Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Extracting content from an LCP “protected” ePub

shkspr.mobi

Post reply on HN
Print view View original

21–30 of 72 posts

Re: Extracting content from an LCP “protected” ePub

#21

Post by miki123211 »

baruchel wrote: post #12

A more straightforward way to do it, IMHO, is to use Thorium in conjunction with a Python script called lcpdedrm. If I remember well, that script isn't available directly any longer, but it is easy to look around and find copies of it. Then use Thorium for locally saving the file and use the Python script for removing the DRM.

Why do you even need Thorium for this?

If the files are just AES-encrypted and the links are there, as the linked article suggest, it seems that it would be easy to create a standalone script to download and decrypt these.

Re: Extracting content from an LCP “protected” ePub

#22

Post by edent »

baruchel wrote: post #12

A more straightforward way to do it, IMHO, is to use Thorium in conjunction with a Python script called lcpdedrm. If I remember well, that script isn't available directly any longer, but it is easy to look around and find copies of it. Then use Thorium for locally saving the file and use the Python script for removing the DRM.

The lcpdedrm script is, if I remember correctly, only suitable for Profile 1.0, which has since been replaced with the newer 2.0 version.

Re: Extracting content from an LCP “protected” ePub

#23

Post by edent »

miki123211 wrote: post #21
baruchel wrote: post #12

A more straightforward way to do it, IMHO, is to use Thorium in conjunction with a Python script called lcpdedrm. If I remember well, that script isn't available directly any longer, but it is easy to look around and find copies of it. Then use Thorium for locally saving the file and use the Python script for removing the DRM.

Why do you even need Thorium for this? If the files are just AES-encrypted and the links are there, as the linked article suggest, it seems that it would be easy to create a standalone script to download and decrypt these.

(OP here) I discussed how the DRM works in an earlier blog post - https://shkspr.mobi/blog/2025/03/some-thoughts-on-lcp-ebook-...

Essentially, the key for decrypting the files is made up of the book owner's passphrase and the super-secret key embedded in the closed-source binary.

I wasn't able to reverse engineer the binary or extract that key.

Re: Extracting content from an LCP “protected” ePub

#25

Post by joecool1029 »

damnitbuilds wrote: post #19
captn3m0 wrote: post #9

Readium was also responsible for the takedown on the noDRM repo, a few years ago: https://news.ycombinator.com/item?id=29870151 The repo came back, but without the readium DRM code: https://github.com/noDRM/DeDRM_tools/blob/master/DeDRM_plugi...

To further Streisand this, I think the restored repo is here: https://repo.or.cz/DeDRM_tools-LCP.git

It works. Though I've found it only works for LCP epubs, not pdf's.

Re: Extracting content from an LCP “protected” ePub

#26

Post by Finnucane »

lxgr wrote: post #15
damnitbuilds wrote: post #14

One should also note that Thorium is a remarkably crappy app to read Epubs on.

I've never used it myself, but I'd be really surprised if it somehow managed to be worse than Adobe Digital Editions.

Well, it does have the advantage of being actively maintained. If not necessarily very well. Recently, I had the fun of noting that their app was no longer behaving correctly with endnote links, and they suggested that my links were coded wrong. I pointed out that they were not, were standards-compliant and worked fine in every other epub reader I had. Even ADE! So I don't know what they were trying to do.

Re: Extracting content from an LCP “protected” ePub

#28

Post by op00to »

The only time to directly threaten legal action is when you don't think legal action will achieve your goal, and you've got nothing else. Otherwise, there is no benefit to threatening legal action. Sure, you can imply it, but you gain nothing by showing those cards.

Re: Extracting content from an LCP “protected” ePub

#29

Post by kristo »

ferbivore wrote: post #2

> You can, for sure, publish information relative to your discoveries to the extent UK laws allow. After study, we'll do our best to make the technology more robust. If your discourse represents a circumvention of this technical protection measure, we'll command a take-down as a standard procedure. Disgusting behaviour, as expected from the publishing industry I suppose. This "EDRLab" outfit appears to be little more…

They make a software to help libraries lend ebooks for free. Without their DRM you either wouldn’t be able to borrow ebooks because publishers would never agree to it, or would be limited to kindle/libby to read them. They’re not perfect but how is it bad behavior to say you’ll issue a takedown notice if your copyright material is republished? I don’t really understand why they’re being treated as the enemy here?

Re: Extracting content from an LCP “protected” ePub

#30

Post by NoMoreNicksLeft »

op00to wrote: post #28

The only time to directly threaten legal action is when you don't think legal action will achieve your goal, and you've got nothing else. Otherwise, there is no benefit to threatening legal action. Sure, you can imply it, but you gain nothing by showing those cards.

But the goals that these people pursue are difficult to understand or anticipate. You assume that because these people are employed by some business entity that their goals are "make more money" and such. That's rarely the case, even if we allow for the unenlightened version of "make more money".

Instead, assume that many, possibly even most, are more interested in being punitive out of some warped sense of justice. Though it might cost them a million in legal fees to discourage efforts to fix their DRM which in turn might only preserve a few tens of thousands in sales or other earning potential, they still doggedly chase these "goals". Sometimes, I think, the lawyers even point this out, only to be overruled by top management. This means that legal action can almost always achieve the goal, being that the goal is nothing more than to make their targets miserable.

Post reply on HN