Typos and bug fixes:

• no fixes of note

Continuing our “1337 haxxing” series of projects, we've found considerable conceptual self-imposed roadblocks blocking our employment of otherwise simple computing properties (that data is a series of bytes, and ultimately, that everything is a file).

We resume our exploration with another practical example, this time based on real data generated by an EEG device. The intersection of hardware, software, and logic play vital roles in problem solving activities (even if it is just enabling analysts to make more educated guesses), and seems to be a skill increasingly taken for granted and alien.

An electroencephalogram (EEG) is a test that detects electrical activity in your brain. Brain cells communicate via electrical impulses and are active all the time, even when you're asleep. This activity can be visualized as wavy lines on an EEG recording, but ultimately is sourced from raw bytes sampled from the device performing the data acquisition.

Sleep

This week's project is located in the spring2015/udr1/ directory of the UNIX Public Directory, in a file called: data.file

Make a copy of this into your home directory somewhere and set to work.

NOTE: Hopefully it has been standard practice to locate project files in their own unique subdirectory, such as under src/unix/, where you can then add/commit/push the results to your repository (you ARE regularly putting stuff in your repository, aren't you?)

The data you seek (2 files) is obfuscated and contained within this file.

Plain text directions give clues on how to find both pieces of information, and it is up to you to use your skills to extract the necessary data.

Some additional information:

• The first file should be named udr1.text and be properly oriented.
• The second (big) file runs from the starting point until the very end of the file
• It should be named 'gizmo', and reside in your current working directory.
• gizmo is binary data, and entirely reversed- you need to get its bytes back in order (last byte should be first byte, 2nd to last should be 2nd, etc.)
  • You are to write a shell script to perform the de-reversal of the data, reading from data.file and through whatever processing is needed, produce the file called gizmo.
• The urev tool has some additional constraints with respect to gizmo… running it should notify you of any details you are lacking.

You may want to become familiar with the manual pages of the following tools (in addition to tools you've already encountered):

• dd(1)
• bc(1)
• du(1)
• bash(1) shell scripting
• od(1)
• bvi(1)
• hexedit(1)

… along with other tools previously encountered.

Successful completion will result in the following criteria being met:

• Resulting file with proper settings should enable you to run urev tool.
• You have completed all weekly exercises (96, I think) before the deadline, being mindful of the intentionally-paced nature of urev.
  • Bonus opportunity: while still performing a minimum of 3 distict urev sessions, how could you get around the urev-imposed time limit? (Without copying/changing urev).
• When all is said and done, you will submit 3 files:
  • udr1.text
    • Append the dd line(s) as well as any other command lines needed to extract and properly re-orient the file. Also be sure to indicate what is in the file you found (content, not just type of data).
  • your bash script enabling the processing of data.file to produce gizmo
    • Be sure to include comments indicating the reasoning behind actions taken
  • Your extracted/processed gizmo file

Please submit as follows:

lab46:~/src/unix/udr1$ submit unix udr1 udr1.text getgizmo.bash gizmo
Submitting unix project "udr1":
    -> udr1.text(OK) 
    -> getgizmo.bash(OK)
    -> gizmo(OK) 

SUCCESSFULLY SUBMITTED
lab46:~/src/unix/udr1$