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@andgein andgein/wired_csv.py Secret
Created Jun 29, 2018

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Google CTF 2018: Wired CSV solution
import csv
FILENAME = 'data.csv'
HSYNC = 1 / 15700
SCANCODES = ["L", "J", ";", "{F1}", "{F2}", "K", "+", "*", "O", "{NULL}", "P", "U", "{CR}", "I", "-", "=", "V", "Help", "C", "{F3}", "{F4}", "B", "X", "Z", "4", "{NULL}", "3", "6", "{Esc}", "5", "2", "1", ",", "{Spc}", ".", "N", "{NULL}", "M", "/", "{Inv}", "R", "{NULL}", "E", "Y", "{Tab}", "T", "W", "Q", "9", "{NULL}", "0", "7", "{BS}", "8", "<", ">", "F", "H", "D", "{NULL}", "Caps", "G", "S", "A"]
change_offsets = {0: [], 1: [], 2: [], 3: [], 4: [], 5: [], 6: [], 7: []}
def add_change_offset(line, time, value):
if time == '' or time == ' ':
return False
time = float(time)
change_offsets[line].append((time, int(value.strip())))
return True
def read():
with open(FILENAME) as csv_file:
reader = csv.reader(csv_file)
for idx, line in enumerate(reader):
if idx == 0:
continue
_, _, _, timek0, k0, timek1, k1, timek2, k2, timek3, k3, timek4, k4, timek5, k5, timekr1, kr1, timekr2, kr2 = line
if not add_change_offset(0, timek0, k0):
break
add_change_offset(1, timek1, k1)
add_change_offset(2, timek2, k2)
add_change_offset(3, timek3, k3)
add_change_offset(4, timek4, k4)
add_change_offset(5, timek5, k5)
add_change_offset(6, timekr1, kr1)
add_change_offset(7, timekr2, kr2)
def get_values(indices, time):
values = []
for i in range(len(change_offsets)):
index = indices[i]
while index < len(change_offsets[i]) and change_offsets[i][index][0] < time:
index += 1
indices[i] = index
values.append(change_offsets[i][index - 1][1])
return values
def parse_values(values):
for i in range(8):
# if i not in (3, 4):
values[i] = 1 - values[i]
kr1 = values[6]
kr2 = values[7]
scancode = 0
for x in values[:6][::-1]:
scancode = scancode * 2 + x
return kr1, kr2, scancode
def run():
time = 0
indices = [0] * len(change_offsets)
last_kr1 = 0
last_scancode = 0
answer = ''
while time < 20:
values = get_values(indices, time)
kr1, kr2, scancode = parse_values(values)
if last_kr1 == 0 and kr1 == 1:
if last_scancode != scancode:
print(f'Current time is {time}, values are {values}')
print(f'kr1 = {kr1}, kr2 = {kr2}, scancode = {scancode}, char = {SCANCODES[scancode]}')
answer += SCANCODES[scancode]
last_scancode = scancode
last_kr1 = kr1
time += HSYNC
print(answer)
if __name__ == '__main__':
read()
run()
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