Determine what encryption was used

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• Author
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If I have a file with an .enc extension is there any way that I can
tell what type of encryption, AES or Blowfish, was used?

Re: Determine what encryption was used

If you have the key, use it in both and see which one decypts the file.
Otherwise no.

Re: Determine what encryption was used

The file extension .enc is used by a number of programs, many of
which have nothing to do with encryption.

Here's a reference to the file format of a .enc file for an AES
encryptor. If you examine the format given there, you will see there is
nothing there which would indicate what kind of encryption is in use.

Other programs that generate .enc files might or might not contain
information that indicates the algorithm type, but to say more about
those, we would have to know which program you are using.

Re: Determine what encryption was used

Nope, not the algorithm, that's sort of the point...

Re: Determine what encryption was used

[Apparently in response to someone writing]

Amongst other things, it would have saved me from having to dig through
previous postings to find the original question to restore into
the conversation.

No, I'd have to disagree. AES and Blowfish were both designed to
be computationally very expensive to break *even knowing the algorithm*.

At most, not knowing whether the file was encrypted with AES or Blowfish
doubles the work involved -- the equivilent of adding one more bit to
the key. That's not an important difference compared to the average
2^191 (3138550867693340381917894711603833208051177722232017256448)
operations required to break AES-192.

The .enc file could potentially have included the plaintext string:
JoshCrypt 3.72/AES-192
and it would not have materially affected the difficulty of decryption.

Re: Determine what encryption was used

Yeah, not my point. I was basically saying that you can't tell by
merely looking at cyphertext what algorithm was used to encrypt, as it
is random, which is indeed the point of encryption. If someone (vendor)
wanted to slap a little header on an encrypted file (or wrap it around
said file), more power to them.

Sorry for the ambiguity, I forgot how much people assume everyone's a
moron (except themselves) on here.

Re: Determine what encryption was used

If you had quoted the context, you would have been reminded that the
question was:

which is a *file* level question, not a payload-level question. And
in terms of *files* we cannot answer it because the ".enc" extension is
not sufficient for us to pin down the originating program.

Is that from the same author who recently wrote,