Social DRM on decrypted KFX?

[cloudbug]

Do decrypted KFX ebooks have watermarks of any kind? I know AZW3 had one, which could be deleted by clicking an option in DeDRM. Is this still the case? I ask because there's random text in the .xhtml files on the converted EPUB, for example. It reads fine, though.

[DNSB]

Do you have an example of the random text? As near as I can tell in a quick and dirty test with 4 decrypted KFX files downloaded from 2 Amazon accounts (download using the Amazon Microsoft Kindle app and decrypted with Sats' tool), there are no differences in the text files.

[cloudbug]

Originally Posted by DNSB

Do you have an example of the random text? As near as I can tell in a quick and dirty test with 4 decrypted KFX files downloaded from 2 Amazon accounts (download using the Amazon Microsoft Kindle app and decrypted with Sats' tool), there are no differences in the text files.

The first .xhtml file is called Iifn8Nc-S0W3SA89oHVLoA*-right.xhtml, and the others are called similarly with some changes in the number (*).

I'm also wondering if, if not the text, maybe the images are watermarked?

[JSWolf]

Amazon puts a watermark in the OPF file. At least they did with KF8.

[cloudbug]

Originally Posted by JSWolf

Amazon puts a watermark in the OPF file. At least they did with KF8.

Right, I remember that. What's the state of watermarking on Kindle books and comics since then, though?

[jhowell]

Books delivered by Amazon to a Kindle device or app contain a "watermark" metadata field that identifies the Amazon account for which the book was downloaded among other things.

In MOBI and KF8 (azw3) formats the watermark is stored in field number 208 of the EXTH header. KindleUnpack includes this as a comment in the OPF file it creates when converting to EPUB.

In KFX format that field is contained in a separate voucher file. That file contains all of the user-specific information about the book as well as the DRM encryption keys needed to decrypt it. The rest of the files that make up a KFX book are identical across users.

A .kfx-zip archive typically contains all of the files associated with a KFX format book, including the voucher with the watermark. A .kfx file from which DRM has been removed does not contain anything from the voucher and so does not have any personally identifiable information.

[cloudbug]

Originally Posted by jhowell

Books delivered by Amazon to a Kindle device or app contain a "watermark" metadata field that identifies the Amazon account for which the book was downloaded among other things.

In MOBI and KF8 (azw3) formats the watermark is stored in field number 208 of the EXTH header. KindleUnpack includes this as a comment in the OPF file it creates when converting to EPUB.

In KFX format that field is contained in a separate voucher file. That file contains all of the user-specific information about the book as well as the DRM encryption keys needed to decrypt it. The rest of the files that make up a KFX book are identical across users.

A .kfx-zip archive typically contains all of the files associated with a KFX format book, including the voucher with the watermark. A .kfx file from which DRM has been removed does not contain anything from the voucher and so does not have any personally identifiable information.

Not even images? That's good to know, thank you.

[axu2]

Originally Posted by cloudbug

Right, I remember that. What's the state of watermarking on Kindle books and comics since then, though?

For manga, sometimes I see weird lines on pages that just look out of place.

I compared them to the humble bundle release and the lines weren't there, IDK maybe it was a watermark.