Downloading a .epub from a .acsm

Question

I want to transfer books I buy on Google Play (downloads a .acsm) to my Kobo reader device. Everything I can find on internet about it:

• has you running Adobe Digital Editions
• aims at removing the DRM

I want to avoid both: I'm fine with the DRM as long as I can read the book on my device, and I don't want to run ADE through wine or otherwise (already lost hours trying that).

I guess acsm -> epub "conversion" is mostly a download, but are there conversions/encryptions along the way ? There is an url in the <src> tag in the .acsm, but also a lot of other parameters. Is there a way to download "manually" (without ADE) ?

Solution 1

I created a program called Knock to convert ACSM files to DRM-free EPUB files at the command line:

[user@computer:~]$ knock ./example.acsm
downloading the file from Adobe...
removing DRM from the file...
DRM-free EPUB file generated at ./example.epub

Although you say you are fine with DRM, this removes it, which shouldn't be an issue for you as your reader should be able to read the plaintext EPUB file just fine.

It doesn't use Adobe Digital Editions and it doesn't use Wine. It is completely free and open-source software for native Linux.

Solution 2

I see this is an old question... but perhaps this even older blog post at ebookreadersoftware.wordpress.com will answer it:

ACSM Files Explanation

Blog Post says:

Any website that sells ebooks in Adobe’s DRM-protected format will tell you ahead of time that you must use Adobe Digital Editions. If you skip over all those instructions, and you don’t install the software you are told that you need, then of course your computer won’t know what to do with this .acsm file.

As I mentioned above, the .acsm file is NOT supposed to contain the entire text of a book. It is not the ebook at all. It is a small file that manages the download of the ebook through Adobe’s content server.

Comments

[Gnurfos]

Thanks but it doesn't really help. It keeps on repeating again and again that the acsm does not contain the book, which I was already aware of, as my question hopefully shows. And keeps advertising for ADE, which I don't want to/cannot run.

[RubberStamp]

Perhaps it's a little easier to think of the acsm file as a crypto key and the ADE as the program which reads the key.

[Gnurfos]

If one was searching for an explanation, I think here is the best one: "a per-user RSA key encrypts a per-book AES key which encrypts the content". Now I'm in need of something to download the encrypted content without using ADE.

[RubberStamp]

>download the encrypted content without using ADE... As far as I understand, there is no way to do this. The ADE program is required to verify the keys. This is, of course frustrating for those of us who prefer not to use proprietary Windows only software. However, the world doesn't seem to always care about ethics.

[Gnurfos]

Thank you for that. I don't have time to try it seriously at the moment but I see it uses a program called "activate" . What is that ?

[BentonEdmondson]

@Gnurfos libgourou-utils provides activate and acsmdownloader to get the EPUB from Adobe and inept-epub provides inept-epub for decrypting the EPUB. See their readmes for more details

[axel22]

Great program, thanks.