我发现对于ntfs的文件和目录，有一个结构可以存储额外信息，加密的同志研究过否？

具体说明，可以在msdn中搜索以下reparse point。
以下是我贴的一段话：
Reparse Points
[This is preliminary documentation and subject to change.]

On an NTFS version 5.0 volume, a file or directory can contain a reparse point, which is a collection of user-defined data. The format of this data is understood by the application which stores the data, and a file system filter, which you install to interpret the data and process the file. When an application sets a reparse point, it stores this data, plus a reparse tag, which uniquely identifies the data it is storing. When the file system opens a file with a reparse point, it attempts to find the file system filter associated with the data format identified by the reparse tag. If such a file system filter is found, the filter processes the file as directed by the reparse data. If no such file system filter is found, the file open operation fails.

For example, in Windows NT 5.0, reparse points are used to implement NTFS links and the Microsoft Hierarchical Storage Management (HSM) Server. HSM Server uses an administrator-defined set of rules to move infrequently used files to long term storage, such as tape or CD-ROM. It uses reparse points to store information about the file in the file system. This information is stored in a stub file that contains a reparse point whose data points to the device where the actual file is now located. The file system filter can use this information to retrieve the file.

The following topics discuss reparse points:

Reparse Point Tags
Reparse Point Operations
Reparse Points and File Operations
Reparse Point Restrictions

确实应该放弃 :)

还是放弃修改文件本身吧，这个问题我已经尝试过了，行不通。

很冷清的 :)

也有人和我讲过NTFS的权限里面有几个位是空的，可以拿来用。但是后来我还是放弃了。
因为
1 NTFS特有的，FAT怎么办。现在FAT系统占的比例还是很大的呀。
2 系统位MS说不定那个补丁有用了。那时就傻了。

我现在也在研究怎么标记加密文件。我今天尝试在文件头加一个字符“T”。但是我测试了很多方法，读出来就是少一个字符。这样如果是文本等流文件还好，也许看不出来。有格式的文件如果少一个字符，整个就损坏。

我也没有办法了。

大家不是对改变文件长度无能为力吗？
不知道是否有用？