If I have a SSL private key that is encrypted with a DES password, and I have to share with another admin a NODES copy of the private key, can the other admin determine what my DES password is?

  • You don't say what kind of encryption you mean, and they vary enormously, but I'm going to guess you mean one of the formats and related encryptions used by OpenSSL, because openssl commandline sometimes uses the flag -nodes (lowercase) to indicate an unencrypted privatekey file, and no other common tool I know of does so. I have commented accordingly. In any case having the unencrypted file doesn't help; all possible attacks are directly on the encrypted file. Jan 16, 2019 at 3:07
  • Could you update your question with the password generation that you use?
    – kelalaka
    Jan 16, 2019 at 10:46

2 Answers 2


Not easily. This would amount to a known-plaintext attack on DES -- the "attacker" has access to a pair of ciphertext and plaintext, and is attempting to determine the key. DES is not a particularly strong cipher, but it is not considered to be especially vulnerable to this attack.

  • Even recovering the DES key doesn't give the password; see my comment on kelalaka's answer. Jan 16, 2019 at 3:17

It really look into the money that one can spend on it. For example, the Copacobana from 2007:

With further optimization of our implementation, we could achieve a clock frequency of 136MHz for the brute force attack with COPACOBANA. Now, the average search time for a single DES key is less than a week, precisely 6.4 days. The worst case for the search has been reduced to 12.8 days now.

Recently there is another one crach.sh

we’ve built a system with 48 Virtex-6 LX240Ts which can exhaust the keyspace in around 26 hours, and have provided it for the research community to use. Our hope is that this will better demonstrate the insecurity of DES and move people to adopt more secure modern encryption standards.

They can also find the key in 25 seconds with a prebuilt rainbow table built for a predetermined plaintext-ciphertext pair.

  • 1
    That recovers the key used for the DES encryption, and the plaintext (which in this example the attacker already has), but not the password from which it was derived. If the password is weak (and most are) and this is OpenSSL 'traditional' format with its awful PBKDF (MD5, unsalted, ONE iteration) john or hashcat or similar can find it quickly, but if it's PKCS8 with PBKDF2 (HMAC-SHA1 or better, salted, 2048 by default and optionally more in 1.1.0+) or if the password is strong, maybe not. Jan 16, 2019 at 3:12
  • @dave_thompson_085 Thanks for the password case that I completely forgot.
    – kelalaka
    Jan 16, 2019 at 9:50

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