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Thread: WinZip cipher

  1. #31
    npanic
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    winzip password

    Maybe i don't get it, anyway i don't understand all this crypto talk, just 2 "advanced" for me.

    Why not just bruteforce it 2 unzip the contents without entering the right password? i once wrote a little tool in Delphi that let u unzip/unrar without entering a password it also handled RARselfextracting files.
    If remember it right it could handle WinRAR 2.8/2.9 2.9Selfextract
    and WinZip 8.0/8.1beta, thats as far as i got before i found me some new stuff to play with.

    BTW, it was a simple memory patcher modyfied a bit. With the Zip's and RAR's it played with WinZip memory, and with RAR's...
    I don't remember abt the selfextracting RAR(probaly something with the caption title of the file).
    I promise that I have read the FAQ and tried to use the Search to answer my question.

  2. #32
    הבּרוּ נשׂאי כּלי יהוה mike's Avatar
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    The keyspace is 12 bytes or 8*12=96 bits. That's 4 billion times harder to brute force than the distributed.net rc5 challenge.

  3. #33
    npanic
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    ups...

    ...again i have learned, do not involve urself into stuff u absolutely not have a clue about. :-)

    - who do not ask do not learn -
    or something like that....
    I promise that I have read the FAQ and tried to use the Search to answer my question.

  4. #34
    הבּרוּ נשׂאי כּלי יהוה mike's Avatar
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    do not involve urself into stuff u absolutely not have a clue about
    wrong
    - who do not ask do not learn - or something like that....
    right!

  5. #35
    gotofbi
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    This is very very intersting thread even though it is old
    Does anybody still interested???
    I promise that I have read the FAQ and tried to use the Search to answer my question.

  6. #36
    הבּרוּ נשׂאי כּלי יהוה mike's Avatar
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    I'm happy to continue as long as someone is interested enough to ask questions and try things out for themselves.

  7. #37
    Naides is Nobody
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    "Nobody" is always interested

  8. #38
    http://www.google.com/search?hl=en&ie=ISO-8859-1&q=winzip+encryption+vulnerability&meta=

    Have phun

  9. #39
    gotofbi
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    Hmm... I have one passworded zip file which contains 4 files.
    I have 1 file which included passworded zip file.
    I tried to zip this file to same option so I can use it for PKCRACK
    When I tried to make zip file, the filesize does not match with passworded zip file.

    So... let say, in the that passworded zip file, the file shows 290.262 byte.
    I think I have to make a new zip file which contains 290.250 byte file.
    But I cant make 290.250 byte file somehow!!

    I tried all method to make zip file but it goes other byte which means it would not work with PKCRACK.

    What can I do now!?
    I promise that I have read the FAQ and tried to use the Search to answer my question.

  10. #40
    Pkcrack is not the only method... there are better ones available.

  11. #41
    gotofbi
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    Quote Originally Posted by LLXX
    Pkcrack is not the only method... there are better ones available.
    If you know the better one, how come you did not give a hint?
    I also tried AZPR but it was useles...

    The non encypted file was name with non-english letter.
    I think AZPR cant recognize non-english letter (it was Korean).

    Please share the information

    Thank you very much!
    I promise that I have read the FAQ and tried to use the Search to answer my question.

  12. #42
    הבּרוּ נשׂאי כּלי יהוה mike's Avatar
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    There are three attacks on zip files. The first is password guessing. If you know the password was korean, then you might try a dictionary attack with a korean wordlist. You should reverse-engineer the app to see if it actually does anything with korean letters though, since many zip programs don't use unicode. It may have translated all the characters to underscore or something stupid like that.

    The second attack is the known-plaintext attack, or Biham-Kocher attack. To mount this, you need a copy of one file that's in there and the same zipper program using the same compression method. This lets you get the password and decrypt the other files you don't have.

    The third attack is an attack on the random number generator, or Stay attack. This one works if there are more than four files and the zipper uses InfoZip's random header generation method. Since InfoZip was open source, most people used their code for implementing that.

    It sounds as though you have a zip file with four archived files inside. If you know one file, you can use the known-plaintext attack. The Stay attack only works if the zipper used InfoZip's method for generating headers, and it's really iffy unless you have five files. You'd have to reverse-engineer the zipper to find out.

    Naides: I'm happy to answer questions, but this thread died a couple years ago, and I'm not sure what people want to know. So if you have a question about any of the attacks, ask it and I'll see what I can do to clear it up.
    Last edited by mike; October 25th, 2006 at 11:22.

  13. #43
    gotofbi
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    I also though about the answer will be known-plaintext attack.
    But the problem is, I dont know what program and compression method used for encypted zip.
    I think I tried most of known zip program and compression method but I was not able to make same compressed size.

    Let say, one file's compressed in encypted zip was 29,600,480 byte
    Based on that information, I think I have make a zip which includes 29,600,468 byte compressed file.
    But I cant make that file somehow.

    Is there anyway to figure what the encypted zip was made by??

    PS: Im very sure that the file is exactlly same because when I compared the file's CRC with encypted zip and the zip file that I made were same.
    I promise that I have read the FAQ and tried to use the Search to answer my question.

  14. #44
    הבּרוּ נשׂאי כּלי יהוה mike's Avatar
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    Quote Originally Posted by gotofbi
    Is there anyway to figure what the encypted zip was made by??
    No, there isn't. And unless you know which program it was, the compression varies too much from one program to another to be able to use the attack.

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