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 Forums >>  Brainstorms - General  >>  Determining File Format (Compressed and/or Encrypted)

Topic created on: January 26, 2008 00:40 CST by Amadeus .

Are there any HOWTOs out there for learning how to determine the format of a file?  I am working on a particular reverse engineering project in which the application includes custom .xxx files that I believe are compressed zlib (or something similar) type of files.  So, I need to learn how to determine how the headers of the files work...and then how to write an application that will deflate/decompress the file.

thanks!

  esizkur     January 26, 2008 03:29.25 CST
Not exactly a tutorial, but software for you to look at: Fiin, the Firmware Inspector, does something similar to what you want to achieve I think: http://freshmeat.net/projects/fiin/

Cheers,
R

  lallousz     January 27, 2008 15:18.42 CST
You may detect file format just by looking at it in a hex viewer, however that depends on your experience and how many files you've inspected and identified in the past.

However, the sure and certain way is to disassemble the program that uses the file in question, and by reversing the program you will learn to deconstruct the file's format.

That is not a simple process if the file has a complex format.

One nice tool to help you reverse engineer a file format is: 010 Editor, which has templates and struct tool and scripting language...

HTH,
lallous

  frankboldewin     January 28, 2008 03:49.59 CST
i usually use TrID for file identification.

linux: http://mark0.net/download/trid_linux.zip
win32: http://mark0.net/download/trid_w32.zip

and the latest database file is here:
http://mark0.net/download/triddefs.zip

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