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BACKGROUND:

I have already created a passphrase list to use with bruteforce-luks. Unfortunately, that list was not enough to find the correct passphrase. I am assuming I missed out a word or 2.

I am fairly sure some or all of the words are in the actual passphrase, but I am unsure of the remaining possible 1 to 3 words.


REVISED QUESTION:

I think between 1 to 3 words are missing. What's the best approach for me to use? I can't seem to remember what those words would be.


ORIGINAL QUESTION:

How would I go about attempting to use bruteforce-luks across 4 servers?

The servers are in a single building, and are currently loaded using a Linux Live Disk.

I have a usb stick which is luks encrypted and have forgotten the passphrase. Tried to bruteforce it at home, but my 2 core CPU was only giving me 4 passphrase attempts per second.

I'm hoping to make use of the 8 cores per server (32 cores in total) at the same time to attempt to speed up the bruteforce processing.

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  • Do you know anything from that passphrase? If not, bruteforcing luks with strong passphrase is impossible and a waste of ressources. Even more if you want to use CPU and not GPU.
    – pLumo
    Jan 24, 2019 at 9:54
  • Yes, I have reduced the character set to about 32, with a minimal length of 10 characters. I did attempt a passphrase list file, but I guess I missed out a word or 2. Jan 24, 2019 at 10:37

1 Answer 1

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Solution:

  1. Create program which allows you to type in all the words you usually use in passwords.

  2. Run the program which will do a sort of permutation but not only change the order of the words, but also build up the number of words used per permutation.

  3. Save the generated passphrase text file (ended up being over 5,000,000 passphrases)

  4. Use the 32 cores I had available and split the passphrase text file into 4. I file per server.

  5. Use dd to create an additional 3 copies of the USB stick which needs to be brute-forced

  6. Plug 1 USB stick into each of the 4 server, and 1 forth of the text file per server.

  7. Install and run bruteforce-luks with all cores and all server and around 24 hours later, the passphrase was found.

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