I have files with different extensions, some are text files, others are zipped files or images. How can I programmatically add a checksum to the files?

For example, my idea was to add a checksum somewhere in the metadata of the files. I tried doing it with PowerShell, but the properties of the files are read-only. I don't want to create a separate file that contains the checksum of the files. I want the checksum itself to be included somewhere in the file itself or in its metadata.

CodePudding user response：

On Windows, with NTFS filesystem, you can use Alternate Data Streams.

They act exactly like files, but hidden and attached to the main file - until it's copied on a non-NTFS partition.

Otherwise, you can't just add a checksum to a file (even a short CRC32) without consequences, and how would you be SURE that the last N bytes are your checksum, and not file's data? You'll need to add a header (so even more bytes), etc. and it can mess up the file loading - simply think about a simple, plain text file, if you add N bytes of binary data at end!