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Ask HN: What is the best way to verify image, video and pdf scan modification?

2 points by igib ↗ HN
Hello,

I have fair few images, videos and pdf scans coming through. I need to verify whether they have been digitally modified in any way. I would prefer a service with an api however software package will do as long as its good. Something that doesnt cost arm and a leg would be preferable.

Cheers

3 comments

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privong
I think you might need to provide more details. Where are the scans "coming through", what type of modifications are you trying to detect, and at what points in the process might those modifications occur?
igib
Files are uploaded by users. I am trying to detect any modification that has occurred after the original image, video or scan has been captured therefore any modifications made by the users prior to upload. Eg. User takes a photo, modifies it, uploads it, I scan it (with required software/service), tells me its modified.

Cheers

MalcolmDiggs
Many programming languages have some sort of file-to-hash function built in. PHP has md5_file(), python has hashlib.md5(), etc.

I believe the easiest way to accomplish your goal is to get the md5 hash of the file before and after and compare the two results.