Unable to decrypt non-Mobi Kindle Default Dictionaries

[mallomar]

Question / bug report

Hi,

I am bringing my Kindle dictionaries from my e-ink Kindle to KoReader on my Onyx Boox, stripping the DRM with this plugin, unpacking with Kindle Unpack and the converting with mobi2stardict. I read in several languages and was able to strip the DRM from fifteen dictionaries in MOBI format, unpack them and then convert them to StarDict, but two others, which show up in AZW and KFX formats, respectively, did not have their DRM stripped. I pulled them all from the same Kindle, so it's not an issue of the serial number being off. It seems like a bug, unless there's something else I need to tweak.

Which version of Calibre are you running?

7.2.4

Which version of the DeDRM plugin are you running?

v10.0.3

If applicable, which version of the Kindle software are you running?

5.16.2.1.1

Log output

Paste log output here.

[ElleKayEm]

If they are the dictionaries that came installed on the Kindle, from what I understand they do not decrypt with the serial number based key that unlocks your own books. Their key is unknown.

If they're purchased books, try updating to DeDRM 10.0.9 and installing the KFX Input plugin.

[mallomar]

Thanks, @ElleKayEm. Fourteen of the fifteen dictionaries I decrypted are ones that come for free so that doesn't explain it. After what you said, though, I tried downloading one of the other two directly from Amazon and decrypting it worked, so I guess it's apparently encrypted differently than the file that came on the Kindle itself. The other dictionary I was trying to decrypt is a KFX file and Amazon does not give the option for download and transfer. So I guess these free dictionaries below that are in KFX cannot be decrypted?

It appears to be all of the free ones they added in 2018 which cannot be downloaded and transferred. All of the ones I've had since 2016 work. So it seems like they changed the format and encryption in 2018.

[ElleKayEm]

Sorry, when I referred to "purchased", I also meant books you've "bought" for free. When you tried the KFX book did you have DeDRM 10.0.9 and the KFX Input plugin installed? You also need to leave KFX format in its original folder structure when adding to calibre.

[mallomar]

@ElleKayEm Thanks. I have KFX Input plugin installed. I'll try it with the 10.0.9 build of DeDRM. I don't see an option in KFX Input or under KFX in Import Options regarding the folder structure. Could you tell me where that would be?

[j-howell]

Dictionaries in KFX format are structured in a way that DeDRM does not support. There is currently no way to process those.

[ElleKayEm]

Well, fyi for non-dictionary kfx: I mean when you are adding a book to calibre the main book file needs to be left with its related files so the KFX Input plugin can find them.