Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!rex!barnett
From: barnett@rex.cs.tulane.edu (Karey Barnett)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Any way to recover encrypted .zip?
Message-ID: <7765@rex.cs.tulane.edu>
Date: 5 Jun 91 00:33:28 GMT
References: <44102@netnews.upenn.edu>
Distribution: usa
Organization: Computer Science Dept., Tulane Univ., New Orleans, LA
Lines: 37

In article <44102@netnews.upenn.edu> mfontana@eniac.seas.upenn.edu (Mark A Fontana) writes:
>
>Well, I'm stupid.  I encrypted some personal files in a .ZIP before leaving
>on a trip.  Two weeks later, I've forgotten the key (thought I would
>remember it- Murphy's Law).
>
>So, is there any little utility or trick to recover the archive, or
>should I keep guessing?  I am using Pkzip 1.1 with the USA encryption.
>
>
    As an intense solution, you might want to write a program to generate
    the password by using all of the different, possible combinations
    of ASCII characters in sequence.  To cut down on the possible
    combinations, you can limit the character search to the one's
    that you very often use, in addition to setting a maximum
    strength length.

      For example, if there is a chance that you used
    a password <= 10 characters in length, specify the maximum length to
    10.  This would produce 256 to the exponent of 10 different, possible
    combinations of passwords, with only one (of course), the correct
    one.  (Using all of the 256 ASCII characters).

    But, if you limit the characters to search to perhaps
    numbers and alphabets (both capital and lower-cased), if you
    used them, then this will have 62 (10 numbers + 26 lower case +26
    upper case) to the exponent of 10 possible combinations.
    Assuming only lower-cased letters in the password, then there
    are 26 to exponent of 10 possible passwords...

	Another factor to the solution is incorporating the calculated
    password with pkunzip.   You might need to do an exec of pkunzip
    with the password within your program, or come up with a clever
    way using a batch file that takes in command line parameters to
    run pkunzip.

    Thus, you have my suggestion, which as I said before, is intense.