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Thread: how to decrypt *.rar file ?

  1. #1
    icray
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    how to decrypt *.rar file ?

    it is difficult to decrypt *.rar compressed by winrar because it use crc code.But I have heard someone can decrypt it without passwd .I think maybe they use the winrar bug.And someone can decrypt files compressed by winrar 3.x algorithm ?
    I promise that I have read the FAQ and tried to use the Search to answer my question.

  2. #2
    Results 1 - 10 of about 4,610 for rar decryption.
    Still here...

  3. #3
    Naides is Nobody
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    Quote Originally Posted by icray
    it is difficult to decrypt *.rar compressed by winrar because it use crc code.But I have heard someone can decrypt it without passwd .I think maybe they use the winrar bug.And someone can decrypt files compressed by winrar 3.x algorithm ?
    RAR uses AES (Advanced Encryption Standard) 128 bits, not CRC, which is something else. So far bruteforce/dictionary attack (and time) are the method of choice for decryption. You may be mistaken with zip encryption, which is weak. Or am I wrong?

  4. #4
    naides, I believe you're almost right. Off the top of my head, Winrar 2.x and Winzip 7 used weak encryption that could be broken with some simple "collision work". Don't ask me what, I just seem to remember an app that did it.

    Quote from the WinRAR faq:
    What is the difference between WinZIP and WinRAR encryption?

    ZIP format uses a proprietary encryption algorithm.

    RAR archives are encrypted by the much stronger AES-128
    standard. If you need to encrypt important information,
    it is better to select the RAR archive format.
    WinZIP 8 and higher use AES as well:

    AES Encryption Information:
    Encryption Specification AE-2.
    The AE-2 encryption specification described here involves a minor change to the AE-1 encryption specification covered in the original May, 2003 version of this document. The recent changes to this document are summarized in the Change History section below. Without compromising the basic Zip file format, WinZip Computing has extended the format specification to support AES encryption, and this document fully describes the format extension
    So, um, WinRAR FAQ needs updating
    Incidentally, this is pretty interesting: http://www.cs.ucsd.edu/users/tkohno/papers/WinZip
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  5. #5
    Registered User cRk's Avatar
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    gzipped-PostScript .. i downloaded this document and extract it but the document always gets opened with paint shop Pro .. and can't see nothing ... which program should i use for this .ps (postscripts) documents ??

    Regards

  6. #6
    download GhostView + GhostScript

    adobe acrobat can probably open it though.

  7. #7
    Registered User cRk's Avatar
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    Adobe acrobat reader don't
    recognize it or even try to open it .. looking for ghostview...

    Regards
    Last edited by cRk; August 4th, 2004 at 13:37.

  8. #8
    icray
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    yeah, i think i make a mistake.And silver, the app you mean is passware? It need at least 5 files to decrypt. Why it need 5 files?
    I promise that I have read the FAQ and tried to use the Search to answer my question.

  9. #9
    Formal
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    See what Eugene Roshal (the author of WinRAR) says:

    Q: I forgot my password, please help me!

    A: WinRAR encryption does not have any backdoor. Even if I forget a password to any my archive, I shall not be able to restore it. So please do not ask me to help in this situation.

    So, as naides said - bruteforce or dictionary attack. I don't think anyone can do it anoter way and I doubt there is such bug in the encription routine, that allows decryption without password.
    I promise that I have read the FAQ and tried to use the Search to answer my question.

  10. #10
    Peres
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    Careful with that axe, Eugene...
    I promise that I have read the FAQ and tried to use the Search to answer my question.

  11. #11
    I don't think it's passware, I really don't remember the name of the app. But the reason it needs 5 files is probably because of whatever collision thing it uses.

    Hey, look at me, clutching at random straws...
    Still here...

  12. #12
    arash
    Guest
    Quote Originally Posted by icray
    yeah, i think i make a mistake.And silver, the app you mean is passware? It need at least 5 files to decrypt. Why it need 5 files?
    how i can remove rar password?
    I promise that I have read the FAQ and tried to use the Search to answer my question.

  13. #13
    Quote Originally Posted by arash
    how i can remove rar password?
    are you joking ? did you not read what has just been said?

  14. #14
    Quote Originally Posted by doug
    are you joking ? did you not read what has just been said?
    Heh, I agree. Learn to search before asking simple questions like that. There are many password crackers out there that you can find with a simple search.

  15. #15
    Administrator dELTA's Avatar
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    how i can remove rar password?
    Oh, for the love of god, not one of those again...

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