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Tutorial B11 Breaking RSA

79 bytes added, 00:44, 16 July 2017
Finding SPA Leakage
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Run the SPA setup script.
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[[File:B11_SPAScript.png|400px]]
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Under the XXX tab, leave only the "Go Command", and delete the other commands. The RSA demo does not support sending a key, and instead will use the plaintext as a fake-key.
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[[File:B11_plaintext_setting.png|400px]]
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Change the CLKGEN to be CLKGEN x1 via DCM
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[[File:B11_clkgenx1.png|400px]]
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Change the length of the trigger to be 24000 samples:
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[[File:B11_settriglen.png|400px]]
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If you are using Capture V3.5.2 or later you will have support for the length of the trigger output being high reported back to you. If you run capture-1 for example you'll see the trigger was high for XX cycles:
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This is way too long! You won't be able to capture the entire trace in your 24000 length sample buffer. Instead we'll make the demo even shorter - in our case looking at the source code you can see there is a "flag" which is set high only AFTER the first 1 is received. Thus using a fixed plaintext, change the input plaintext to be all 00's (<code>00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</code>):
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[[File:B11_acqsetting.png|400px]]
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We'll only be able to change the LAST TWO bytes, everything else will be too slow. So change the input plaintext to
And you can see the power trace change drastically, as below:
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[[File:B11_RSA_example8000.png|600px]]
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Finally, let's flip another bit. Change the input plaintext as follows, such that bit #4 in the final bit is set HIGH. We can plot the two power traces on top of each other, and you see that they are differing at a specific point in time:
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[[File:B11_RSA_bit4diff.png|600px]]
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Walking back from the right, you can see this almost directly matches bit numbering for those last two bytes:
<br>[[File:B11_RSA_example8010_annotated.png|600px]]<br>
With a bit of setup done, we can now perform a few captures.
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