Determine what encryption was used - Security

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Thread: Determine what encryption was used

  1. Determine what encryption was used

    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?


  2. Re: Determine what encryption was used

    "JediKnight2" writes:

    >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?


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



  3. Re: Determine what encryption was used

    In article <1145364776.454429.183260@i39g2000cwa.googlegroups. com>,
    JediKnight2 wrote:
    >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?


    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.

    http://fp.gladman.plus.com/cryptogra...y/fileencrypt/

  4. Re: Determine what encryption was used

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


  5. Re: Determine what encryption was used

    [Apparently in response to someone writing]

    >>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?


    In article <1146081022.842360.320950@y43g2000cwc.googlegroups. com>,
    Joshua Reed wrote:

    Please quote context. Please see here for information on how to
    do so from Google Groups: http://cfaj.freeshell.org/google/
    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.

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


    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 (3138550867693340381917894711603833208051177722232 017256448)
    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.


  6. 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.


  7. Re: Determine what encryption was used

    In article <1146190615.093047.132830@i40g2000cwc.googlegroups. com>,
    Joshua Reed wrote:
    >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 you had quoted the context, you would have been reminded that the
    question was:

    >>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?


    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.


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


    Is that from the same author who recently wrote,
    Wow, that was an undetailed reply. You expect someone asking
    that question to know what to do with this answer?
    ?

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