CompOrg Binary Bomb Squad

Due Date: 10/17/02 (by 11:59:59PM)
Only Electronic Submissions!

Late Penalty: 10% per day

This counts for two homeworks!

You have been selected to be a member of an elite group of cyber-techno-digi-gurus who are needed to defuse some binary bombs. Your have been selected due to your expertise in X86 assmembly language, your knowledge of data representation and computer arithmetic, and your extensive knowledge of how to read an ASCII reference chart.

You will be given a "binary bomb" which you must defuse. If you are not capable of defusing the bomb, one of two possible things will happen:

1. You will get a bad grade on this assignment.
2. The world will end.

I can't remember which will actually happen... feel free to use whichever one provides you with more motivation.

A binary bomb is an executable program that consists of six phases. Each phases expects the user to enter a particular string (via stdin). If the expected string is entered, the phase has been defused and the progam moves on to the next phase. If the expected string is not entered, the program explodes (prints "BOOM" and quits). Your job is to defuse as many phases as possible.

Each phase tests a different aspect of machine language programs:

There is also a challenging "secret phase"... (but it's a secret)

Each student will get a unique bomb, the solution to your bomb (the sequence of expected strings) is different than everyone else's. Feel free to help each other with general concepts (you can work together), but you are not allowed to submit solutions to your bomb unless you determined the solutions. In other words - if you need help, feel free to ask Dave or the TAs or anyone else to help you get started, but you must have a complete understanding of how to figure out what the solution is (you will certainly need this ability on a test!).

The phases are ordered in increasing difficulty, and phase 1 is pretty easy. Don't underestimate the project just because you can solve the first phase - the subsequent phases get harder!

There are bombs available for each of the Unix-environments listed below. To get a bomb for your environment just click on the appropriate icon.

Linux		cygwin		BSD

Your bomb will be sent in a zip file that includes:

• The actual executable program named bomb (or bomb.exe for cygwin).

• A file named ID that identifies your bomb. When you submit your solutions you will need to send back this file (it identifies your bomb so we can verify that your solutions are correct!). Your bomb ID must be unique, it is not acceptable for multiple people to submit solutions to the same bomb!

• A file named bomb.c. This is the actual C code for the main program. You don't really need this, but it may be helpful to understand what the main program is doing. You don't get the C code for the actual phases, the point of this assignment is that you need to determine what they are doing just by looking at the assembly language code (which you can get by disassembling the executable program).

We assume that you can handle a zip file! Under Windows you can use WinZip (available at www.winzip.com). Under Unix you can use unzip to unzip a zip file.

NOTE: The "bomb server" that sends you a binary bomb (when you click on one of the above icons) will make sure that your bomb is not available to anyone else! It is not acceptable that two students submit the same bomb ID - everyone needs to download a unique bomb (with a unique solution!). Each student needs only one bomb, so please don't download lots of them (there are a fixed number of bombs pre-made, and if the server runs out this will inconvience other students who have not yet received one bomb!).

Submission of your homework is via email, the general idea is to send an email message with your solution and bomb ID file as attachments. There is an automated email submission system that will respond to your submission right away, so you will have a record that we got your file.

All projects must be submitted via email to comporg-submit@cs.rpi.edu. The subject line of the submission message should contain a single number '3' indicating the HW number. Your submission must include the following:

• A file named "solution.txt" that contains the solution (the sequence of strings required to defuse your bomb). This file should contain one line of text for each phase you completed, and sending the bomb this file (via redirection of STDIN) should prove that your solutions are correct:

  ./bomb < solution.txt 
  Welcome to my bomb. You have 6 phases with
  which to blow yourself up. Have a nice day!
  Phase 1 defused. How about the next one?
  That's number 2.  Keep going!
  Halfway there!
  So you got that one.  Try this one.
  Good work!  On to the next...
  Curses, you've found the secret phase!
  But finding it and solving it are quite different...
  Wow! You've defused the secret stage!
  Congratulations! You've defused the bomb!
  

  If you don't get all the phases solved, just tell us about the phases you did not solve in another file or the body of your message.

• A file named "ID" that identifies your bomb. You are given this file when you download your bomb - you must send it back with your submission.

IMPORTANT! Make sure your email message includes your full name, we can't record your grade unless we know your name!

Don't send your bomb program in your submission! These programs are dangerous and we certainly don't want to be messing with them (that's why we have you experts handing things...).

You can expect a return email indicating receipt of your project submission immediately. This receipt will include a list of all the files that were successfully extracted by the submission script - please look over the receipt carefully to make sure your submission worked.

Multiple Submissions: You can resubmit up to 10 times for each project, we will always grade the last submission received unless you tell us otherwise.

Grades will be determined by the number of phases you are able to solve:

• Phases 1-4 are worth 20 points each.
• Phases 5 and 6 are worth 10 points each.
• 10 points extra credit for anyone who can solve the "secret phase".

It is possible to get partial credit for a phase (up to 1/2 the points). To get extra credit you need to include a description of how far you got figuring out the phase (show us the assembly code and describe what you think is happening, etc). Partial credit points will not be awarded if we can't understand your description (you need to make sure that you convince us that you have some understanding of what is happening in the code for the phase).

| 00 nul| 01 soh| 02 stx| 03 etx| 04 eot| 05 enq| 06 ack| 07 bel|
| 08 bs | 09 ht | 0a nl | 0b vt | 0c np | 0d cr | 0e so | 0f si |
| 10 dle| 11 dc1| 12 dc2| 13 dc3| 14 dc4| 15 nak| 16 syn| 17 etb|
| 18 can| 19 em | 1a sub| 1b esc| 1c fs | 1d gs | 1e rs | 1f us |
| 20 sp | 21  ! | 22  " | 23  # | 24  $ | 25  % | 26  & | 27  ' |
| 28  ( | 29  ) | 2a  * | 2b  + | 2c  , | 2d  - | 2e  . | 2f  / |
| 30  0 | 31  1 | 32  2 | 33  3 | 34  4 | 35  5 | 36  6 | 37  7 |
| 38  8 | 39  9 | 3a  : | 3b  ; | 3c  < | 3d  = | 3e  > | 3f  ? |
| 40  @ | 41  A | 42  B | 43  C | 44  D | 45  E | 46  F | 47  G |
| 48  H | 49  I | 4a  J | 4b  K | 4c  L | 4d  M | 4e  N | 4f  O |
| 50  P | 51  Q | 52  R | 53  S | 54  T | 55  U | 56  V | 57  W |
| 58  X | 59  Y | 5a  Z | 5b  [ | 5c  \ | 5d  ] | 5e  ^ | 5f  _ |
| 60  ` | 61  a | 62  b | 63  c | 64  d | 65  e | 66  f | 67  g |
| 68  h | 69  i | 6a  j | 6b  k | 6c  l | 6d  m | 6e  n | 6f  o |
| 70  p | 71  q | 72  r | 73  s | 74  t | 75  u | 76  v | 77  w |
| 78  x | 79  y | 7a  z | 7b  { | 7c  | | 7d  } | 7e  ~ | 7f del|