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<p>
This tutorial can only be completed using the [[CW1200_ChipWhisperer-Pro]]. The ChipWhisperer software and its prerequisites should be installedand the [[CW1200_ChipWhisperer-Pro]] and hardware should be connected to each other and your computer. If not, this is the page for you: [[Installing ChipWhisperer]]. This tutorial is an extension of [[Tutorial B1 Building a SimpleSerial Project]] and [[Tutorial B5 Breaking AES (Straightforward)]], which should be completed first for better understanding.
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Save this code, and then find the <code>makefile</code> file and open it in a text editor of your choice. Find this piece of code near the top:
<pre>
# Target file name (without extension).
# This is the base name of the compiled .hex file.
TARGET = simpleserial-aes
# List C source files here.
# Header files (.h) are automatically pulled in.
SRC += simpleserial-aes.c
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Change the <code>TARGET = simpleserial-aes</code> line to <code>TARGET = simpleserial-aes-stream</code> and the <code>SRC += simpleserial-aes.c</code> line to <code>SRC += simpleserial-aes-stream.c</code>
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Open your command line in the <code>simpleserial-aes-stream</code> directory and run the <code>make</code> command for the correct target. For example: for the XMEGA run <code>make PLATFORM=CW303</code>. This will create a <code>.hex</code> file in the same directory. This step requires avr-gcc to be set-up and added to your system path. If you have not done this go back to [[Installing ChipWhisperer]] under the <b>Required Tools</b> dropdown.
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Next open the ChipWhisperer software. Hopefully you know how to do this by now.
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Run the <code>Project>Example Scripts>ChipWhisperer-Lite: AES SimpleSerial on XMEGA</code> script. We will modify some of the settings.
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The modifications to the settings will allow us the use stream mode while manually sending a plain text for encryption. We will then look at the stream data and identify where the encryption takes place and what it looks like.
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Under the <b>Scope Settings</b> find the <b>ADC Clock</b> section. Here change the <b>Source</b> setting to <code>CLKGEN x1 via DCM</code>. The <b>ADC Sample Rate</b> field should auto-populate to <b>7.3846 MS/s</b> or a number approximately equal. If the sampling rate is above 10 MS/s the streaming mode will not work as the buffer in the FPGA will overflow.
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[[File:ADC Clock.PNG]]
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Under the <b>Scope Settings</b> find the <b>Trigger Setup</b> section. Enable <b>Stream Mode</b>. The <b>Mode</b> field needs to be set to <code>low</code> so the sample capture starts right away because the target does not set the trigger line to high anymore during encryption.
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Under the same section change the <b>Total Samples</b> field to <code>11000000</code>. This will give use a window of approximately 1.5 seconds to send a plain text and capture the power measurements during encryption.
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Note: The <b>Timeout (secs)</b> field needs to be set greater than the time it needs to stream the samples and a little additional time to allow for hardware communication. For example: 11 million samples take about 1.5 seconds at the sampling rate of 7.3MS/s so this field should be set to <code>2</code> seconds. You can set it higher if needed.
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