Originally posted here by thehorse13
Someone asked me a question and I think the answer should be posted.

If you zip a file, the file header CRC value will be the same as the data file CRC. Once you go through the tut, zip a file and you'll be able to spot the CRC values in the hex table within seconds.

Someone else asked me about hiding data within files. Yes, that is called steganography and is a common practice. No, I haven't done a tut on stego - yet.

Ascii Stegonagraphy:

I'm making this up as I go along, so it may suck, I don't care though:

---------------------------------- -----------------------------------------
------------------------ ------------------------------
---------------- password for nukes is kjbdsfkjndskfvkdjfvkjdfv ----------------
--------------- ---------------
--------------- ---------------
--------------------------- ----------------------------
---------------------------------- ----------------------------------------

See in that picture of the sky the password for some weapons is hidden within the data.

OK so that isn't EXACTLY how it is.... Actually it sort of is. Say in the picture you're looking at on your screen there is a red shade in the image. Well, each pixel showing red was told to show red by the computer and the computer only thinks in Binary. Well, say red is in the image and shows up to the computer as 10001011 10001011 10010101 10010101 10001011 10010011 10010101 10011011

Well you could change the last 1 of each binary string there to something else and the image wouldn't look any different to a human eye. The tone change would be so small you wouldn't be able to tell. So you could form a message in the code for red that would say something because you now have a few more bits to work with text.

So I could change that to say a password for something, and only the people who know to check it with Stego tools would be able to decode it.

Ahhh the art of hiding in the open.

So it is kind of neat. You change one bit, no one can tell really, and in that bit you hide messages for people. well, not in ONE bit, but in the bits you change you can fit a whole email message for some. It's kind of neat really. Terrorists use it too.....lol.