Hack for the Defcon 28 WeBadge

main.py

# WeBadge for DefCon#27
# From your friends in We Work InfoSec
# Makes buddies with up to 4 Shitty Add-Ons
import board
import time
import busio
from digitalio import DigitalInOut, Direction, Pull
from analogio import AnalogIn
from pulseio import PWMOut

# The "W" and "E" Leds. Use PulseIO to PWM the brightness
e = PWMOut(board.LEDE, frequency=5000, duty_cycle=0)
w = PWMOut(board.LEDW, frequency=5000, duty_cycle=0)

# Init the photosensor, get a reading to set LED brightness
photocell = AnalogIn(board.PHOTO)
def getMaxBright():
    #return min(photocell.value + 3000, 65535)
    return min(photocell.value, 65535)

# Setup the Shitty Add-Ons so they have power (we can PWM only POW1)
power1 = PWMOut(board.POW1, frequency=5000, duty_cycle=0)
power2 = DigitalInOut(board.POW2)
power2.direction = Direction.OUTPUT
power3 = DigitalInOut(board.POW3)
power3.direction = Direction.OUTPUT
power4 = DigitalInOut(board.POW4)
power4.direction = Direction.OUTPUT

t = 0
x0 = 0
x1 = 0
x2 = 0
y1 = 0
t = 0
THRESHOLD = 10000
INTERVAL = 0.02
BRIGHTNESS = 60000

def on_detection():
  global w, e
  for i in range(4):
    w.duty_cycle = 0
    e.duty_cycle = BRIGHTNESS
    time.sleep(0.25)
    w.duty_cycle = BRIGHTNESS
    e.duty_cycle = 0
    time.sleep(0.25)
    
def main():
  while True:
    # input
    x = int(photocell.value)
    x2 = x1
    x1 = x0
    x0 = x
    # apply a high-pass filter
    y = (x2 + x0 - x1 - x1)
    if y < 0:
      y = -y  # diode
    y = max(0, min(65535, y))
    # apply exponential smoothing so we don't flash right away
    y1 = y1 * 0.9 + y * 0.1
    if y1 > THRESHOLD:
      # Flash to indicate signal detection
      on_detection()
      # reset state
      y1 = y = 0
      x1 = x0 = x2 = x = 0

    t = 1 - t
    w.duty_cycle = e.duty_cycle = int(BRIGHTNESS * t)
    time.sleep(INTERVAL)

main()