windows.System.Profile.HardwareIdentification.GetPackageSpecificToken(null);
        var hardwareId = token.Id;
        var dataReader = Windows.Storage.Streams.DataReader.FromBuffer(hardwareId);
        byte[] bytes = new byte[hardwareId.Length];
        dataReader.ReadBytes(bytes);
        return BitConverter.ToString(bytes).Replace("-", "");
    }//Note: This function may throw an exception. 

但是，我无法理解代码，每次我得到相同的Id为我的设备(64个字符串)，我想知道它是否适用?我在MSDN上也找不到任何参考

Thank you

private string GetDeviceID()
{
    HardwareToken token = HardwareIdentification.GetPackageSpecificToken(null);
    IBuffer hardwareId = token.Id;
    HashAlgorithmProvider hasher = HashAlgorithmProvider.OpenAlgorithm(HashAlgorithmNames.Md5);
    IBuffer hashed = hasher.HashData(hardwareId);
    string hashedString = CryptographicBuffer.EncodeToHexString(hashed);
    return hashedString;
}