I noticed after encrypting some files with 7zip that they contained the information about the encryption algorithm used AES 256, i want to know if there is a better software that doesn't leave traces about the nature of encryption because with such information this will simplify the task of deciphering by the attacker.

I think that the security wouldn't be good if the encryption software is adding metadata or inserting an ID somewhere in header leaving hints about the nature of file (7zip compressed), the version used and the encryption algorithm name.

What can you suggest ? thank you

  • Unfortunately, questions of the type "what product/service does X?" are off-topic. If you want to rephrase your question about whether this metadata is a problem, we can re-open. – schroeder May 26 '20 at 10:10

I don't agree that such information should be secret. Think of Kerckhoffs's principle. Security should be based not on the secrecy of method, but on the secrecy of the key.

  • Don't you think that hiding the fact that a file is encrypted would keep the file safe from being an object of attack, this is my point. – P. Kod May 25 '20 at 22:08
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    When you are encrypting anything, you should expect that it will be an object of analysis and brute-forcing. – mentallurg May 25 '20 at 22:11
  • Yes but in other words i said that hiding an encrypted file could make it appear like if it's not encrypted at all, why would you try to brute-force a file you don't know if it's encrypted or just filled with random data ? – P. Kod May 25 '20 at 22:17
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    @P.Kod: When you are encrypting anything, you should expect that it will be an object of analysis and brute-forcing. Computer programs produce the same output for the same input and are relatively easily analyzable. Making encryption method obscure gives only impression to humans that this gives more security, where as actually it doesn't. – mentallurg May 25 '20 at 22:17
  • @P.Kod: ... Because if somebody wants to find out any information you want to keep secret, he/she will analyze any data they obtain. They will not analyze if a particular file contains a hint encrypted by method ABC. For instance, if particular file is not distinguishable from a random byte stream, it can be really garbage, but it can also be an encrypted data. If s file has some structure (like image), it would be checked against possible steganography. – mentallurg May 25 '20 at 22:23

Any given encryption system should be secure even if everything except the key is public. This is a basic principle of encryption as stated by Kerckhoffs.

VeraCrypt for example offers the creation of "hidden volumes" which not only make it not obvious which encryption algorithm is used, but also hide that there actually is anything encrypted.

Although according to VeraCrypt's documentation, this is more of an approach to prevent extortion when attackers know that there might be some sensitive information around. Normally, the humans knowing the access procedure are much weaker than the encryption algorithms used.

Notice: This can also be the other way around. Attackers sometimes back off when seeing that a very secure and slow algorithm is used for encryption as very secure algorithm often come along with secure keys. This does NOT mean, that you should use insecure algorithms!

  • Yeah but the concept of hidding volumes in Veracrypt supports my point of view, there is a need to conceal that a file is encrypted, if an attacker couldn't say if an encrypted volume exist would increase the security of data the same applies to individual files, if no hints are there the attacker couldn't tell if the file is encrypted or a corrupted video file for example. – P. Kod May 25 '20 at 22:03
  • Attackers sometimes back off when ... - why do you mention this at all? It sounds like you believe that the encryption you use is actually weak and you fear that attackers will break it, and you will be happy if they don't continue. Such view might implicitly promote usage of insecure methods based just on the hope that serious attackers will not spend time analyzing and brute-forcing them. – mentallurg May 25 '20 at 22:09
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    @mentallurg What about hidden volumes then ? It's not about not trusting the encryption algorithm, it's about not giving hints that a given file is encrypted or encrypted using a particular method, i search something that will output a raw file that couldn't be identified that it's encrypted without doing extra analysis work. – P. Kod May 25 '20 at 22:22
  • @dmuensterer: Assumptions? :) I am just wondering what can be the reason. Many users that will read this statement may believe that one of methods to get security is to keep attackers off. Thus based on your answer they can implement insecure methods hoping that some trick they implemented will keep attacker off and will give them security. Where as this will of course give no security. – mentallurg May 25 '20 at 22:27
  • @P.Kod: Hidden volumes can help only against beginners who don't really understand cryptography. – mentallurg May 25 '20 at 22:30

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