Do purchased DRM'ed ebooks have any personal user info stored in them?

[NonDuality]

Just wondering if ebooks with DRM bought from online stores , like Amazon, have any personally identifiable user account info stored inside them other than the DRM itself, potentially enabling the tracking of the ebook even after the DRM has been removed from it.

Thanks for any input you may have on this.

[Sirtel]

I don't think so, but I don't know for certain. Would like to know also. For example, what would happen if I lost my flash drive with the back-up copy of my Calibre library, someone found it and uploaded the books to a file-sharing site? Could the books be traced back to me?

[Xen]

12345

[DiapDealer]

I would assume that there were identifying pieces parts left. It's safer to assume so, anyway.

[Sirtel]

But we haven't heard about anyone charged with illegal uploading on that basis, have we?

[DiapDealer]

Originally Posted by Sirtel

But we haven't heard about anyone charged with illegal uploading on that basis, have we?

I haven't, no. And I wouldn't want to be the first. So assuming that some identifying metadata remains reminds me to be cautious with how/where I store my content. It's my responsibility to make sure my content doesn't wind up on somebody elses servers, devices, and thumbdrives.

[Dazrin]

Of course they do! Do you really think that all those typos in indie books are because the author didn't take the time to edit their book? No, those are there so that Amazon can track who is giving their books away by comparing which commas are out of place and which words are misspelled. They are building a database so that when the time comes (like when you have just purchased a VERY large item from them) they can delete your account and just walk away from you.

Wake up sheeple!!1!!!

Spoiler:

Seriously though, I'm not sure about Amazon or Adobe ePub DRM but I know I have seen some places that put a name and date inside the file when they sell you digital documents. Specifically I have seen it in PDFs but like DiapDealer I would assume that the others do (or at least can) add that type of data if they choose to.

[Pablo]

Originally Posted by NonDuality

Just wondering if ebooks with DRM bought from online stores , like Amazon, have any personally identifiable user account info stored inside them other than the DRM itself, potentially enabling the tracking of the ebook even after the DRM has been removed from it.

Probably. Likely places are metadata and images.

Personal information in the metadata can be removed even if it is encripted just by deleting any non-esential tags, but information disguised inside an image cannot be identified easily.

The only way to know if any account information is embedded in a book is to buy two copies of the same book, at the same time, using two different accounts, DeDRMing both and making a binary comparison of the resulting files.

[Philippe D.]

Originally Posted by Pablo

The only way to know if any account information is embedded in a book is to buy two copies of the same book, at the same time, using two different accounts, DeDRMing both and making a binary comparison of the resulting files.

(Also, make sure you use the same software to remove the DRM - binary comparison is as strict as it gets.)

Also, just because the files are different after DRM removal doesn't clearly mean there is account-identifying information in the file. There could be some additional information, but not enough to identify the account - though it's a clear sign that something is in there.

[barryem]

I don't know a lot about how ebook files are constructed but if they're not text files like simple HTML it might be possible to include identifying information in binary portions.

Once, before Audible was bought by Amazon I participated in an experiment with them. They gave a number of us in an Audible forum Audible audiobooks with identifying information and asked us to see if we could decrypt them in some way and rid the books of their watermarking. We each encrypted our book. We then exchanged decrypted copies and did whatever we thought might destroy the watermarks. I converted mine from MP3 to 2 or 3 other formats and then back to MP3. Others did similar things. Then we all returned our files to Audible and they told us exactly which file had been originally given to whom. They got it 100% right which speaks well of the durability of watermarking.

If there are binary portions, or maybe even text portions, of an ebook that a program like Calibre doesn't concern itself with, those could be where the watermark is placed. I don't know that there are such areas in an ebook file but if there are that might be the answer to the question.

Barry

[crossi]

Audible files would seem to be more complex with more places you could hide watermarks without them being detected. Converting to a straight text file, not HTML, would seem a better bet for removing watermarks. Is there anyplace in a notepad file that a watermark could be hidden without changing the text?

[Dopedangel]

If I recall correctly adobe drm does leave behind identifying information. The modify epub plugin for calibre even has an option to remove it.

[binaryhermit]

You might be able to use similar characters in non-latin character sets without being noticed... this sort of attack has been used against browsers that support IDN to enable phishing attacks. But that's technically altering the text.

[MikeB1972]

Originally Posted by crossi

Audible files would seem to be more complex with more places you could hide watermarks without them being detected. Converting to a straight text file, not HTML, would seem a better bet for removing watermarks. Is there anyplace in a notepad file that a watermark could be hidden without changing the text?

Sure, pattern of spaces at the end of paragraphs would be easiest, all sorts of ways to hide information without changing text.

I'm with DD, assume something is there and you are going to miss it.
Adept ePubs definitely have a unique id <meta content=urn:uuid: in the header of each page, not compared it across anything though so it could just be the id for the book.

[drjenkins]

Using personally identifiable watermarks is known generically as Social DRM. BooXtream is just one company that provides such a service.
https://www.booxtream.com/