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  1. #1
    Senior Member
    Join Date
    Aug 2001

    breaking RSA on a ZIP file? possible ona home pc for a forensics uni prize?

    lemme first state that what im asking here is legit, for a computer forensics prize a local company is running with our uni... www.ionix.com.au/?p=csfprize

    go there to see that this is legit if you like...

    what my problem is, ive recovered and repaired a zip file on the disk, copied to my PC and i'm not sure whether im meant to try and decrypt these files or not, theres 3 in the file all encrypted with RSA...

    im not sure if its 'real' RSA or just a weak version that would be crackable on a home PC, anyone know of how this could be done or whether its realistically possible even with a small number?

    and let me say again, this is a legit comp, so dont neg me to hell and back please

    i've attached the file too if you would like to look at it to see what you think

  2. #2
    AO übergeek phishphreek's Avatar
    Join Date
    Jan 2002
    Well... this may be something of interest...

    Or this...

    There are quite a few more.


    I haven't found a program to crack it... just ways that it can be cracked.

    Hopefully you know how to program.

  3. #3
    Senior Member Maestr0's Avatar
    Join Date
    May 2003
    "RSA is typically performed using 512 bit prime numbers. There are approximately 3.778e151 such prime numbers. Using the advanced storage technology available to the NSA, it should be possible to store a 512 bit number in a single hydrogen atom. A typical universe (e.g. ours) contains approximately 1e90 hydrogen atoms. If the NSA has hidden 3.778e61 universes in an inconspicious little building in Maryland, astronomers should notice some deviations in the gravity field in the area." Basically, your're not going to crack RSA, you MIGHT however crack a weak password via BruteForce.I believe what you're going to need is something like http://zipcracker.bengburken.net/ and some spare time. Good luck!

    \"If computers are to become smart enough to design their own successors, initiating a process that will lead to God-like omniscience after a number of ever swifter passages from one generation of computers to the next, someone is going to have to write the software that gets the process going, and humans have given absolutely no evidence of being able to write such software.\" -Jaron Lanier

  4. #4
    Senior Member
    Join Date
    Jul 2003
    Definatly brute force the passwords, It's very doubtable youd crack a true RSA algothim with a home PC,

    I mean if the passwords are strong and your at a uni surely u could use the netwrok to do a distributed brute force attack on the files.

    i think i noticed was that when you try and extract the files, its passworded then as well, What about using softIce then and seeing if you can crack it that way, I think its softIce ive forgotten to be honest.

    also, i havent played with Zip files much but what about using debug, and then you might be able to pull out bits of the datafiles, place them in a Zip and then decompress them that way, Just an idea (likely to fail)

    daft as it my sound but the files are all named the same, are they all the same? they look like it cos there all the same size, but its impossible to tell at the moment

    Im sure theres programs to crack ZIP passwords, but you could write one simple enough, if you used softIce and found the location on the text entry and then created a program to hammer passwords at that location

    probably be easier to just defeat the password with cracking/reverse engineering in that case


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