Practicum in Trading Systems Development: Lab 7

Due:           Thursday, August 9, 2012, by 5:00 PM

PURPOSE AND RATIONALE

The purpose of this lab is to let students gain specific experience with basic message queue manipulation in C (called from C++).  The goal of this lab is to provide students with the foundations necessary to understand the dynamics of the adding and removing messages from a Linux Message Queue.

NB:  If you are not a CSPP student and are in need of a CS Cluster login ID (if you don't know what this is you are in need of one), contact the TAs immediately so you can get set up with a cluster login ID for the labs.  This course cannot be conducted without a CS Cluster login ID.  If you already have a UofC CNET ID, you can (and should) manually apply for a CS cluster ID here.


PRIMARY RESOURCES:

You should refer to relevant sections of the man pages for assistance for this lab, in addition to materials in the assigned chapters from the primary texts for this week (per the syllabus).

You should ssh into the cluster to perform all lab activities.

Make sure you have read this week's assigned reading. 

README

  1. If you are not in our course email list, please subscribe to the cspp51025 email list here:  http://mailman.cs.uchicago.edu/mailman/listinfo/cspp51025

  2. Turn the lab assignment as a tarball in by email to the TA (cc'ing the instructor) by the due date above.

  3. For printing out your documents, you might find the following commands useful during your year(s) in this department:

    1. lpr -  off line print. Note that this command is called when you print from acroread  (for .pdf files) or gv (for .ps files)
    2. lpq - shows the printer queue
    3. lprm - removes jobs from the printer queue
    4. enscript - converts text files to PostScript (useful when you want to print out text files)

  4. Make sure you have read the Submission Guidelines for submission.

LAB 7

In this lab we are going to crack passwords.  You have been given an MD5 hash of a 4 character password.  The valid characters used in this password are A-Z, a-z, and 0-9.   Four characters thus yield just under 15 million possibilities.  We are going to use a brute force and ignorance approach to finding this password.  In other words, we are going to try all possibilities.  A main controller thread is responsible for distributing work to an arbitrary number of worker threads (this value will be declared on the command line).  The main thread will supply each worker thread with the first two characters that worker thread is to use.  The worker thread will then permute over the remaining two characters using the available range above.

You must have coordination among these worker threads so that collisions do not occur.  One suggested solution might be to use an STL queue to store the unused first two-letter combinations.  When a worker thread completes it's work, it simply pops the next range off the queue.  The program ends when the password you hashed results in a hash that matches the hash provided.

See Mark Weindling's lecture for the text of the MD5 hash.

More information:

Spencer's Socket Site
Beej's Guide to Network Programming
Developerweb Unix Socket FAQ
Richard Steven's Home Page
BOOST Sockets
 

Mark Shacklette