AES-CCM Attack - Revision history

Coflynn at 21:45, 26 March 2017

2017-03-26T21:45:51Z

Coflynn: /* Bootloader Interface Code */

2017-03-25T18:02:39Z

‎Bootloader Interface Code

Coflynn at 18:01, 25 March 2017

2017-03-25T18:01:36Z

Coflynn at 18:01, 25 March 2017

2017-03-25T18:01:17Z

Coflynn at 16:44, 25 March 2017

2017-03-25T16:44:21Z

Coflynn at 14:11, 8 November 2016

2016-11-08T14:11:52Z

Coflynn: /* Collecting Traces */

2016-11-06T12:55:26Z

‎Collecting Traces

Coflynn: /* Breaking AES-CBC Encryption with unknown I.V. */

2016-11-06T12:53:54Z

‎Breaking AES-CBC Encryption with unknown I.V.

Coflynn: /* AES-CCM Overview */

2016-11-06T12:50:55Z

‎AES-CCM Overview

Coflynn at 12:50, 6 November 2016

2016-11-06T12:50:11Z

← Older revision		Revision as of 21:45, 26 March 2017
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	[[Category:Examples]]		[[Category:Examples]]
−	~~[[Category:Theory]]~~

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 == Bootloader Interface Code ==
-<syntaxhighlight>
+<syntaxhighlight lang="python">
 #!/usr/bin/python
 # -*- coding: utf-8 -*-

← Older revision		Revision as of 18:01, 25 March 2017
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	[[Category:Examples]]		[[Category:Examples]]
		+	[[Category:Theory]]

← Older revision		Revision as of 18:01, 25 March 2017
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	raise IOError("Failed to communicate, no response")		raise IOError("Failed to communicate, no response")
	</syntaxhighlight>		</syntaxhighlight>
		+
		+	[[Category:Examples]]

← Older revision		Revision as of 16:44, 25 March 2017
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−	{{~~Infobox~~\|WARNING: This page under construction!}}	+	{{Warningbox\|WARNING: This page under construction!}}

	The following is an overview of the AES-CMM attack done by Eyal Ronen et al., detailed in their draft/limited release paper [http://iotworm.eyalro.net/ IoT Goes Nuclear: Creating a ZigBee Chain Reaction (research paper website)], [http://eprint.iacr.org/2016/1047 IACR E-print submission]. If using this attack please '''do not cite this page''', instead cite the research paper only. The paper is currently a draft so there is no proceedings information etc as it has not yet been presented anywhere, but you can cite the E-Print version.		The following is an overview of the AES-CMM attack done by Eyal Ronen et al., detailed in their draft/limited release paper [http://iotworm.eyalro.net/ IoT Goes Nuclear: Creating a ZigBee Chain Reaction (research paper website)], [http://eprint.iacr.org/2016/1047 IACR E-print submission]. If using this attack please '''do not cite this page''', instead cite the research paper only. The paper is currently a draft so there is no proceedings information etc as it has not yet been presented anywhere, but you can cite the E-Print version.

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 {{Infobox|WARNING: This page under construction!}}
-The following is an overview of the AES-CMM attack done by Eyal Ronen et al., detailed in their draft/limited release paper [http://iotworm.eyalro.net/ IoT Goes Nuclear: Creating a ZigBee Chain Reaction]. If using this attack please '''do not cite this page''', instead cite the research paper only. The paper is currently a draft so there is no proceedings information etc as it has not yet been presented anywhere.
+The following is an overview of the AES-CMM attack done by Eyal Ronen et al., detailed in their draft/limited release paper [http://iotworm.eyalro.net/ IoT Goes Nuclear: Creating a ZigBee Chain Reaction (research paper website)], [http://eprint.iacr.org/2016/1047 IACR E-print submission]. If using this attack please '''do not cite this page''', instead cite the research paper only. The paper is currently a draft so there is no proceedings information etc as it has not yet been presented anywhere, but you can cite the E-Print version.
 This page is presented as an example of using Python/ChipWhisperer to perform attacks against the AES-CCM cipher, without needing to do a more complex attack against AES-CTR mode.

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 # Program into the target the aes-ccm bootloader. This bootloader can be found in the git repo, which also includes a .hex file.
 # Set the target type to the special AES-CCM bootloader driver. This target module is detailed in the appendix on this page, you can copy that code into a new file in the `target' directory.
-# Run a capture with ~500 traces.
+# Run a capture with ~500 traces. Use 1x CLKGEN for the ADC speed and the full point-range to be able to capture both software AES rounds. See capture script example for details.
 === Step #1: AES-CBC MAC Block #1 ===

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 If you've performed a standard CPA attack, you'll realize the problem with attacking AES-CBC is we don't directly control the input, which we call <math>PT</math>. Instead it's XORd with some unknown bytes (the AES-CBC ciphertext output).
-But if we are always attacking the same block (that is, we reset the AES state to initial by say resetting the device, and rerun the algorithm up to the first block), the unknown bytes are constant. As it turns out this is a pretty easy problem to solve. The first step is to perform a standard CPA attack. The only issue is we won't recover the actual encryption key used <math>k</math>, instead we recover <math>k \oplus CBC_{m-1} \oplus PT</math>, since we basically roll all the constant inputs into what we call a `modified key'. Note <math>CBC_{m-1}</math> is the output of the previous-block AES-CBC ciphertext.
+But if we are always attacking the same block (that is, we reset the AES state to initial by say resetting the device, and rerun the algorithm up to the first block), the unknown bytes are constant. As it turns out this is a pretty easy problem to solve. The first step is to perform a standard CPA attack. The only issue is we won't recover the actual encryption key used <math>k</math>, instead we recover <math>k \oplus CBC_{m-1}</math>, since we basically roll all the constant inputs into what we call a `modified key'. Note <math>CBC_{m-1}</math> is the output of the previous-block AES-CBC ciphertext.
 In what might seem like magic, we can use this modified key to directly determine the second-round key (the true key). This was originally presented by J. Jaffe in [https://www.iacr.org/archive/ches2007/47270001/47270001.pdf A First-Order DPA Attack Against AES in Counter Mode with Unknown Initial Counter]. The reason this works is if you remember we recovered  <math>k' = k \oplus CBC_{m-1}</math>. In the AES algorithm the first thing we do is the AddRoundKey, which is:

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 * Auth tag can be shortened (i.e., not full 16-byte length) for use with protocols with very sensitive length limitations.
- The difference between the two modes is explained below:
+The difference between the two modes is explained below:
 '''Cipher Block Chaining (CBC):''' The plaintext is XORed with the previous ciphertext before being encrypted. There is no ciphertext before the first plaintext, so a randomly chosen initialization vector (IV) is used instead: