Question Checksum

[ben]

Hello,

i would like to get a checksum for some files (images and videos).
I found the variable {File.CRC} in the help.

Does this variable include the metadata?
Does this work for videofiles and also images (i am not using raw images)?
Is there another checksome stored with each file that should be favoured?

Thanks a lot for your help
Ben

[Mario]

This is a 32-bit CRC checksum for the entire file. The checksum (in combination with the size) is identical for two files if they are binary identical.
When I would redo IMatch, I would switch to SHA256 checksum, which are more reliable, but more computing-intensive. For the purpose of IMatch to detect dupes, the 32-bit CRC works well (in combination with the file size).

IMatch includes the File Verifier app which allows you to check if a file has been modified on disk without changing the file system timeouts (corruption, bit rot or rogue software).

When you install the cool 7-Zip software, you get a new menu entry in the Windows Explorer context menu which allows you to create all kinds of checksums for your files.

In Windows, you can create checkums for files on the command line:

certUtil -hashfile C:\data\myimage.jpg SHA256

[ben]

Thanks a lot for your information
The 32-bit CRC will work for me as well.

[Mario]

Always use it in combination with file size to make it more reliable.