FYI, redaction from pdf can be similarly difficult. I once was tangentially involved with a pdf redaction piece of software, and due to many different issues wi

FYI, redaction from pdf can be similarly difficult. I once was tangentially involved with a pdf redaction piece of software, and due to many different issues with pdf, the solution ended up being to create images of the input pdf draw over the redacted info, then create/overwrite a new pdf that was just a container for the jpgs. It was the only way to be sure the info wasn’t in the pdf at all, since it could be all kinds of places and duplicated in interesting ways. But since you’d be working on the final rendering you could be sure everything you covered would be covered in the final output. The biggest challenges after that were related to text extraction, since we wanted a nice UI where you could select text and the redaction would auto cover text and use a uniform width based on the heights of all characters in the redaction. I think more often than we were happy with a user would need to simply use a bounding box since extracting all the pertinent data related to the text was so hard. I walked away from the product over a decade ago since it always seemed like it’d be trivial for adobe to implement the feature in reader. Though every couple of years there’s a redaction scandal and I keep wondering how lucrative the product could have been with some marketing.