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Tutorial A5 Breaking AES-256 Bootloader

37,157 bytes removed, 13:34, 29 July 2019
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'''''THIS TUTORIAL IS INCOMPLETE AND STILL BEING UPDATED'''''{{Warningbox|This tutorial has been updated for ChipWhisperer 5 release. If you are using 4.x.x or 3.x.x see the "V4" or "V3" link in the sidebar.}}
This {{Infobox tutorial will take you through a complete attack on an encrypted bootloader using |name = A5: Breaking AES-256. This demonstrates how to using sideBootloader|image = |caption = |software versions =|capture hardware = CW-channel power analysis on practical systemsLite, along with discussing how to perform custom scripts along with custom analysis scripts.CW-Lite 2-Part, CW-Pro|Target Device = |Target Architecture = XMEGA/Arm|Hardware Crypto = No|Purchase Hardware = }}
Whilst the tutorial assumes you will be performing the entire capture of traces along with the attack<!-- To edit this, it is possible to download the traces if you don't have the hardware, in which case skip section [[#Setting up the Hardware]] and [[#Capturing the Traces]].edit Template:Tutorial_boilerplate -->{{Tutorial boilerplate}}
= Background =In the world of microcontrollers, a bootloader is a special piece of firmware that is made to let the user upload new programs into memory. This is especially useful for devices with complex code that may need to be patched or otherwise updated in the future * Jupyter file: '''PA_Multi_1- a bootloader makes it possible for the user to upload a patched version of the firmware onto the micro. The bootloader receives information from a communication line (a USB port, serial port, ethernet port, WiFi connection, etc...) and stores this data into program memory. Once the full firmware has been received, the micro can happily run its updated codeBreaking_AES-256_Bootloader.ipynb'''
There is one big security issue to worry about with bootloaders. A company may want to stop their customers from writing their own firmware and uploading it onto the micro. For example, this might be for protection reasons - hackers might be able to access parts of the device that weren't meant to be accessed. One way of stopping this is to add encryption. The company can add their own secret signature to the firmware code and encrypt it with a secret key. Then, the bootloader can decrypt the incoming firmware and confirm that the incoming firmware is correctly signed. Users will not know the secret key or the signature tied to the firmware, so they won't be able to "fake" their own.
This tutorial will work with a simple AES-256 bootloader. The victim will receive data through a serial connection, decrypt the command, and confirm that the included signature is correct. Then, it will only save the code into memory if the signature check succeeded. To make this system more robust against attacks, the bootloader will use cipher-block chaining (CBC mode). Our goal is to find the secret key and the CBC initialization vector so that we could successfully fake our own firmware.== XMEGA Target ==
== Bootloader Communications Protocol ==The bootloader's communications protocol operates over a serial port at 38400 baud rate. The bootloader is always waiting for new data to be sent in this example; in real life one would typically force See the bootloader to enter through a command sequence.following for using:* ChipWhisperer-Lite Classic (XMEGA)* ChipWhisperer-Lite Capture + XMEGA Target on UFO Board (including NAE-SCAPACK-L1/L2 users)* ChipWhisperer-Pro + XMEGA Target on UFO Board
Commands sent to the bootloader look as followshttps://chipwhisperer.readthedocs.io/en/latest/tutorials/pa_multi_1-openadc-cwlitexmega.html#tutorial-pa-multi-1-openadc-cwlitexmega
<pre> |<== ChipWhisperer-------- Encrypted block (16 bytes) ---------->| | |+------+------+------+------+------+------+ .... +------+------+------+| 0x00 | Signature (4 Bytes) | Data (12 Bytes) | CRC-16 |+------+------+------+------+------+------+ .... +------+------+------+<Lite ARM /pre>STM32F3 Target ==
This frame has four partsSee the following for using:* <code>0x00</code>: 1 byte of fixed header* Signature: A secret 4 byte constant. The bootloader will confirm that this signature is correct after decrypting the frame.* Data: 12 bytes of the incoming firmware. This system forces us to send the code 12 bytes at a time; more complete bootloaders may allow longer variableChipWhisperer-length frames.Lite 32-bit (STM32F3 Target)* CRCChipWhisperer-16: A 16Lite Capture + STM32F3 Target on UFO Board (including NAE-bit checksum using the CRCSCAPACK-CCITT polynomial (0x1021L1/L2 users). The LSB of the CRC is sent first, followed by the MSB. The bootloader will reply over the serial port, describing whether or not this CRC check was valid.As described in the diagram, the 16 byte block is not sent as plaintext. Instead, it is encrypted using AES* ChipWhisperer-256 in CBC mode. This encryption method will be described in the next section.Pro + STM32F3 Target on UFO Board
The bootloader responds to each command with a single byte indicating if the CRC-16 was OK or nothttps://chipwhisperer.readthedocs.io/en/latest/tutorials/pa_multi_1-openadc-cwlitearm.html#tutorial-pa-multi-1-openadc-cwlitearm
<pre> +------+CRC-OK: | 0xA1 | +------+== ChipWhisperer Nano Target ==
+------+CRC Failed: | 0xA4 | +------+</pre> Then, after replying to the command, the bootloader veries that the signature is correct. If it matches the expected manufacturer's signature, the 12 bytes of data will be written to flash memory. Otherwise, the data is discarded. == Details of AES-256 CBC == The system uses the AES algorithm in Cipher Block Chaining (CBC) mode. In general one avoids using encryption 'as-is' (i.e. Electronic Code Book), since it means any piece of plaintext always maps to the same piece of ciphertext. Cipher Block Chaining ensures that if you encrypted the same thing a bunch of times it would always encrypt to a new piece of ciphertext. You can see another reference on the design of the encryption side; we'll be only talking about the decryption side here. In this case AES-256 CBC mode is used as follows, where the details of the AES-256 Decryption block will be discussed in detail later: [[File:aes256_cbc.png|image]] This diagram shows that the output of the decryption is no longer used directly as the plaintext. Instead, the output is XORed with a 16 byte mask, which is usually taken from the previous ciphertext. Also, the first decryption block has no previous ciphertext to use, so a secret initialization vector (IV) is used instead. If we are going to decrypt the entire ciphertext (including block 0) or correctly generate our own ciphertext, we'll need to find this IV along with the AES key.  == Attacking AES-256 ==The system in this tutorial uses AES-256 encryption, which has a 256 bit (32 byte) key - twice as large as the 16 byte key we've attacked in previous tutorials. This means that our regular AES-128 CPA attacks won't quite work. However, extending these attacks to AES-256 is fairly straightforward: the theory is explained in detail in [[Extending AES-128 Attacks to AES-256]].  As the theory page explains, our AES-256 attack will have 4 steps:# Perform a standard attack (as in AES-128 decryption) to determine the first 16 bytes of the key, corresponding to the 14th round encryption key.# Using the known 14th round key, calculate the hypothetical outputs of each S-Box from the 13th round using the ciphertext processed by the 14th round, and determine the 16 bytes of the 13th round key manipulated by inverse MixColumns.# Perform the MixColumns and ShiftRows operation on the hypothetical key determined above, recovering the 13th round key.# Using the AES-256 key schedule, reverse the 13th and 14th round keys to determine the original AES-256 encryption key. = Setting up the Hardware =This tutorial uses the [[CW1173 ChipWhisperer-Lite]] hardware. This hardware does not require any special setup - it should be ready to go out-of-the-box. Note that you '''don't need hardware''' to complete the tutorial. Instead, you can download [https://www.assembla.com/spaces/chipwhisperer/wiki/Example_Captures example traces from the ChipWhisperer Site]. Just look available for the traces titled ''AVR: AES256 Bootloader (ChipWhisperer Tutorial #A5)''. == Building/Programming the Bootloader == TODO. Notes to self:* Make sure bootloader code is in repo* Makefile* Describe code (aes, bootloader, supersecret) = Capturing the Traces =Once the hardware is ready, we can capture some traces for our attack using the ChipWhisperer Capture software. If you somehow got to the 5th ''Advanced Tutorial'' without getting this software ready, you can follow the helpful guide at [[Installing ChipWhisperer]]. In some of the previous tutorials, we entered all of the capture settings by hand. Since we are civilized humans armed with technology, we can use a script to do all of this setup for us. A pre-written Python script is provided at [[#Appendix A: Capture Script]]. Take a look at this code and notice what it does:* it fills in the scope, target, and trace format that we'll use;* it connects to the hardware; and* it loads all of the hardware parameters for us. Nice!Copy this script into a <code>.py</code> file somewhere convenient. Then, perform the following steps to finish the capture:# Run the capture script, which will open a ChipWhisperer Capture window with everything connected for us.# Open the terminal (''Tools > Terminal'') and connect to the board. While the terminal is open, press the ''Capture 1'' button. A single byte of data should appear in the terminal. This byte will either be <code>a1</code> (CRC failed) or <code>a4</code> (CRC OK). If you see any other responses, something is wrong. #: [[File:Tutorial-A5-Capture.PNG|image]]# Once you're happy with this, open the General Settings tab and set the Number of Traces. You should need around 100 traces to break AES.# Press the ''Capture Many'' button to record the 100 traces. You'll see the new traces plotted on-screen.# Once the program is finished capturing the traces, save the project. Put it somewhere memorable and give it a nice name. = Finding the Encryption Key =Now that we have our traces, we can go ahead and perform the attack. As described in the background theory, we'll have to do two attacks - one to get the 14th round key, and another (using the first result) to get the 13th round key. Then, we'll do some post-processing to finally get the 256 bit encryption key. == 14th Round Key == <ol style="list-style-type: decimal;"><li>Open the Analyzer software</li><li>From the ''File --&gt; Open Project'' option, navigate to the .cwp file containing the 13th and 14th round power usage. This can be either the aes256_round1413_key0_100.cwp file downloaded, or the capture you performed.</li><li><p>If you wish to view the trace data, follow these steps:</p><ol style="list-style-type: decimal;"><li>Switch to the ''Waveform Display'' tab</li><li>Switch to the ''General'' parameter setting tab</li><li>You can choose to plot a specific range of traces</li><li>Hit the ''Redraw'' button when you change the trace plot range</li><li>You can right-click on the waveform to change options, or left-click and drag to zoom</li><li>Use the toolbar to quickly reset the zoom back to original</li></ol> <p>[[File:traceplottinground13.png|image]]</p></li><li><p>You can view or change the attack options on the ''Attack'' parameter settings tab:</p><ol style="list-style-type: decimal;"><li>On the ''Hardware Model'' settings, ensure you select ''Decryption''</li><li>The ''Point Setup'' makes the attack faster by looking over a more narrow range of points. Often you might have to characterize your device to determine the location of specific attack points of interest, although you can use the range of 2900 to 4200 here for a faster attack. The default range of all the points will work fine too!</li></ol> <p>[[File:attacksettingsround13.png|image]]</p></li><li>The saved traces ''do not'' have the known encryption key stored in them. If you want to have the correct encryption key highlighted in red, switch to the ''Results'' tab and set the override key as <code>ea 79 79 20 c8 71 44 7d 46 62 5f 51 85 c1 3b cb</code>.</li><li><p>Finally run the attack by switching to the ''Results Table'' tab and then hitting the ''Attack'' button:</p><p>[[File:aes14roundstartattack.png|image]]</p></li><li><p>If you adjusted the ''Reporting Interval'' to a smaller number such as 5, you'll see the progression of attack results as more traces are used. If you have enabled the GUI override you should see the correct bytes highlighted in red, as below:</p><p>[[File:aes14table_highlight.png|image]]</p><p>If you haven't enabled the GUI override, the wrong bytes are highlighted (since it uses some other default key). However the most likely bytes as a result of the attack are still the top bytes, the red highlighting is purely decorative. Notice the large jump in correlation between the correct guess and wrong guess:</p><p>[[File:aes14table_nohighlight.png|image]]</p></li><li><p>You can also switch to the ''Output vs Point Plot'' window to see ''where'' exactly the data was recovered:</p><ol style="list-style-type: decimal;"><li>Switch to the ''Output vs Point Plot'' tab</li><li>Turn on one of the bytes to see results.</li><li>The ''known correct'' guess for the key is highlighted in red. If you did not enable the 'override' feature the wrong bytes are highlighted, as the system does not know the correct key. By viewing the spikes you can see where the attack succeeded.</li></ol> <p>[[File:aes14round_points.png|image]]</p></li></ol> == 13th Round Key == Attacking the 13th round key requires the use of a script. We cannot configure the system through the GUI, as we have no built-in model for the second part of the AES-256 algorithm. This will demonstrate how we can insert custom models into the system. See [[#Appendix B AES-256 14th Round Key Script]] for complete script used here. Remember that when you change settings in the GUI, the system is actually just automatically adjusting the attack script. You could modify the attack script directly instead of changing GUI settings. Every time you touch the GUI the autogenerated script is overwritten however, so it would be easy to lose your changes. As an example here is how setting the point range maps to an API call: <blockquote>[[File:autoscript1.png|image]]</blockquote>We will first automatically configure a script, and then use that as the base for our full attack. <ol style="list-style-type: decimal;"><li>Open the Analyzer software</li><li>From the ''File --&gt; Open Project'' option, navigate to the .cwp file containing the 13th and 14th round power usage. This can be either the aes256_round1413_key0_100.cwp file downloaded, or the capture you performed.</li><li><p>View the trace data as before, and notice how the data becomes unsynchronized. This is due to the prescense of a non-constant AES implementation. There is actually a timing attack in this AES implementation, but we ignore that for now!</p><p>[[File:syncproblems.png|image]]</p></li><li>Enable the ''Resync: Sum of Difference'' module:</li></ol> <blockquote>[[File:resyncsad.png|image]]</blockquote><ol start="5" style="list-style-type: decimal;"><li>Configure the reference points to (9063, 9177) and the input window to (9010, 9080):</li></ol> <blockquote>[[File:resyncsad2.png|image]]</blockquote><ol start="6" style="list-style-type: decimal;"><li>Redraw the traces, confirm we now have synchronization on the second half:</li></ol> <blockquote>[[File:resyncsad3.png|image]]</blockquote><ol start="7" style="list-style-type: decimal;"><li>We will again set the AES mode to ''Decryption''. Under the ''Attack'' tab on the ''Hardware Model'' settings, ensure you select ''Decryption''</li><li><p>We are now ready to insert the custom data into the attack module. On the ''General'' tab, make a copy of the auto-generated script. Do so by clicking on the autogenerated row, hit ''Copy'', save the file somewhere. Double-click on the description of the new file and give it a better name. Finally hit ''Set Active'' after clicking on your new file. The result should look like this:</p><p>[[File:aes256_customscript.png|image]]</p></li><li>You can now edit the custom script file using the built-in editor OR with an external editor. In this example the file would be <code>C:\Users\Colin\AppData\Local\Temp\testaes256.py</code>.</li></ol> The following defines the required functions for our AES-256 attack on the 2nd part of the decryption key (i.e. the 13th round key): <pre># Imports for AES256 Attackfrom chipwhisperer.analyzer.attacks.models.AES128_8bit import getHWfrom chipwhisperer.analyzer.models.aes.funcs import sbox, inv_sbox, inv_shiftrows, inv_mixcolumns, inv_subbytes class AES256Attack(object): numSubKeys = 16  @staticmethod def leakage(textin, textout, guess, bnum, setting, state): if setting == 13: knownkey = [0xea, 0x79, 0x79, 0x20, 0xc8, 0x71, 0x44, 0x7d, 0x46, 0x62, 0x5f, 0x51, 0x85, 0xc1, 0x3b, 0xcb] xored = [knownkey[i] ^ textin[i] for i in range(0, 16)] block = xored block = inv_shiftrows(block) block = inv_subbytes(block) block = inv_mixcolumns(block) block = inv_shiftrows(block) result = block return getHW(inv_sbox((result[bnum] ^ guess)))</pre>You can look back at the C code of the AES-256 decryption to see how this is implementing the decryption code. Note that because of the Inverse MixCols operation, we need the entire input ciphertext, and cannot use just a single byte of the input ciphertext. <ol start="10" style="list-style-type: decimal;"><li>Add the above function to your custom script file.</li><li><p>Change the <code>setAnalysisAlgorithm</code> to use your custom functions byt making the following call:</p><pre>self.attack.setAnalysisAlgorithm(CPAProgressive, AES256Attack, 13)</pre></li><li><p>Check you have set the attack direction to decryption, and you can reduce the point range to speed up your attack. Simply ensure you have the following lines in the script:</p><pre>#... some more lines ...self.attack.setDirection('dec')#... some more lines ...self.attack.setPointRange((8000,10990))#... some more lines ...</pre></li><li>Note you can check [[#Appendix C AES-256 13th Round Key Script]] for the complete contents of that file, and just copy/paste the complete contents.</li><li><p>Run ''Start Attack'' as before! Wait for the attack to complete, and you will determine the 13th round key:</p><p>[[File:aes13roundresults.png|image]]</p></li></ol> Remember the key we determined was actually the key passed through inverse mixcols and inverse shiftrows. This means we need to pass the key through shiftrows and mixcols to remove the effect of those two functions, and determine the normal 13th round key. This can be done via the interactive Python console: <pre>&gt;&gt;&gt; from chipwhisperer.analyzer.models.aes.funcs import shiftrows,mixcolumns&gt;&gt;&gt; knownkey = [0xC6, 0xBD, 0x4E, 0x50, 0xAB, 0xCA, 0x75, 0x77, 0x79, 0x87, 0x96, 0xCA, 0x1C, 0x7F, 0xC5, 0x82]&gt;&gt;&gt; key = shiftrows(knownkey)&gt;&gt;&gt; key = mixcolumns(key)&gt;&gt;&gt; print &quot; &quot;.join([&quot;%02x&quot; % i for i in key])c6 6a a6 12 4a ba 4d 04 4a 22 03 54 5b 28 0e 63</pre>At this point we have the 13th round key: <code>c6 6a a6 12 4a ba 4d 04 4a 22 03 54 5b 28 0e 63</code> == Recovering the Encryption Key == If you remember that AES decryption is just AES encryption performed in reverse, this means the two keys we recovered are the 13th and 14th round encryption keys. AES keys are given as an 'initial' key which is expanded to all round keys. In the case of AES-256 this initial key is directly used by the initial setup and 1st round of the algorithm. For this reason the initial key is referred to as the ''0/1 Round Key'' in this tutorial, and the key we've found is the ''13/14 Round Key''. Writing out the key we do know gives us this: <pre>c6 6a a6 12 4a ba 4d 04 4a 22 03 54 5b 28 0e 63 ea 79 79 20 c8 71 44 7d 46 62 5f 51 85 c1 3b cb</pre>You can use the the AES key scheduling tool built into ChipWhisperer to reverse this key: [[File:keyschedule_tool.png|image]] The tool is accessible from the ''Tools'' menu. Copy and paste the 32-byte known key into the input text line. Tell the tool this is the 13/14 round key, and it will automatically display the complete key schedule along with the initial encryption key. You should find the initial encryption key is: <pre>94 28 5d 4d 6d cf ec 08 d8 ac dd f6 be 25 a4 99 c4 d9 d0 1e c3 40 7e d7 d5 28 d4 09 e9 f0 88 a1</pre> = Analysis of Encrypted Files = TODO = Analysis of Power Traces for IV = TODO Example: <pre>#Imports for IV Attackfrom Crypto.Cipher import AES def initPreprocessing(self): self.preProcessingResyncSAD0 = preprocessing.ResyncSAD.ResyncSAD(self.parent) self.preProcessingResyncSAD0.setEnabled(True) self.preProcessingResyncSAD0.setReference(rtraceno=0, refpoints=(6300,6800), inputwindow=(6000,7200)) self.preProcessingResyncSAD1 = preprocessing.ResyncSAD.ResyncSAD(self.parent) self.preProcessingResyncSAD1.setEnabled(True) self.preProcessingResyncSAD1.setReference(rtraceno=0, refpoints=(4800,5100), inputwindow=(4700,5200)) self.preProcessingList = [self.preProcessingResyncSAD0,self.preProcessingResyncSAD1,] return self.preProcessingList class AESIVAttack(object): numSubKeys = 16  @staticmethod def leakage(textin, textout, guess, bnum, setting, state): knownkey = [0x94, 0x28, 0x5D, 0x4D, 0x6D, 0xCF, 0xEC, 0x08, 0xD8, 0xAC, 0xDD, 0xF6, 0xBE, 0x25, 0xA4, 0x99, 0xC4, 0xD9, 0xD0, 0x1E, 0xC3, 0x40, 0x7E, 0xD7, 0xD5, 0x28, 0xD4, 0x09, 0xE9, 0xF0, 0x88, 0xA1] knownkey = str(bytearray(knownkey)) ct = str(bytearray(textin))  aes = AES.new(knownkey, AES.MODE_ECB) pt = aes.decrypt(ct) return getHW(bytearray(pt)[bnum] ^ guess)</pre>= Timing Attacks for Signature = = Appendix A: Capture Script = The following: <pre>#!/usr/bin/python# -*- coding: utf-8 -*-## Copyright (c) 2013-2014, NewAE Technology Inc# All rights reserved.## Authors: Colin O'Flynn## Find this and more at newae.com - this file is part of the chipwhisperer# project, http://www.assembla.com/spaces/chipwhisperer## This file is part of chipwhisperer.## chipwhisperer is free software: you can redistribute it and/or modify# it under the terms of the GNU General Public License as published by# the Free Software Foundation, either version 3 of the License, or# (at your option) any later version.## chipwhisperer is distributed in the hope that it will be useful,# but WITHOUT ANY WARRANTY; without even the implied warranty of# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the# GNU Lesser General Public License for more details.## You should have received a copy of the GNU General Public License# along with chipwhisperer. If not, see &lt;http://www.gnu.org/licenses/&gt;.#=================================================#### This example captures data using the ChipWhisperer Rev2 capture hardware.# The target is a SimpleSerial board attached to the ChipWhisperer.## Data is saved into both a project file and a MATLAB array# #Setup pathimport sys import time #Import the ChipWhispererCapture moduleimport chipwhisperer.capture.ChipWhispererCapture as cwcfrom chipwhisperer.capture.targets.TargetTemplate import TargetTemplatefrom chipwhisperer.capture.targets.SimpleSerial import SimpleSerial_ChipWhisperer #Check for PySidetry: from PySide.QtCore import * from PySide.QtGui import *except ImportError: print &quot;ERROR: PySide is required for this program&quot; sys.exit() import thread import scipy.io as sio exitWhenDone=False def pe(): QCoreApplication.processEvents() # Class Crc############################################################## These CRC routines are copy-pasted from pycrc, which are:# Copyright (c) 2006-2013 Thomas Pircher &lt;tehpeh@gmx.net&gt;#class Crc(object): &quot;&quot;&quot; A base class for CRC routines. &quot;&quot;&quot;  def __init__(self, width, poly): &quot;&quot;&quot;The Crc constructor.  The parameters are as follows: width poly reflect_in xor_in reflect_out xor_out &quot;&quot;&quot; self.Width = width self.Poly = poly   self.MSB_Mask = 0x1 &lt;&lt; (self.Width - 1) self.Mask = ((self.MSB_Mask - 1) &lt;&lt; 1) | 1  self.XorIn = 0x0000 self.XorOut = 0x0000  self.DirectInit = self.XorIn self.NonDirectInit = self.__get_nondirect_init(self.XorIn) if self.Width &lt; 8: self.CrcShift = 8 - self.Width else: self.CrcShift = 0  def __get_nondirect_init(self, init): &quot;&quot;&quot; return the non-direct init if the direct algorithm has been selected. &quot;&quot;&quot; crc = init for i in range(self.Width): bit = crc &amp; 0x01 if bit: crc ^= self.Poly crc &gt;&gt;= 1 if bit: crc |= self.MSB_Mask return crc &amp; self.Mask   def bit_by_bit(self, in_data): &quot;&quot;&quot; Classic simple and slow CRC implementation. This function iterates bit by bit over the augmented input message and returns the calculated CRC value at the end. &quot;&quot;&quot; # If the input data is a string, convert to bytes. if isinstance(in_data, str): in_data = [ord(c) for c in in_data]  register = self.NonDirectInit for octet in in_data: for i in range(8): topbit = register &amp; self.MSB_Mask register = ((register &lt;&lt; 1) &amp; self.Mask) | ((octet &gt;&gt; (7 - i)) &amp; 0x01) if topbit: register ^= self.Poly  for i in range(self.Width): topbit = register &amp; self.MSB_Mask register = ((register &lt;&lt; 1) &amp; self.Mask) if topbit: register ^= self.Poly  return register ^ self.XorOut class BootloaderTarget(TargetTemplate): paramListUpdated = Signal(list)  def setupParameters(self): self.ser = SimpleSerial_ChipWhisperer() self.keylength = 16 self.input = &quot;&quot; self.crc = Crc(width=16, poly=0x1021)  def setOpenADC(self, oadc): try: self.ser.setOpenADC(oadc) except: pass  def setKeyLen(self, klen): &quot;&quot;&quot; Set key length in BITS &quot;&quot;&quot; self.keylength = klen / 8  def keyLen(self): &quot;&quot;&quot; Return key length in BYTES &quot;&quot;&quot; return self.keylength   def paramList(self): return []  def con(self): self.ser.con() self.ser.flush()  def dis(self): self.close()  def close(self): if self.ser != None: self.ser.close() self.ser = None return  def init(self): pass  def setModeEncrypt(self): return  def setModeDecrypt(self): return  def loadEncryptionKey(self, key): pass  def loadInput(self, inputtext): self.input = inputtext  def isDone(self): return True  def readOutput(self): #No actual output return [0] * 16  def go(self): # Starting byte is 0x00 message = [0x00]  # Append 16 bytes of data message.extend(self.input)  # Append 2 bytes of CRC for input only (not including 0x00) crcdata = self.crc.bit_by_bit(self.input)  message.append(crcdata &gt;&gt; 8) message.append(crcdata &amp; 0xff)  # Write message for i in range(0, 5): self.ser.flush() self.ser.write(message) time.sleep(0.1) data = self.ser.read(1)  if len(data) &gt; 0: resp = ord(data[0])  if resp == 0xA4: # Encryption run OK break  if resp != 0xA1: raise IOError(&quot;Bad Response %x&quot; % resp)  if len(data) &gt; 0: if resp != 0xA4: raise IOError(&quot;Failed to communicate, last response: %x&quot; % resp) else: raise IOError(&quot;Failed to communicate, no response&quot;)  def checkEncryptionKey(self, kin): return kin class userScript(QObject):  def __init__(self, capture): super(userScript, self).__init__() self.capture = capture   def run(self): cap = self.capture  #User commands here print &quot;***** Starting User Script *****&quot;  tbootloader = BootloaderTarget()  cap.setParameter(['Generic Settings', 'Scope Module', 'ChipWhisperer/OpenADC']) cap.setParameter(['Generic Settings', 'Trace Format', 'ChipWhisperer/Native'])  cap.target.setDriver(tbootloader)  #Load FW (must be configured in GUI first) cap.FWLoaderGo()  #NOTE: You MUST add this call to pe() to process events. This is done automatically #for setParameter() calls, but everything else REQUIRES this pe()  cap.doConDis()  pe()  #Example of using a list to set parameters. Slightly easier to copy/paste in this format lstexample = [['CW Extra', 'CW Extra Settings', 'Trigger Pins', 'Front Panel A', False], ['CW Extra', 'CW Extra Settings', 'Trigger Pins', 'Target IO4 (Trigger Line)', True], ['CW Extra', 'CW Extra Settings', 'Clock Source', 'Target IO-IN'], ['OpenADC', 'Clock Setup', 'ADC Clock', 'Source', 'EXTCLK x4 via DCM'], ['OpenADC', 'Trigger Setup', 'Total Samples', 11000], ['OpenADC', 'Trigger Setup', 'Offset', 0], ['OpenADC', 'Gain Setting', 'Setting', 45], ['OpenADC', 'Trigger Setup', 'Mode', 'rising edge'], #Final step: make DCMs relock in case they are lost ['OpenADC', 'Clock Setup', 'ADC Clock', 'Reset ADC DCM', None],  ['Generic Settings', 'Auxilary Module', 'Toggle FPGA-GPIO Pins'], ['GPIO Toggle', 'Standby State', 'High'], ['GPIO Toggle', 'Post-Toggle Delay', 150], ['GPIO Toggle', 'Toggle Length', 100], ]  # For IV: offset = 70000  #Download all hardware setup parameters for cmd in lstexample: cap.setParameter(cmd)  #Let's only do a few traces cap.setParameter(['Generic Settings', 'Acquisition Settings', 'Number of Traces', 50])  #Throw away first few cap.capture1() pe() cap.capture1() pe()  print &quot;***** Ending User Script *****&quot;  if __name__ == '__main__': #Make the application app = cwc.makeApplication()  #If you DO NOT want to overwrite/use settings from the GUI version including #the recent files list, uncomment the following: #app.setApplicationName(&quot;Capture V2 Scripted&quot;)  #Get main module capture = cwc.ChipWhispererCapture()  #Show window - even if not used capture.show()  #NB: Must call processEvents since we aren't using proper event loop pe() # Call user-specific commands usercommands = userScript(capture)  usercommands.run()  app.exec_()  sys.exit()</pre> = Appendix B AES-256 14th Round Key Script = '''NB: This script works for 0.10 release or later, see local copy in doc/html directory of chipwhisperer release if you need earlier versions''' Full attack script, copy/paste into a file then add as active attack script: <pre># AES-256 14th Round Key Attackfrom chipwhisperer.common.autoscript import AutoScriptBase#Imports from Preprocessingimport chipwhisperer.analyzer.preprocessing as preprocessing#Imports from Capturefrom chipwhisperer.analyzer.attacks.CPA import CPAfrom chipwhisperer.analyzer.attacks.CPAProgressive import CPAProgressiveimport chipwhisperer.analyzer.attacks.models.AES128_8bit#Imports from utilList class userScript(AutoScriptBase): preProcessingList = [] def initProject(self): pass  def initPreprocessing(self): self.preProcessingList = [] return self.preProcessingList  def initAnalysis(self): self.attack = CPA(self.parent, console=self.console, showScriptParameter=self.showScriptParameter) self.attack.setAnalysisAlgorithm(CPAProgressive,chipwhisperer.analyzer.attacks.models.AES128_8bit,chipwhisperer.analyzer.attacks.models.AES128_8bit.LEAK_HW_INVSBOXOUT_FIRSTROUND) self.attack.setTraceStart(0) self.attack.setTracesPerAttack(99) self.attack.setIterations(1) self.attack.setReportingInterval(10) self.attack.setTargetBytes([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]) self.attack.setTraceManager(self.traceManager()) self.attack.setProject(self.project()) self.attack.setPointRange((0,10992)) return self.attack  def initReporting(self, results): results.setAttack(self.attack) results.setTraceManager(self.traceManager()) self.results = results  def doAnalysis(self): self.attack.doAttack()</pre> = Appendix C AES-256 13th Round Key Script = '''NB: This script works for 0.10 release or later, see local copy in doc/html directory of chipwhisperer release if you need earlier versions''' Full attack script, copy/paste into a file then add as active attack script: <pre># AES-256 13th Round Key Scriptfrom chipwhisperer.common.autoscript import AutoScriptBase#Imports from Preprocessingimport chipwhisperer.analyzer.preprocessing as preprocessing#Imports from Capturefrom chipwhisperer.analyzer.attacks.CPA import CPAfrom chipwhisperer.analyzer.attacks.CPAProgressive import CPAProgressiveimport chipwhisperer.analyzer.attacks.models.AES128_8bit# Imports from utilList # Imports for AES256 Attackfrom chipwhisperer.analyzer.attacks.models.AES128_8bit import getHWfrom chipwhisperer.analyzer.models.aes.funcs import sbox, inv_sbox, inv_shiftrows, inv_mixcolumns, inv_subbytes class AES256Attack(object): numSubKeys = 16  @staticmethod def leakage(textin, textout, guess, bnum, setting, state): if setting == 13: knownkey = [0xea, 0x79, 0x79, 0x20, 0xc8, 0x71, 0x44, 0x7d, 0x46, 0x62, 0x5f, 0x51, 0x85, 0xc1, 0x3b, 0xcb] xored = [knownkey[i] ^ textin[i] for i in range(0, 16)] block = xored block = inv_shiftrows(block) block = inv_subbytes(block) block = inv_mixcolumns(block) block = inv_shiftrows(block) result = block return getHW(inv_sbox((result[bnum] ^ guess))) class userScript(AutoScriptBase): preProcessingList = [] def initProject(self): pass  def initPreprocessing(self): self.preProcessingResyncSAD0 = preprocessing.ResyncSAD.ResyncSAD(self.parent) self.preProcessingResyncSAD0.setEnabled(True) self.preProcessingResyncSAD0.setReference(rtraceno=0, refpoints=(9063,9177), inputwindow=(9010,9180)) self.preProcessingList = [self.preProcessingResyncSAD0,] return self.preProcessingList  def initAnalysis(self): self.attack = CPA(self.parent, console=self.console, showScriptParameter=self.showScriptParameter) self.attack.setAnalysisAlgorithm(CPAProgressive, AES256Attack, 13) self.attack.setTraceStart(0) self.attack.setTracesPerAttack(100) self.attack.setIterations(1) self.attack.setReportingInterval(25) self.attack.setTargetBytes([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]) self.attack.setTraceManager(self.traceManager()) self.attack.setProject(self.project()) self.attack.setPointRange((8000,10990)) return self.attack  def initReporting(self, results): results.setAttack(self.attack) results.setTraceManager(self.traceManager()) self.results = results  def doAnalysis(self): self.attack.doAttack()</pre> = Appendix D AES-256 IV Attack Script = '''NB: This script works for 0.10 release or later, see local copy in doc/html directory of chipwhisperer release if you need earlier versions''' Full attack script, copy/paste into a file then add as active attack script: <pre>#IV Attack Scriptfrom chipwhisperer.common.autoscript import AutoScriptBase#Imports from Preprocessingimport chipwhisperer.analyzer.preprocessing as preprocessing#Imports from Capturefrom chipwhisperer.analyzer.attacks.CPA import CPAfrom chipwhisperer.analyzer.attacks.CPAProgressive import CPAProgressiveimport chipwhisperer.analyzer.attacks.models.AES128_8bit# Imports from utilList # Imports for AES256 Attackfrom chipwhisperer.analyzer.attacks.models.AES128_8bit import getHW #Imports for IV Attackfrom Crypto.Cipher import AES class AESIVAttack(object): numSubKeys = 16  @staticmethod def leakage(textin, textout, guess, bnum, setting, state): knownkey = [0x94, 0x28, 0x5D, 0x4D, 0x6D, 0xCF, 0xEC, 0x08, 0xD8, 0xAC, 0xDD, 0xF6, 0xBE, 0x25, 0xA4, 0x99, 0xC4, 0xD9, 0xD0, 0x1E, 0xC3, 0x40, 0x7E, 0xD7, 0xD5, 0x28, 0xD4, 0x09, 0xE9, 0xF0, 0x88, 0xA1] knownkey = str(bytearray(knownkey)) ct = str(bytearray(textin))  aes = AES.new(knownkey, AES.MODE_ECB) pt = aes.decrypt(ct) return getHW(bytearray(pt)[bnum] ^ guess) class userScript(AutoScriptBase): preProcessingList = [] def initProject(self): pass  def initPreprocessing(self): self.preProcessingResyncSAD0 = preprocessing.ResyncSAD.ResyncSAD(self.parent) self.preProcessingResyncSAD0.setEnabled(True) self.preProcessingResyncSAD0.setReference(rtraceno=0, refpoints=(6300,6800), inputwindow=(6000,7200)) self.preProcessingResyncSAD1 = preprocessing.ResyncSAD.ResyncSAD(self.parent) self.preProcessingResyncSAD1.setEnabled(True) self.preProcessingResyncSAD1.setReference(rtraceno=0, refpoints=(4800,5100), inputwindow=(4700,5200)) self.preProcessingList = [self.preProcessingResyncSAD0,self.preProcessingResyncSAD1,] return self.preProcessingList  def initAnalysis(self): self.attack = CPA(self.parent, console=self.console, showScriptParameter=self.showScriptParameter) self.attack.setAnalysisAlgorithm(CPAProgressive, AESIVAttack, None) self.attack.setTraceStart(0) self.attack.setTracesPerAttack(100) self.attack.setIterations(1) self.attack.setReportingInterval(25) self.attack.setTargetBytes([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]) self.attack.setTraceManager(self.traceManager()) self.attack.setProject(self.project()) self.attack.setPointRange((4800,6500)) return self.attack  def initReporting(self, results): results.setAttack(self.attack) results.setTraceManager(self.traceManager()) self.results = results  def doAnalysis(self): self.attackNano.doAttack()</pre> {{Template:Tutorials}}
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