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This tutorial is an add-on to [[Tutorial A5 Breaking AES-256 Bootloader]]. It continues working on the same firmware, showing how to obtain the hidden IV and signature in the bootloader. '''It is not possible to do this bonus tutorial without first completing the regular tutorial''', so please finish Tutorial A5 first.
''This tutorial is under construction! Check back in a few days.''
= Background =
== AES in CBC Mode ==
* Repeat of theory from tutorial
== The IV ==
* Suggest some ideas
== The Signature ==
* Timing attack
* Show firmware
= Attacking the IV =
Example:
<pre>#Imports for IV Attack
from 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>
= 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 Script
from chipwhisperer.common.autoscript import AutoScriptBase
#Imports from Preprocessing
import chipwhisperer.analyzer.preprocessing as preprocessing
#Imports from Capture
from chipwhisperer.analyzer.attacks.CPA import CPA
from chipwhisperer.analyzer.attacks.CPAProgressive import CPAProgressive
import chipwhisperer.analyzer.attacks.models.AES128_8bit
# Imports from utilList
# Imports for AES256 Attack
from chipwhisperer.analyzer.attacks.models.AES128_8bit import getHW
#Imports for IV Attack
from 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.attack.doAttack()</pre>
= Attacking the Signature =
''This tutorial is under construction! Check back in a few days.''
= Background =
== AES in CBC Mode ==
* Repeat of theory from tutorial
== The IV ==
* Suggest some ideas
== The Signature ==
* Timing attack
* Show firmware
= Attacking the IV =
Example:
<pre>#Imports for IV Attack
from 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>
= 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 Script
from chipwhisperer.common.autoscript import AutoScriptBase
#Imports from Preprocessing
import chipwhisperer.analyzer.preprocessing as preprocessing
#Imports from Capture
from chipwhisperer.analyzer.attacks.CPA import CPA
from chipwhisperer.analyzer.attacks.CPAProgressive import CPAProgressive
import chipwhisperer.analyzer.attacks.models.AES128_8bit
# Imports from utilList
# Imports for AES256 Attack
from chipwhisperer.analyzer.attacks.models.AES128_8bit import getHW
#Imports for IV Attack
from 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.attack.doAttack()</pre>
= Attacking the Signature =