Kindle Watermarking format

sasq · 02-08-2012, 09:52 AM

So I just explored the watermark tag found in AZW files a bit, and this is what I found so far;

The tag has the format

atv:kin:1:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX=:YYYYYYYYYYYYYYYYY YYYYYYYYYY=

where X and Y are base64 encoded numbers, the first 1024bit long and the second 160bit.

X has the following components

16 bytes Unknown
48 bytes Book ID (ie same for all copies of this book)
32 bytes User ID (ie same for all books downloaded to this user/device)
32 bytes Unknown

I have not compared different devices yet, that may change things.

Anyone found out anything else?

-- Sasq

Serpentine · 02-08-2012, 05:23 PM

First 16 might be an MD5, I imagine the last block will be some sort of hash reference to download logs stored server side. Shouldn't be an actual device ID in there tho.

Dylan Tomorrow · 12-03-2012, 10:05 AM

FYI, I just noticed that on my Kindle Touch this watermark is stored in the SQLITE Collections Database at /var/local/cc.db in column p_watermark in table entries not just for DRMed books (p_isDRMProtected=1) but for one purchased book where I removed the DRM as well (p_isDRMProtected=0).

When I unpack said book with MobiUnpack the same watermark shows up in the BookName/mobi7/BookName.opf as

Code:

<meta name="Watermark" content="[...]" />

and is reported as an EXTH header when unpacking.

The cc.db also lists such a watermark for one mobi that I let Readability.com email to my Kindle. Strange ...

zxczxc · 03-23-2016, 09:15 PM

Just to add a little more information, maybe not new:
I downloaded the same book via K4PC and from Big A's website to sideload - I wanted to see if there were any differences. After DRM removal, the .awz3 files still had different hashes.
I used KindleUnpack and used a tool to diff the folders, all that was different were 2 lines in the content.opf in the OEBPS folder.

I see <meta property="dcterms:modified">2016-03-24T00:39:51Z</meta>
and then a 422 hex character long watermark.
<meta name="Watermark (hex)" content="XYZ" />

For me, the books share the same first 20 characters of the watermark.
Also, further in the watermark, there is a shared 169 characters.

02-08-2012, 09:52 AM	#1
sasq Junior Member Posts: 1 Karma: 2952 Join Date: Jan 2012 Device: Kindle	Kindle Watermarking format So I just explored the watermark tag found in AZW files a bit, and this is what I found so far; The tag has the format atv:kin:1:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX=:YYYYYYYYYYYYYYYYY YYYYYYYYYY= where X and Y are base64 encoded numbers, the first 1024bit long and the second 160bit. X has the following components 16 bytes Unknown 48 bytes Book ID (ie same for all copies of this book) 32 bytes User ID (ie same for all books downloaded to this user/device) 32 bytes Unknown I have not compared different devices yet, that may change things. Anyone found out anything else? -- Sasq

12-03-2012, 10:05 AM	#3
Dylan Tomorrow Connoisseur Posts: 62 Karma: 640495 Join Date: Jul 2012 Location: Germany Device: Kindle Touch, Android smartphone w/ FBReader	FYI, I just noticed that on my Kindle Touch this watermark is stored in the SQLITE Collections Database at /var/local/cc.db in column p_watermark in table entries not just for DRMed books (p_isDRMProtected=1) but for one purchased book where I removed the DRM as well (p_isDRMProtected=0). When I unpack said book with MobiUnpack the same watermark shows up in the BookName/mobi7/BookName.opf as Code: <meta name="Watermark" content="[...]" /> and is reported as an EXTH header when unpacking. The cc.db also lists such a watermark for one mobi that I let Readability.com email to my Kindle. Strange ...

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02-08-2012, 05:23 PM	#2
Serpentine Evangelist Posts: 416 Karma: 1045911 Join Date: Sep 2011 Location: Cape Town, South Africa Device: Kindle 3	First 16 might be an MD5, I imagine the last block will be some sort of hash reference to download logs stored server side. Shouldn't be an actual device ID in there tho.

03-23-2016, 09:15 PM	#4
zxczxc Addict Posts: 229 Karma: 136002 Join Date: Apr 2013 Device: PW	Just to add a little more information, maybe not new: I downloaded the same book via K4PC and from Big A's website to sideload - I wanted to see if there were any differences. After DRM removal, the .awz3 files still had different hashes. I used KindleUnpack and used a tool to diff the folders, all that was different were 2 lines in the content.opf in the OEBPS folder. I see <meta property="dcterms:modified">2016-03-24T00:39:51Z</meta> and then a 422 hex character long watermark. <meta name="Watermark (hex)" content="XYZ" /> For me, the books share the same first 20 characters of the watermark. Also, further in the watermark, there is a shared 169 characters.