read password-protected xlsx file about xlnt HOT 6 CLOSED

Hi Nai-Yuan,

There are two kinds of password protection. One encrypts the file, the other just adds an attribute to the XML. The second kind should already work since that attribute is ignored though I haven't tested it. File level encryption is more complicated, but I should be able to implement it if there's demand for it. Could you possibly send me a basic password-protected file and the password so I can try it? (I don't have Excel on my laptop) My email is .

Thomas

from xlnt.

Hi Thomas,

Thanks for your reply and sorry for my late reply. I just came back from a
business trip.
I attached one password protected .xlsx file for you to test, and its
password is "test".

Thanks again for your help.

Cheers,

Nai-Yuan

On Thu, Sep 22, 2016 at 8:29 PM, Thomas Fussell [email protected]
wrote:

Hi Nai-Yan,

There are two kinds of password protection. One encrypts the file, the
other just adds an attribute to the XML. The second kind should already
work since that attribute is ignored though I haven't tested it. File level
encryption is more complicated, but I should be able to implement it if
there's demand for it. Could you possibly send me a basic
password-protected file and the password so I can try it? (I don't have
Excel on my laptop) My email is [email protected] .

Thomas

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from xlnt.

Hi Nai-Yuan,

I'm afraid the attachment didn't come through on the email. It looks like you may be able to attach it here if you want to try again. I do have some updates on implementing this feature. It's been a nice little challenge reverse engineering how this encryption system works. I now have code working for reading encrypted XLSX files from before Office 2013. Newer XLSX files use a different type of encryption called Agile which I think I will be able to finish in the next few days.

Thomas

from xlnt.

Hi Nai-Yuan,

I've recently committed some code for reading encrypted XLSX files. It will require you to link with NSS which is the only cryptographic provider I could find which implements the form of encryption used by Excel 2013 and later. If you're on windows you can use the new submodule called third-party/nss to compile this library (cd third-party/nss && mkdir build && cd build && cmake .. && cmake --build .) On Linux and OS X you'll need to change the include_directories in cmake/xlnt.cmake to point to the location of your system NSS libraries installed via Homebrew or another package manager. Lastly, you'll need to compile xlnt with the new cmake definition "-D WITH_CRYPTO=1". I'll continue to make this process easier in the coming week.

Thomas

from xlnt.

Hi Thoms,

Thanks a lot for your help!
This is really an exciting news.

Cheers,

Nai-Yuan

On Oct 24, 2016 8:41 AM, "Thomas Fussell" [email protected] wrote:

Hi Nai-Yuan,

I've recently committed some code for reading encrypted XLSX files. It
will require you to link with NSS which is the only cryptographic provider
I could find which implements the form of encryption used by Excel 2013 and
later. If you're on windows you can use the new submodule called
third-party/nss to compile this library (cd third-party/nss && mkdir build
&& cd build && cmake .. && cmake --build .) On Linux and OS X you'll need
to change the include_directories in cmake/xlnt.cmake to point to the
location of your system NSS libraries installed via Homebrew or another
package manager. Lastly, you'll need to compile xlnt with the new cmake
definition "-D WITH_CRYPTO=1". I'll continue to make this process easier in
the coming week.

Thomas

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from xlnt.

It was quite complicated to implement, but I learned a lot about cryptography in the process. I managed to change nss over to botan yesterday which is significantly easier to build. Cryptography will be included with all builds now so there's no need to add "-D WITH_CRYPTO=1" to cmake. I only had a few example of encrypted XLSX files so there may be some that don't work yet. Please reopen this issue if it doesn't work for you.

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