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MD5 checksum question

wellmanwellman Registered Users Posts: 961 Major grins
Where does the MD5 checkum provided by the REST API come from? Does Smugmug actually calculate it on the server side when the appropriate API function is called, or is the checksum calculated on image upload and stored as a string in a database?

I ask because when I verify downloaded files in my little app (using the checksum), files from newer galleries pass the test, but the older the galleries get, the larger the failing percentage gets. When I look at these "failed" images, they look perfectly fine, but their local hashes just don't match the API's MD5 report.

If the MD5 hash is being called from a database, is it possible that a few bytes of data are being appended/changed in the JPGs as they move back and forth between Smugmug and Amazon S3? I'm just trying to figure out how a downloaded image can look perfectly fine and fail the MD5 hash.

Thanks,
Greg

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