Dealing with Kindle for PC/Mac 1.19 and KFX in calibre

[darryl]

Originally Posted by pdurrant

Does the disabling KFX download still work on 1.28?

(I haven't updated from 1.17 yet, but I was considering a move to Mac OS 10.15 which would require 1.25 or later.)

No. Changing the name of renderer-test seems to do nothing on 1.28. According to the first post in this thread:

Note: This will not work with recent versions of Kindle for PC. The last PC version in which KFX can be disabled can be downloaded directly from Amazon using this link: Kindle for PC 1.24.3 (51068).
Additional steps, linked to below, are required to make this method work with recent versions of Kindle for Mac.

1.24.3 will also work with the latest tools to decrypt kfx, so you can have things both ways by changing the name of renderer-test according to your preferences.

[lkmiller]

Originally Posted by pdurrant

Does the disabling KFX download still work on 1.28?

(I haven't updated from 1.17 yet, but I was considering a move to Mac OS 10.15 which would require 1.25 or later.)

No, for PC. Yes, for Mac. There's a link under Method 2 to another post by odamizu with further instructions for later versions of K4Mac.

ETA: New installations of Kindle for Mac on Catalina should now work with the update to DeDRM. I'll be eager to hear if that is indeed true.

[jhowell]

Originally Posted by darryl

Barring a sneaky update to 1.28 it appears that an alternate DRM scheme was included in that version and possibly some of the preceding versions after 1.24.3. It may be as simple as another key hidden in the software, an alternate decryption algorithm or both. As jhowell said, on the fly changes to DRM.

Amazon seems to be relying more and more on remotely triggered features. There is the dark mode icon slowly rolling out on Kindle devices, the missing cover thumbnails for sideloaded books, and now the enabling of new KFX DRM.

Since the alternative KFX DRM has now been activated, it is only a matter of time before it too is cracked. If Amazon is really serious about KFX DRM they will likely be adding at least one more hidden DRM scheme in upcoming software releases in order to prepare for that eventuality.

[Dogbert]

I'm trying to import a kfx from my eink kindle into calibre (Windows 10) and the behavior is odd. I have both the kfx, Kindle Previewer app, and dedrm plugin installed.

With my device attached if I navigate within Calibre to Device and click on the book in question it gives me a locked with DRM message. If I navigate in Windows to the file in question and double click it Calibre processes it and puts it into a folder named "Unknown" on the Device (Kindle) and this file (kfx) is then able to be opened by the Calibre viewer. Within Calibre if I right click on this file though and try to send it to my Library it gives me the error that:

"The following books are in KFX format. KFX is a virtual book format, and cannot be transferred from the device ............... ".

So if I want to get this book into my Calibre Library in an azw3 (or epub) format how do I go about doing it, because if seems like if the Calibre viewer can open it that I should be able to add it to my Library. Thanks.

[odamizu]

nevermind

[ben_r_]

Awesome thread! Was able to get Method 1 from the OP working. Took a bit to find a legit copy of 1.17 that had a matching hash, but eventually found one for Windows. Was able to use DeDRM 6.8.0 with no issues on a brand new Amazon book. Been years since I'd tried this so it was nice to see it's still possible!

[jhowell]

Originally Posted by Dogbert

I'm trying to import a kfx from my eink kindle into calibre (Windows 10) and the behavior is odd.

I am having trouble following what you are doing but I don’t think it matters. I recommend downloading books from Amazon’s website instead of trying to access them from your Kindle. See method 3 in the first post of this thread.

[apprenticesakuya]

So here's what's going on:

With K4PC 1.25, Amazon introduced a slight variation on the KFX DRM scheme with VoucherEnvelope versions 2 and 3, which add an additional step before the book key is decrypted. The DRM vouchers seem to randomly use either one of those, and these are what the code I pushed supports.

With K4PC 1.27, they also added versions 4 all the way up to 28. Up until yesterday, books downloaded with K4PC 1.27+ still used either v2 or v3, but now they've started using v4.

None of the higher versions do anything new or interesting, they're all pretty much the same thing as v2 and v3, so I'm not sure why they even exist in the first place.

Also, can someone test if books that previously required 1.26+, e.g. textbooks, can still be downloaded and read on 1.26? The store pages say so at least, but there would be no point in them enabling the new DRM version if all books still work on 1.26...

As a bonus, here's a way to disable KFX downloads on K4PC/Mac 1.28. Since preventing it from running the renderer test now just results in KFX being enabled (and you can't simply modify that binary since there's an integrity check), the best way I've found is to patch the Kindle binary itself to make it think the test failed:

PowerShell script for Windows:

$file = [IO.File]::Open([Environment]::GetEnvironmentVariable("LocalAppData") + "\Amazon\Kindle\application\Kindle.exe", [IO.FileMode]::Open); $file.Seek(0xD5325B, [IO.SeekOrigin]::Begin); $file.WriteByte(0x6A); $file.WriteByte(0x01); $file.WriteByte(0x90); $file.Close()

Bash script for Mac:

printf '\x41\xbc\x01' | dd of=/Applications/Kindle.app/Contents/MacOS/Kindle bs=1 seek=2695614 count=3 conv=notrunc && printf '\x90\x90\x90\x90\x90\x90' | dd of=/Applications/Kindle.app/Contents/MacOS/Kindle bs=1 seek=3217385 count=6 conv=notrunc

Note that these patches require the renderer-test binary to run normally, so make sure it's untouched.

[darryl]

Apprentice Sakuya. Thank you for all your hard work and your above comments. Versions up to 28 sound ominous, if only for future implications. Unfortunately I don't have any of the books requiring 1.26+. so far as I'm aware, nor any easy way of locating them. Testing will indeed be interesting.

[darryl]

I'd appreciate it if someone can provide a download link to a clean version of K4PC 1.26, or even a checksum of the legitimate version. I'll keep looking but my attempts so far have only yielded infected files.

[odamizu]

Originally Posted by apprenticesakuya

Bash script for Mac:

printf '\x41\xbc\x01' | dd of=/Applications/Kindle.app/Contents/MacOS/Kindle bs=1 seek=2695614 count=3 conv=notrunc && printf '\x90\x90\x90\x90\x90\x90' | dd of=/Applications/Kindle.app/Contents/MacOS/Kindle bs=1 seek=3217385 count=6 conv=notrunc

Intriguing. For those of us who don't know what we're doing, is this as simple as opening a Terminal window, copying and pasting the above script, then hitting return? And does this only need to be done once?

Thank you!

... Also, can someone test if books that previously required 1.26+, e.g. textbooks, can still be downloaded and read on 1.26? ...

Wish I could help test, but I don't have any textbooks or fancy books that require 1.26+, either.

[apprenticesakuya]

Originally Posted by darryl

I'd appreciate it if someone can provide a download link to a clean version of K4PC 1.26, or even a checksum of the legitimate version. I'll keep looking but my attempts so far have only yielded infected files.

https://s3.amazonaws.com/kindleforpc...1.26.55076.exe

Originally Posted by odamizu

Intriguing. For those of us who don't know what we're doing, is this as simple as opening a Terminal window, copying and pasting the above script, then hitting return? And does this only need to be done once?

Yes and yes. Make sure you're on 1.28, as that's the only version this specific patch will work on.

[darryl]

Originally Posted by apprenticesakuya

https://s3.amazonaws.com/kindleforpc...1.26.55076.exe

Thanks!

[odamizu]

Originally Posted by apprenticesakuya

Yes and yes. Make sure you're on 1.28, as that's the only version this specific patch will work on.

[darryl]

Okay. I've now installed K4PC 1.26 and, as expected, it is decrypting and adding kfx books as kfx with the latest tools. If I can find an ebook that requires 1,26 and above which is free or at least doesn't cost an arm and a leg I will give it a try.