Setting up for the Lab

• We will need some tools, so let's install those first.
  1. Boot your image and log in as bob.
  2. Perform the following
     • sudo apt update
     • sudo apt install git
     • sudo apt install bless
• Set up to work
  1. Create a directory where we will work
     • Make sure you are in your home directory
       • cd
     • create a working directory : md5collision
       • mkdir md5collision
       • cd md5collision
  2. Download and compile md5collgen
     • zhijieshi maintains a easy to compile version
     • Download this with git clone https://github.com/zhijieshi/md5collgen.git
     • This will create a directory called md5collgen
     • Change to that directory cd md5collgen
     • The code uses some features from c++17 and beyond, but we can adjust to this.
     • Download this main.cpp file into the md5collgen directory.
       • use wget https://mirkwood.cs.edinboro.edu/~bennett/class/cmac2000/labs/md5coll/main.cpp
       • If you are working on a computer with a newer compiler, you can skip this step.
     • compile this by typing make
  3. Test md5collgen
     • Move up one directory cd ..
     • Create a file called header, put some text into it.
     • md5collgen/md5collgen -p header -o out1 out2
     • md5sum out1
     • md5sum out2
     • diff out1 out2
     • Edit the files with bless, the hex editor
       • bless out1
       • start a second window, change to this directory
         • cd md5collision
         • bless out2
       • Compare the different blocks.
• Bless
  • supports multiple tables, but seems to crash sometimes when using multiple tabs. I just use one instance of bless.
  • Spend a little time to explore bless, we will be using it throughout the labl.