如何正确处理文件编码和解码？ [英] How to properly work with file upon encoding and decoding it?

问题描述

无论我如何精确地加密和解码文件。我使用文件作为 char large 操作，一切都差不多，直到我得到文件，其大小不分为8个字节。因为我可以加密和解码文件每个8字节，因为特定的算法质量（块的大小必须是64位）。

It doesn't matter how I exactly encrypt and decode files. I operate with file as a char massive, everything is almost fine, until I get file, which size is not divide to 8 bytes. Because I can encrypt and decode file each round 8 bytes, because of particular qualities of algorithm (size of block must be 64 bit).

那么，例如，我面对 .jpg ，并尝试在文件末尾添加空格，结果文件

So then, for example, I face .jpg and tried simply add spaces to end of file, result file can't be opened ( ofc. with .txt files nothing bad happen).

这里有什么办法吗？

如果您需要有关算法的信息 http://en.wikipedia.org/wiki/GOST_ （block_cipher）。

If you want information about algorithm http://en.wikipedia.org/wiki/GOST_(block_cipher).

UPD：我无法存储添加的字节数，因为可以删除初始文件移动。

UPD: I can't store how many bytes was added, because initial file can be deleted or moved. And, what we are suppose to do then we know only key and have encrypted file.

推荐答案

你需要填充。
执行此操作的最佳方法是使用 PKCS＃7 < a>。

Do you need padding. The best way to do this would be to use PKCS#7.

但是GOST不是那么好，更好的使用AES-CBC。
有一个类似的 python-channel中的讨论。

However GOST is not so good, better using AES-CBC. There is an ongoing similar discussion in "python-channel".

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