question about KEY export funcionality

alessandro-b

Hello,
I'm new in cryptography stuffs, and I would ask you a question about the boxcryptor software.
I don't understand well how does the "Key Export" feature works.
When I log into my web account and click on "KEY Export" link, a file with *.bckey extension is downloaded into my computer.
If I look inside this file I can recognize the Private/Public RSA keys and the AES key.

Does this mean that my private RSA key and AES key are stored into boxcryptor servers?
If Yes, how they are stored? Are they coded? If yes, how are they coded?

Thanks,

Regards

Christian

Hello alessandro,

let me put your mind at ease: We don't have access to your RSA and AES keys at any point in time :-)
The keys you detected are indeed your keys, but they are encrypted by a key calculated from your password. Since we don't know your password (even during the login, we receive only the password's hash), you're the only person that can decrypt your actual encryption keys.

We have a very detailed technical overview about how our encryption (and key management) works - have a look over it at https://www.boxcryptor.com/en/technical-overview. Also, feel free to ask if you have any more questions!

Best regards,
Christian

baptisteel

Dear support,

Last week, I lost my internet connexion and then the the access to my encrypted files (the boxcryptor server couldn't check my credentials). After this bad expereincen, I decided to "export the key" if a broken internet connexion will happen again.

I've two questions:
- If I change my boxcryptor password, then I have to export key again? is that right?
- If I use boxcryptor as local account (without internet connexion), is it possible to revert to boxcryptor used online (with internet connexion)? I mean is it possible to use local account temporarly, just during broken internet period?

If I was clear enought... thank your for your reply,

Best regards

benjamin4646

Hi baptisteel,

I'm not a boxcryptor staff member, but I think I can answer your questions.

If I change my boxcryptor password, then I have to export key again? is that right?

Yes. If you change your password, then the key file will be re-encrypted with the new password, so you will need 1) an exported copy of the newly re-encrypted key file, and 2) your new password.

You should also be able to use the old exported key file with your old password to decrypt your files

If I use boxcryptor as local account (without internet connexion), is it possible to revert to boxcryptor used online (with internet connexion)? I mean is it possible to use local account temporarily, just during broken internet period?

Yes. I believe that it is possible to move between local and online accounts, as long as you have access to a copy of the key file whilst you are offline.

baptisteel

Dear Benjamin,

Thank you very much for your answer... even you're not a staff member.

Baptiste,

Florian

Hi baptisteel,

One last note:

You actually should be able to use Boxcryptor with an online Account even without an internet connection. Just make sure to never sign out.

Regards,
Florian

baptisteel

Hi Florian, you are right, but sometimes Boxcryptor ask to re-enter my login/pass and it happened when I lost my Internet connection ! Bad luck.
Thanks