ADE alternative for Linux

[ReadOnLinux]

The mentioned book can only be downloaded next month so I took the previous version and got the same result:

$ ./utils/acsmdownloader -f ~/Downloads/URLLink.acsm -o x.pdf
Exception code : 0x5007
Message : Invalid zip file x.pdf

I downloaded the pdf book using ADE and did a "diff -a" between both files.
As I dont know, which private information are coded in the URLlink.acsm file I send it via a PM as well as the diff information.

The libgourou version I use is:

$ egrep "VERSION.*[0-9.]+.*" include/*.h
include/libgourou.h:#define HOBBES_DEFAULT_VERSION "10.0.4"
include/libgourou.h:#define LIBGOUROU_VERSION "0.4.2"
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.3 LTS
Release: 20.04
Codename: focal
$ uname -r
5.4.0-90-generic

[soutade]

Fixed in v0.4.3. Thanks for your report

[edent]

Here's one which doesn't work. https://archive.org/details/informationwarfa00denn
I logged in to the Internet Archive, borrowed the book for 14 days, ran acsmdownloader v0.4.4

The process took ages and didn't show any errors, when I tried to open the PDF, my reader asked me for a password.

The problem seems to occur with any PDF from https://archive.org/details/books?and[]=year%3A%222015%22&and[]=lending___status%3A%22available_to_borrow%22 - although the ePubs work fine.

Thanks for the incredibly helpful tool!

[ReadOnLinux]

If you download with acsmdownloader the pdf is DRM encrypted. If you try to open this file with a pdf-reader you will be asked for a password.
Have you tried to open the downloaded pdf file with a Adobe-DRM enabled pdf-Reader?

[edent]

Originally Posted by ReadOnLinux

If you download with acsmdownloader the pdf is DRM encrypted. If you try to open this file with a pdf-reader you will be asked for a password.
Have you tried to open the downloaded pdf file with a Adobe-DRM enabled pdf-Reader?

I couldn't find a DRM enabled reader for Linux. I tried on my ebook and Android - and they both showed an error.
Are you able to download PDFs from the Internet Archive?

[ReadOnLinux]

Sorry, I have a Tolino epos SW-Version 15.2.0 that has been registered to Adobe DRM. As I normally use this tablet offline, I copy the downloaded pdf file into directory "Books", when the Tolino is connected via USB to my Linux Notebook. After disconnecting the USB port, the Tolino finds the new loaded books and the pdf file can be read.

I did not made an intensive google search for DRM enabled PDF readers on Linux. But I know that there is the possibility to run Adobe ADE (a Windows Program) under Linux using wine. I've heard about the possibility to use Calibre but have no experience/knowledge about that.

[soutade]

Hello all,

I released a new version (v0.5) that (mainly) supports anonymous accounts and add a DRM removal utility. Hope you'll enjoy it ! All is available at http://indefero.soutade.fr/p/libgourou/

[Leseratte_10]

I haven't tested it yet, but looking at the code this seems to have the same bug as https://github.com/apprenticeharper/...ls/issues/1828 :

When parsing the encryption.xml, you need to manually check for each entry if that's related to AdobeDRM or if that's something else (like font data). And after decryption, you should only delete the AdobeDRM entries from the encryption.xml, and only delete the whole file from the EPUB if it's empty (no other entries that aren't DRM).

Otherwise this breaks embedded obfuscated fonts (which are also included in the encryption.xml).

[soutade]

Thanks Leseratte. I was not aware about that kind of encryption. I'll update my code to check encryption algorithm value.

[ben4ever]

Originally Posted by soutade

add a DRM removal utility

It seems that the adept_remove utility is not included in the downloadable archive. Could you please add it?

[soutade]

Oups... Fixed in v0.5.1.

[geca]

Grégory, first of thanks for libgourou.

I tried using removal util on a book I bought from an ADB-backed store provided by vendor called "inkBOOK" (Arta Tech) but unfortunately without success.

I used XML files found inside .adobe-digital-editions and the encrypted epub that got stored by the app inside Books dir of my Android phone.

The removal util exited with Segmentation fault so I decided to investigate further by looking at your code and trying to mimic the process with OpenSSL CLI.

I base64-decoded the privateLicenseKey from activation.xml and verified it was in fact a valid RSA private key:

> openssl asn1parse -inform DER -in private-license-key.bin 
    0:d=0  hl=4 l= 630 cons: SEQUENCE          
    4:d=1  hl=2 l=   1 prim: INTEGER           :00
    7:d=1  hl=2 l=  13 cons: SEQUENCE          
    9:d=2  hl=2 l=   9 prim: OBJECT            :rsaEncryption
   20:d=2  hl=2 l=   0 prim: NULL              
   22:d=1  hl=4 l= 608 prim: OCTET STRING 	   [HEX DUMP]: ...

However, when I tried decrypting encryptedKey (from rights.xml inside the epub) with it, I get the following error:

> openssl rsautl -decrypt -in rightsEncryptedKey.bin -out plain.txt-inkey private-lincense-key.pem -raw
RSA operation error
140109553796480:error:0406506C:rsa routines:rsa_ossl_private_decrypt:data greater than mod len:crypto/rsa/rsa_ossl.c:400:

1. I made sure encryptedKey was decoded from base64
2. libgourou uses RSA_NO_PADDING when decrypting, so I used -raw switch. I tried other paddings also but without success.

Since nothing worked for me, I decided to look at DeDRM decrpytion procedure, specifically decryptBook method inside ineptepub.py. There I found this:

if len(bookkey) != 172:
  print("{0:s} is not a secure Adobe Adept ePub.".format(os.path.basename(inpath)))
  return 1

Since my encrypted key has length of 192 chars this led me to assume the decryption failure was related to the difference between lengths.

Which finally brings me to my questions:
- is 172 chars also the length that libgourou implicitly assumes?
- do you have any ideas on what else I could throw at openssl to try decrypting the encryptedKey?

FYI, from what I can gather the Android app uses v12.5.2 of the librmsdk lib behind the scenes.

P.S.: You may want to introduce a new enum (CLIENT_INVALID_PKCS8) here instead of re-using CLIENT_INVALID_PKCS12:

PKCS8_PRIV_KEY_INFO* p8inf = d2i_PKCS8_PRIV_KEY_INFO_bio(mem, NULL);

if (!p8inf)
  EXCEPTION(gourou::CLIENT_INVALID_PKCS12, ERR_error_string(ERR_get_error(), NULL));

Thanks.

[soutade]

Hello,

Can you give me a stack trace of segfault ?

[geca]

Originally Posted by soutade

Hello,

Can you give me a stack trace of segfault ?

Sorry, it was acsmdownloader that caused segfault:

           PID: 101119 (acsmdownloader)
           UID: 1000 (geca)
           GID: 1000 (geca)
        Signal: 11 (SEGV)
     Timestamp: Tue 2022-02-08 18:28:22 GMT (10min ago)
  Command Line: ./utils/acsmdownloader -k /home/geca/code/adobe-drm/salt -a /home/geca/code/adobe-drm/activation.xml -d /home/geca/code/adobe-drm/device.xml -f /home/geca/code/adobe-drm/tonoc.acsm
    Executable: /home/geca/code/libgourou/utils/acsmdownloader
 Control Group: /user.slice/user-1000.slice/session-2.scope
          Unit: session-2.scope
         Slice: user-1000.slice
       Session: 2
     Owner UID: 1000 (geca)
       Boot ID: b1423d57dfb8482cad49d8174b680389
    Machine ID: 392ca35aec644e57b2fd49674fbfceed
      Hostname: oropat
       Storage: /var/lib/systemd/coredump/core.acsmdownloader.1000.b1423d57dfb8482cad49d8174b680389.101119.1644344902000000.zst (present)
     Disk Size: 408.1K
       Message: Process 101119 (acsmdownloader) of user 1000 dumped core.
                
                Module /home/geca/code/libgourou/utils/acsmdownloader with build-id 9f55955dfc2ff2fec2cc13a0fe4a6f54d145cef3
                Module /home/geca/code/libgourou/libgourou.so with build-id 792dc8daa95fe5793a92b6ed56b399de70200910
                Module linux-vdso.so.1 with build-id e4928c61148e651d67ca59cd11805e39c611af66
                Module libffi.so.8 with build-id f90d8b734f6de9b25faedb8cbfab7054dafc0a42
                Module libgpg-error.so.0 with build-id 3801187d42c4955bd93c605451430cdf1b164e63
                Module libgmp.so.10 with build-id e58d34ab389d1b649c24195c2d145e3ff2e58290
                Module libhogweed.so.6 with build-id 2d70cff7b1841b4d9ca4e8e7726cd4b944c07fdc
                Module libtasn1.so.6 with build-id ee3429ca5e94718aea4fe5249fc859e0cd88e4e9
                Module libunistring.so.2 with build-id 015ac6d6bcb60b7d8bea31a80d1941b06e8636ab
                Module libidn2.so.0 with build-id 1ce2b50ad9f9821c2c629b521cf5a3c99593d332
                Module libp11-kit.so.0 with build-id f97c44b297b54185bbe3eb6ed6dab5d8967f1532
                Module libpcre.so.1 with build-id 845483dd0acba86de9f0313102bebbaf3ce52767
                Module libicudata.so.70 with build-id e1dcc2a88cfaafed882d09c90c668af0eed4efed
                Module libgcrypt.so.20 with build-id db45f5d5e0f7af1e77324fea1885f974619ad268
                Module libcap.so.2 with build-id f56c6cd6ad4d35053340d7ff2f8f954498796739
                Module liblz4.so.1 with build-id e63600ab23b2f6997f42fac2fa56e1f02ce159a1
                Module librt.so.1 with build-id 75484da2d6f1515189eefa076e0a40328834cd16
                Module libresolv.so.2 with build-id c915c72668282861a813f7ea3c0780f37b681dc0
                Module libkeyutils.so.1 with build-id ac405ddd17be10ce538da3211415ee50c8f8df79
                Module libkrb5support.so.0 with build-id adf65240a4d2aba772d7a0772b4d015469934113
                Module libcom_err.so.2 with build-id be99503e12b86d78d6ede2f0d1ffb66408a37576
                Module libk5crypto.so.3 with build-id eb8220b8f36675aac769450be4cb6bb7f97ec38a
                Module libkrb5.so.3 with build-id 72d26767c5cb1097db75a5f5bff88860233c902b
                Module libnettle.so.8 with build-id 9a878e513c02007598fcf1e2e286c2203f13536e
                Module libgnutls.so.30 with build-id 8c87466eacaec0041a370df713d0fd200358c94c
                Module liblzma.so.5 with build-id 8b615460aa230708c5183f16bede67aa0437d95e
                Module libbz2.so.1.0 with build-id 919597c477c9b2cb9cdbb7745ed6494ac0e6da60
                Module ld-linux-x86-64.so.2 with build-id 040cc3dd10461562f177df39e3be2f3704258c3c
                Module libglib-2.0.so.0 with build-id 220436a4e27f39372710df014d2517c0387eefa4
                Module libzstd.so.1 with build-id 6214183688018e3fba6d66db10c2c8d0b45e0578
                Module libpcre2-16.so.0 with build-id 195fbccafbcff538ce13805ba687514fb614c5ed
                Module libicuuc.so.70 with build-id 2e245c2bf12f95fd8ab79b3a4be99524677cbd70
                Module libicui18n.so.70 with build-id 95af755fca990df26753a7d720b8e3ae24270e42
                Module libdouble-conversion.so.3 with build-id d162eb67b00f523a3f146b1077ae00fe04d5fb85
                Module libsystemd.so.0 with build-id 69dfd360ef432adc8911dd446411765f1922fb48
                Module libssl.so.1.1 with build-id 1024424ab33a3767da03f4fdb1fc1b02479f160f
                Module libgssapi_krb5.so.2 with build-id e6e098ad51ce7bdd3dbe902d7b0f69a90f8a9e08
                Module libdl.so.2 with build-id 5abc547e7b0949f89f3c0e21ab0c8331a7440a8a
                Module libpthread.so.0 with build-id 07c8f95b4f3251d08550217ad8a1f31066229996
                Module libc.so.6 with build-id 4b406737057708c0e4c642345a703c47a61c73dc
                Module libgcc_s.so.1 with build-id 7f8508bb914546ada778809b64b99d234337d835
                Module libm.so.6 with build-id 2b8fd1f869ecab4e0b55e92f2f151897f6818acf
                Module libstdc++.so.6 with build-id 9b5eeeb149bf3c4efe787fb398b44f00507aec87
                Module libz.so.1 with build-id 0c1459c56513efd5d53eb3868290e9afee6a6a26
                Module libzip.so.5 with build-id 68e333db519fa50980d49c7b5747320e87196bd1
                Module libcrypto.so.1.1 with build-id 4c926b672d97886b123e03a008387aecf0786de4
                Module libQt5Core.so.5 with build-id a6903ae93931b07f9214357aac2905372a406c16
                Module libQt5Network.so.5 with build-id 5d5febbf1fc5bc522602a1f1751a9931fc05b78e
                Stack trace of thread 101120:
                #0  0x00007fa6db10ac30 EVP_PKEY_get0_RSA (libcrypto.so.1.1 + 0x176c30)
                #1  0x00007fa6db10ac88 EVP_PKEY_get1_RSA (libcrypto.so.1.1 + 0x176c88)
                #2  0x0000562bcf9691f3 n/a (/home/geca/code/libgourou/utils/acsmdownloader + 0xb1f3)
                #3  0xaa1ecea45dda5716 n/a (n/a + 0x0)
                ELF object binary architecture: AMD x86-64

With adept_remove I get

Exception code : 0x5004
Message        : error:0406506C:rsa routines:rsa_ossl_private_decrypt:data greater than mod len

[Leseratte_10]

Originally Posted by geca

Since my encrypted key has length of 192 chars this ....

An encrypted book key of 192 characters means the book is encrypted with the new variant of Adobe's DRM.

In 2014 Adobe introduced a new version of their DRM because the old one is so easy to crack. It didn't gain much popularity (because, well, all eReaders would need to be updated to support it), but it looks like some vendors have recently switched to that new version.

There is no known public method to remove DRM from these books. One would need to reverse-engineer RMSDK to figure out how this new DRM works.