I’m delighted to announce the first release version of Dintch, my free utility for checking the integrity of files on your Mac and its archival storage.
Unlike other similar utilities for checking file integrity, Dintch works by calculating a SHA-256 ‘digest’, which functions as a unique fingerprint for each file, and attaches that to the file itself as an extended attribute. This means that wherever that file goes, it takes that fingerprint with it, and its integrity can be checked again and again.
This version has one major improvement over the previous beta-release: it now has a more conservative Retag feature which lets you refresh only those tags which have changed. This minimises the number of files which require backing up by Time Machine. It also fixes a bug in which buffer size settings weren’t always saved when quitting the app, and its documentation has been greatly extended.
This version of Dintch works on folders rather than letting you tag files one at a time. To tag a folder, simply click on its Tag button, select the folder, and Dintch will then tag all the files (and files within nested folders) with their digests.
If some of the files in that folder have their tags removed or are changed by apps, then you can now Retag that folder. This works through the folder and all its contents checking whether each file’s digest matches that saved with it. If there’s no previous tag, then it attaches a new tag. If the digest has changed, it writes the new digest to the tag. If the digest matches that saved in the existing tag, then Dintch leaves that file alone, so it isn’t backed up again by Time Machine.
When you want to check the integrity of your files, simply click on the Check button and select the folder. Dintch will then report all those files whose data has been changed.
Tags are normally preserved when copying or moving files between local volumes which use HFS+ or APFS file systems (and on some others). They’re also preserved when copied or moved to iCloud, including using iCloud to copy them to another Mac. Some other cloud services don’t preserve the tags, though. They also travel across network transfers, including AirDrop.
Dintch works in all versions of macOS from El Capitan to Catalina, and its tags are compatible across different versions of macOS too. It features an adjustable buffer size, with which you can tune it to work quickest with different file sizes.