OK, what's Kobo SDRM?

[Daniel Jackson]

Originally Posted by Cactus Chef

Assuming SDRM is just a watermark and the file itself is ultimately in plaintext, shouldn't it be trivial to remove any member info from the downloaded book metadata?

This is a forum of enthusiasts, after all, who regularly brag about editing every book they buy to standardize the book's stylesheets and hyphenation.

There are ways to hide watermarks. Some minor changes in the html/css code that do not affect the content appearance of the rendered book. Perhaps some identifying pixels in the cover or other images. Each sold book has its own unique set of small randomized changes. Very easy for the seller to analyze and catch the leaker.

[DNSB]

Originally Posted by John F

I would assume social DRM isn't just limited to metadata?

From the samples I've seen, it can be as simple as having your email address or other identifier in multiple places in the file, having spaces/double spaces used to encode the information throughout the file, using steganography to hide information in the cover or other images, adding a file into the META-INF folder that contained encrypted user information or adding a line into the .opf file with the scrambled user information.

[Cactus Chef]

Originally Posted by DNSB

From the samples I've seen, it can be as simple as having your email address or other identifier in multiple places in the file, having spaces/double spaces used to encode the information throughout the file, using steganography to hide information in the cover or other images, adding a file into the META-INF folder that contained encrypted user information or adding a line into the .opf file with the scrambled user information.

Seems like it should be pretty easy to just have two people independently purchase an SDRM book (or even just one person with two accounts) and then diff the contents of the two EPUB directories to figure out where all the potential watermarks might be.

[DNSB]

Originally Posted by Cactus Chef

Seems like it should be pretty easy to just have two people independently purchase an SDRM book (or even just one person with two accounts) and then diff the contents of the two EPUB directories to figure out where all the potential watermarks might be.

That's what I did when I was looking at SDRM. Two accounts and purchased the same book from each. The sheer variety of techniques was the real surprise in the limited samples I had to look at.

[Aleron Ives]

Do we have any idea what prompts Kobo to offer this? Does the publisher get to decide, the same way some publishers allow their books to be sold without DRM? So far I've yet to buy a book that gave me the SDRM option.

[DNSB]

I'm not sure what book the OP was referring to. I did a search on Kobo US for books with Rowling and none of the ones priced at $2.99 US had an SDRM option.

[JSWolf]

Originally Posted by DNSB

From the samples I've seen, it can be as simple as having your email address or other identifier in multiple places in the file, having spaces/double spaces used to encode the information throughout the file, using steganography to hide information in the cover or other images, adding a file into the META-INF folder that contained encrypted user information or adding a line into the .opf file with the scrambled user information.

Would any metadata in the images be removed if I did a lossless compression in the calibre editor?

[graycyn]

Originally Posted by issybird

Bingo. Readium will be a game-changer and especially those who deDRM all their purchases should enthusiastically switch to SDRM when possible. Help make it look like a viable alternative.

I'm trying to imagine a scenario where my computer gets hacked and it's worth the hacker's while to upload my library to the darknet. Something can be theoretically possible but not be worth considering, certainly not if it cuts off more worthwhile actions.

Exactly. It's one of those kind of minor worries, rather than a major one. I can't be bothered to dwell on the minor stuff.

One, been using a computer since the Radio Shack Tandy-1000. Never had a virus, never been hacked. Using e-readers, multiple e-readers, since 2010. Never lost one, never cracked a screen.

I'm all for social DRM, and half the reason I plan to redownload that ebook is to just "show up" as a downloader, in case the powers that be are looking to see what form folks download in. I figure Adobe DRM is likely to go the way of the dodo.

[JSWolf]

Originally Posted by graycyn

Exactly. It's one of those kind of minor worries, rather than a major one. I can't be bothered to dwell on the minor stuff.

One, been using a computer since the Radio Shack Tandy-1000. Never had a virus, never been hacked. Using e-readers, multiple e-readers, since 2010. Never lost one, never cracked a screen.

I'm all for social DRM, and half the reason I plan to redownload that ebook is to just "show up" as a downloader, in case the powers that be are looking to see what form folks download in. I figure Adobe DRM is likely to go the way of the dodo.

Can you do us a favor? Remove the DRM from the ePub with DRM. Put both versions of the ePub in calibre. Do a comparison using the calibre editor and let us know how bad or not the social DRM is. Thanks.

[graycyn]

Originally Posted by DNSB

I'm not sure what book the OP was referring to. I did a search on Kobo US for books with Rowling and none of the ones priced at $2.99 US had an SDRM option.

From the Wizarding Archive by J.K. Rowling

I went just now to download the SDRM version, and the option was still there.

[graycyn]

Originally Posted by JSWolf

Can you do us a favor? Remove the DRM from the ePub with DRM. Put both versions of the ePub in calibre. Do a comparison using the calibre editor and let us know how bad or not the social DRM is. Thanks.

Well, I'm not a power Calibre user, so I'm not quite sure exactly how to do a comparison, but I'll see if I can. I wouldn't necessarily know what to look for, honestly. Social DRM can be done in varied ways, some obvious, some not so much.

EDIT: Just took a quick look at the size of the downloaded Adobe DRM file prior to deDRM, i.e. as it sits in my Digital Editions folder ... and there's a fair file-size difference!

Adobe DRM epub = 2,028 KB
Kobo SDRM epub = 3,435 KB

OK, have the SDRM book open in Calibre Viewer, I'm not seeing any pages with my name on it though I don't have time to scroll through the whole thing.

At the bottom of the copyright page, there is this:

The license to this eBook belongs to you. This eBook can be read on Mac or PC computers, eReaders, tablets, and mobile phones.

(Re)selling, distributing, (sub)licensing, renting, leasing or otherwise assigning or transferring any rights in or to the license or this eBook, or reproducing, publishing, broadcasting or making this eBook or any portion of it available to any third party otherwise is strictly prohibited.

This eBook is watermarked with traceable information that identifies you as the owner of the license, as a security measure in the event of misuse.

Enjoy your eBook!

[DNSB]

Originally Posted by graycyn

From the Wizarding Archive by J.K. Rowling

I went just now to download the SDRM version, and the option was still there.

My error. I was looking for that in the book information. Oddly, I picked up that book a while back so checked and the SDRM download option shows when I select download.

[Cactus Chef]

Originally Posted by graycyn

Well, I'm not a power Calibre user, so I'm not quite sure exactly how to do a comparison, but I'll see if I can. I wouldn't necessarily know what to look for, honestly. Social DRM can be done in varied ways, some obvious, some not so much.

EDIT: Just took a quick look at the size of the downloaded Adobe DRM file prior to deDRM, i.e. as it sits in my Digital Editions folder ... and there's a fair file-size difference!

Adobe DRM epub = 2,028 KB
Kobo SDRM epub = 3,435 KB

That seems like way too much to be just watermarks. Maybe different image resolutions/compression algorithms being used?

I'd be happy to contribute to the research effort if we could find a target book that wasn't Rowling...

[graycyn]

Originally Posted by Cactus Chef

That seems like way too much to be just watermarks. Maybe different image resolutions/compression algorithms being used?

I'd be happy to contribute to the research effort if we could find a target book that wasn't Rowling...

My first effort at compare was a bust, because I'd forgotten that I'd already assigned tags and such to the Adobe DRM book. So, I imported the Adobe DRM book into Calibre again, then exported to a folder without doing anything, other than letting Calibre remove DRM.

Selected the SDRM book, went to compare, and there seem to be various differences. I'm a little confused, because I'm not sure what I'm doing or even which book is which in the compare panel now, (LOL!), but, there are, from quick observation, uuid differences, image size differences, and differences in the spans for the page-map IDs, in terms of the order the info contained within appears.

So it seems multiple sorts of changes going on. I'll let someone else go for the definitive statement on what might be different and whether it's removeable. Since I've no intentions to share such books with anyone other than my husband, I'm for social DRM if Adobe DRM should bite the dust.

Right panel:

<span id="page-5" role="doc-pagebreak" epub:type="pagebreak" aria-label=" Page 5. "/>

Left panel:

<span aria-label=" Page 5. " epub:type="pagebreak" id="page-5" role="doc-pagebreak"/>

There ya go...

[graycyn]

Originally Posted by Cactus Chef

That seems like way too much to be just watermarks. Maybe different image resolutions/compression algorithms being used?

I'd be happy to contribute to the research effort if we could find a target book that wasn't Rowling...

After import into calibre, the filesize column shows 1.8 MB for the SDRM book and 2MB for the Adobe DRM/deDRM import.

Anyway, I definitely think different image stuff is going on, but not change in resolution, those seem the same, it's just image filesize changes, and slight ones.