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Tutorial B8 Profiling Attacks (Manual Template Attack)

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Revision as of 12:16, 25 May 2016 by Gdeon (Talk | contribs) (Capturing the Traces: Added section)

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This tutorial is a more hands-on version of the previous tutorial. Rather than getting the ChipWhisperer Analyzer software to generate the points of interest and the template distributions, this tutorial will work directly with the recorded trace data in Python.

It is highly recommended that you read the theory page on Template Attacks before attempting this tutorial. There is some relatively complex processing involved, and it may be helpful to get a mathematical view on the steps before attempting to program them.

Additionally, this tutorial uses some terminology from previous tutorials, such as Hamming weight and substitution box. If you don't know what these are, Tutorial B6 Breaking AES (Manual CPA Attack) might be an easier starting point.

Capturing the Traces

As in the previous tutorial, this tutorial requires two sets of traces. The first set is a large number of traces (1000+) with random keys and plaintexts, assumed to come from your personal copy of the device. The second is a smaller number of traces (~50) with a fixed key and random plaintexts, assumed to come from the sensitive device that we're attacking. The goal of this tutorial is to recover the fixed key from the smaller set of traces.

The data collected from the previous tutorial will be fine for these steps. These examples will work with 2000 random-key traces and 50 fixed-key traces. If you don't have these datasets, follow the steps in Tutorial B7 Profiling Attacks (with HW Assumption) to record these traces.

Creating the Template

Steps to make the template

Mention Hamming weight assumption

Loading the Traces

Sorting the Traces

Points of Interest

Covariance Matrices

Performing the Attack

Steps to crack the code (tm)

Loading the Traces

Using the Template

Gotchas

  • Too little data (0 or 1 trace)
  • Flukes + statistics