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Posted by 1317 2 days ago

PDF Forgeries Are Surprisingly Rare (2022)(gwern.net)
55 points | 46 comments
tristanj 20 hours ago|
I think a big reason for this is that PDF editing tools are just pretty terrible.

PDFs are meant to be a presentation document format, not an editable document format. I have some experience editing PDFs, and it's difficult to make significant modifications. Editing small sections of text or replacing a date is fine, but once you try to start editing entire paragraphs or changing the layout, it quickly becomes unmanageable. The kerning looks weird, the spacing between words looks off, and when you look into it you realize the the sentence you're trying to edit is actually split across a dozen text objects. For these it becomes almost impossible to edit without destroying the spacing, so you just give up.

And the approved way to edit these PDFs is via Adobe Acrobat Pro, which costs $20/month (ugh), which I'm not willing to pay for.

So I think this is why we just don't see that many PDF forgeries. The editing tools just aren't very good. Maybe it's different now we can just ask Claude to edit our PDFs for us.

slybot 19 hours ago||
PDF's are not Presentation Document Format. Should be "Portable".
ozim 15 hours ago|||
Main point of parent still stands - PDF's are not meant to be edited one should generate new from the source material and that's it.
marysol5 13 hours ago||||
They're "portable" in that they can be "universally" read. Not that you can create and manage them.
slybot 19 hours ago|||
[flagged]
mamonoleechi 14 hours ago|||
>I think a big reason for this is that PDF editing tools are just pretty terrible.

Inkscape is a pretty good tool to edit .pdfs

when you import a regular .pdf, it needs to convert it once, and once saved, you can edit the pdf and work on it as if it was a regular .svg

if you choose to embed the fonts when saving, .pdf files becomes easy to work on, you don't even need to export them.

marysol5 13 hours ago||
Editing PDF's is worse than editing documents in Microsoft Word!

Even generating them on the fly can be a real pain. I had a workflow when I was out of work to auto-generate a CV based upon re-writing sections to match the spec. So I'd have pre-written blocks and slot them in. And yet, somehow, even then it would break formatting all over the place.

sjtgraham 19 hours ago||
I agree that you won't find forged PDF documents in the wild with any type of frequency, but they are forged in private settings. Forged or doctored bank statements are relatively more common. FinCEN identifies altered bank statements alongside W-2s, tax returns, gift letters, and employment information as examples of documents involved in mortgage fraud [1]. In March 2026, a mortgage loan officer was even charged by federal prosecutors with altering and creating bank statements to make borrowers appear qualified for a mortgage [2].

[1] https://www.fincen.gov/mortgage-loan-fraud

[2] https://www.justice.gov/usao-mdfl/pr/licensed-mortgage-loan-...

rithdmc 14 hours ago||
I can't find the quote any more, but when some internal bank workers were done for laundering money (possibly the Estonian branch of Danske Bank), one of the messages between the defendants read "There's always photoshop" :)
yieldcrv 17 hours ago||
I saw it alot in the fake KYC world, phantom commodities trades

and all those things listed wouldn’t be prosecuted, as long as you don’t touch mortgages

I would say KYC in general is a joke and nobody cares, as long as FinCEN and the DOJ believe KYC is working. But as far as the peddling of forged PDF’s go, very common, just not at the point of where the more damaging crime occurs ….. except in mortgage fraud, where that crime explicitly considers the fake employment letter to be the crime

exmadscientist 19 hours ago||
The flip side to this is that when you do come across a forged PDF (and I have!), they can be really, really effective. Nobody expects them. There are usually tells in the metadata, but... there don't have to be.
mjg59 20 hours ago||
Not quite the scenario described (it wasn't an academic paper), but https://mjg59.dreamwidth.org/73317.html is my experience of dealing with a forged PDF. Part of the reason it's rare is that it's actually very hard to do it well!
anitil 20 hours ago||
I believe it's actually linked in the OP about half way down. What a crazy thing for an agent to do - to turn a minor disagreement into a maybe-crime.
jstanley 17 hours ago|||
Are you saying that RightSignature puts the checksum information inside the document and therefore destroys the checksum? What is the thinking behind that?
arjvik 20 hours ago||
was linked in the article!
ValdikSS 10 hours ago||
There's entire industry to detect PDF forgeries. They analyze how exactly each software acts upon editing the file and detect these features.

Some software rewrap the page into say additional XObject, some add unique elements, some change one IDs but not the others.

I had a great blog post about it but can't find it right now. Will post if find the link.

broken-kebab 13 hours ago||
PDFs are being forged everyday, mostly for financial incentives. The reason it rarely happens with scienific papers (as seems to be a particular concern of the author) is because it makes not much practical sense.

1. General public don't read papers.

2. General public have lowered trust to them.

3. It's not impossible to produce and publish genuine paper with forged data.

laserbeam 14 hours ago||
I'd say the reason for this is that PDFs are not viral like images or videos. I don't think any of the technical arguments are strong enough.

If you want to forge a PDF, you do it because you have a private target in mind. Financial fraud, corporate espionage... There are other settings but people don't just share PDFs around for you to see a deluge of fake ones.

rithdmc 14 hours ago|
I believe that some of the DNC (and other hack & leak) documents were tampered with. Does anyone remember if that included pdfs?
marysol5 13 hours ago||
One was a word doc they added "Confidential" to the footer, then released as PDF
arethuza 17 hours ago||
Forged and modified PDFs were definitely a problem in some commercial areas that I used to work in (this was about 15 years ago).
reddalo 15 hours ago||
They still are. I know some people who got software packages for free because they "proved" to be university students by submitting a forged PDF.
zarzavat 15 hours ago||
Why commit copyright infringement when you could commit criminal fraud instead?!
dist-epoch 15 hours ago||
Sometimes the software is just not available online, or it doesn't work well if cracked.

Students giving out free Microsoft licenses they could access through their University to people they knew was a thing, because Microsoft activation hacks had all kinds of problems.

cucumber3732842 14 hours ago||
There are obscene amounts of "forged" stamped surveys and engineering drawings floating around.

Not like altering lines or anything material (I can already imagine the breathless replies being typed about how it's "antisocial" if someone's deck doesn't meet setbacks by 1ft or something) but changing text to remove references that would indicate other survey work was done that they don't wanna submit to public record, changing a labeled distance by a couple feet to make something that already exists technically compliant.

Like with everything else it's the little guys sticking their necks out. The big guys can afford good surveyors who "get it" and don't need to be told when a difference within the bounds of measurement error and will have four or five figure implications or that a survey result is so unfavorable that they should just call the client, bill whatever they would have charged as a consulting fee and not screw their client with the liability of a paper trail.

eru 20 hours ago||
Gwern, in case you are reading this, there's a typo in:

> (In the rare cases anyone tampers with PDFs, it quickly turns into a technical morass and he-said-she-said, and requires several orders of magnitude more effort to prove than to do; consider the hoops epxperts had to jump through in the Craig Wright cases, or even just a landlord editing a contract—where the contract was done through a digital document timestamping service!)

Specifically "epxperts"

black_knight 17 hours ago|
Typos are so easy to weed out these days, I assume including them is a stylistic choice.
karol 14 hours ago|
I read this and classified as "future issue". If it's so easy as the author described it will happen, or it's already happening and it will be discovered much later.

The Dieselgate is a good analogy. Incentives, how easy it is to get to profit.

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