Changes

Note that unlike the previous attack, we will require ''two'' acquisition campaigns. We must first create a template, which means we'll need a system which we control (or at least know the key for). In real life this would typically mean using another copy of the protected device; e.g. you have a protected device, but you buy another copy which you control. We use the copy we control to characterize the leakage, before applying what we have learned onto the real device with an unknown key.

== Setting up the Hardware and Software ==

== Capturing the Traces ==

<li>Change the number of traces to be ''1000'': more traces are needed to form the profile. In this case 1000 is a very small capture, however for this unprotected implementation will be sufficient. An interesting experiment is to see how using more or less traces impacts your templates!</li>

<li>Hit the ''Capture Many'' button (M in a green triangle) to start the capture process. You will see each new trace plotted in the waveform display. Once the capture is complete, save the project file again.</li>

=== Capturing the Attack Traces ===

# Save the project now in the same directory as the <code>.cwp</code> file from the previous section, giving it a name indicating the key is '''fixed''' and text is '''random'''. For example you could call it <code>tut_fixedkey_randplain.cwp</code>, again saving it in the same directory as the previous file.

# Change the number of traces to be ''20'': by comparison the profiling attack will require less attack traces compared to the CPA attack.

# Hit the ''Capture Many'' button (M in a green triangle) to start the capture process. You will see each new trace plotted in the waveform display. Once the capture is complete, save the project file again.

== Generating the Template ==

<li>Open the Analyzer software</li>

<li>From the ''File --&gt; Open Project'' option, navigate to the <code>tut_randkey_randplain.cwp</code> file you save previously. Open this file, ensure it is the file corresponding with the '''randomly changing encryption key'''!</li>

<p>[[File:traceexplorer1.png|image]]</p></li>

<li><p>Hit the ''Display'' button, and then select ''All On''. This displays the differences between the various groups of Hamming Weight (HW) values:</p>

</blockquote>

<ol start="7" style="list-style-type: decimal;">

<li><p>Change the attack module to ''Profiling'':</p>

<p>[[File:selectprofiling.png|image]]</p></li>

<p>[[File:templategeneration.png|image]]</p></li>

<li>Click the ''Generate Templates'' button. This will dynamically load and run the <code>def generateTemplates(self):</code> function in the scripting window.</li>

partitiontype = PartitionHWIntermediate

filename = avr_keyrand_plainrand_1000traces_data\analysis\templates-PartitionHWIntermediate-0-999.npz</pre></li>

== Applying the Template ==

<ol style="list-style-type: decimal;">

<li>From the ''File --&gt; Open Project'' option, navigate to the <code>tut_fixedkey_randplain.cwp</code> file you save previously. Open this file, ensure it is the file corresponding with the '''fixed encryption key'''!</li>

<li>Open the project text editor if not already open.</li>

<li><p>Append the ''Template Data'' section you copied from the previous project to your project file:</p>

<p>[[File:projecteditor_addtemplate.png|image]]</p></li>

<li><p>Change the attack module to ''Profiling'':</p>

<p>[[File:selectprofiling.png|image]]</p></li>

<li><p>Press the ''Attack'' button. Observe that with only a few traces you are able to determine the encryption key:</p>

<p>[[File:attack_working.png|image]]</p></li></ol>