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Thread: What is packing/unpacking ?

  1. #1

    Post What is packing/unpacking ?

    I searched this forum, and although I found a lot of articles on packing tools and unpacking tools, I did not find one which can explain what is packing/unpakcing. How is it different from encryption/decryption/cryptography ?

    Can some body explain me ? Or point me to a direct link ? Please dont give a link which in turn has hundreds of other links. Please give a few direct links.
    I promise that I have read the FAQ and tried to use the Search to answer my question.

  2. #2
    Naides is Nobody
    Join Date
    Jan 2002
    Planet Earth

  3. #3


    There's a reason we don't tell you: YOU are supposed to figure it out YOURSELF.

    Two words: LURK MORE.

  4. #4
    What they are trying to tell you is that this is not a Kindergarten for Cracking where someone takes you by the hand and leads you to the caulkboard and teaches you all you need to know about some aspect of the "Art of Cracking."

    The "Art of Cracking" is a "process" and is acquired by "personal effort," something which your Post suggests you are not too willing to expend. Had you actually READ THE FRIGGIN FAQ you would already have been aware that we have certain expectations of Posters here, one of which is that they devote some "personal effort" at attempting to find the answer to their "own question" before they post it here. And, if they have expended that "personal effort," they can avoid the anticipated criticism, by simply stating they actually attempted to find the answer to their question.

    In your case, although you state that you saw alot of articles on tools for "packing/unpacking," you apparently made no "personal" effort to investigate, for yourself, what "packing/unpacking" might be. Attempting to find the answer to such questions is WHY the Diety invented the internet and its various search engines. Had you shown at least some minimal effort to use such readily available tools, you would have easily avioded criticism and would not have needed to post your question.

    For example, you should have seen some significant discussion of one of the basic "packers" and tools for "unpacking" UPX. Had you simply put UPX in your favorite search engine you would have gotten to many discussions of UPX, including one which is a Wikipedia article on UPX. It contains a simple, and rather obvious discussion of the topic of packers and unpackers with such language as:

    "Executable compression is the process of compressing an executable file and prepending a decompression stub, which is responsible for decompressing the executable and initiating execution. The decompression stub is a stand-alone executable, making compressed and uncompressed executables indistinguishable to the casual user, as they are not required to perform any additional steps to start execution.

    Software distributors use executable compression for a variety of reasons, primarily to reduce the secondary storage requirements of their software; however, as UPX is specifically designed to compress executable code, it often achieves better compression ratio than standard data compression facilities such as gzip, zip or bzip2. This allows software distributors to stay within the constraints of their chosen distribution media (such as CD-ROM, DVD-ROM, or Floppy disk), or to reduce the time and bandwidth customers require to access software distributed via the Internet."

    Another reason for compression is explained as:

    Disguising the nature or function of an executable is sometimes desirable in order to prevent reverse engineering. UPX can be used to prevent direct disassembly, mask string literals and modify signatures. Although this does not eliminate the chance of reverse engineering, it can make the process more costly."

    Now, with just a "modicum of effort," you could have found this or similar information using just a little personal initiative and some simple brain functioning. So before you protest your treatment, consider first your own responsibility for your own lack of significant effort as the root cause.


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