|02-08-2012, 10:52 AM||#1|
Join Date: Jan 2012
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?
|02-08-2012, 06:23 PM||#2|
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.
|12-03-2012, 11:05 AM||#3|
Join Date: Jul 2012
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
<meta name="Watermark" content="[...]" />
The cc.db also lists such a watermark for one mobi that I let Readability.com email to my Kindle. Strange ...
|03-23-2016, 10:15 PM||#4|
Join Date: Apr 2013
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.
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