Hackvent_2018/Teaser/_ZOoxjUSe1OVB7OPoVrsX.pdf.extracted/decode_qr.py
Roman Hergenreder aa56104b3f Progress
2018-12-07 13:52:13 +01:00

148 lines
4.0 KiB
Python

#!/usr/bin/python
from PIL import Image
def invert(value):
return ''.join(["1" if x == "0" else "0" for x in value])
# Load Image
im = Image.open('QR3C_cropped.png')
pix = im.load()
tiles = 21
tileSize = im.size[0] // tiles
version = (tiles - 17) // 4
print("tiles=%d tileSize=%d version=%d" % (tiles, tileSize, version))
# Data Array
data = [[0 for x in range(tiles)] for y in range(tiles)]
# Fill data
# Black -> 111
# White -> 000
# Blue -> 110 ...
for y in range(tiles):
for x in range(tiles):
x_mid = x * tileSize + 0.5 * tileSize
y_mid = y * tileSize + 0.5 * tileSize
color = pix[x_mid, y_mid]
data[x][y] = invert("%d%d%d" % ( color[0] // 255, color[1] // 255, color[2] // 255 ))
def blackWhiteValue(string):
new_value = ""
if len(string) % 3 != 0:
print("Cannot return black white value of", string)
return new_value
for i in range(len(string) // 3):
new_value += string[i * 3]
return new_value
mask1 = [data[8][18], data[8][17], data[8][16]]
mask2 = [data[2][8], data[3][8], data[4][8]]
if mask1 != mask2:
print("masks do not match")
exit()
mask = [''.join(mask1[i][j] for i in range(3)) for j in range(3)]
print("Mask:", mask)
def apply_mask(x, y, bit, mask):
doInvert = False
if mask == "111":
doInvert = x % 3 == 0
elif mask == "110":
doInvert = (x + y) % 3 == 0
elif mask == "101":
doInvert = (x + y) % 2 == 0
elif mask == "100":
doInvert = y % 2 == 0
elif mask == "000":
doInvert = ((x*y) % 2) + ((x + y) % 3) == 0
return invert(bit) if doInvert else bit
def get_masked_value(x, y):
return ''.join([apply_mask(x, y, data[x][y][i], mask[i]) for i in range(3)])
def read_block(x, y, orientation):
indizes = []
if orientation == "UP":
indizes = [[0,0], [-1,0], [0,-1], [-1,-1], [0,-2], [-1,-2], [0, -3], [-1, -3]]
elif orientation == "LEFT_TOP":
indizes = [[0,0], [-1,0], [0,-1], [-1,-1], [-2,-1], [-3,-1], [-2, 0], [-3, 0]]
elif orientation == "DOWN":
indizes = [[0,0], [-1,0], [0,1], [-1,1], [0,2], [-1,2], [0, 3], [-1, 3]]
elif orientation == "LEFT_BOTTOM":
indizes = [[0,0], [-1,0], [0,1], [-1,1], [-2,1], [-3,1], [-2, 0], [-3, 0]]
return (''.join([get_masked_value(x + offset[0], y + offset[1]) for offset in indizes]))
def map_alphanumeric(x):
if x < 10:
return chr(ord('0') + x)
elif x < 36:
return chr(ord('A') + x - 10)
else:
special = { 36: " ", 37: "$", 38: "%", 39: "*", 40: "+", 41: "-", 42: ".", 43: "/", 44: ":" }
if x in special:
return special[x]
else:
print("unknown special character:", x)
return "?"
def decode_alphanumeric(x):
a = x // 45
b = x % 45
return map_alphanumeric(a) + map_alphanumeric(b)
encoding = blackWhiteValue(data[20][20] + data[19][20] + data[20][19] + data[19][19])
# encoding = data[20][20] + data[19][20] + data[20][19] + data[19][19]
# encoding = [get_masked_value(20, 20), get_masked_value(19, 20), get_masked_value(20, 19), get_masked_value(19, 19)]
print("Encoding:", encoding)
len_block = read_block(20, 18, "UP")
print("Length:", int(len_block, 2))
# 19 Blocks
blocks = ''.join([
read_block(20, 14, "UP"),
read_block(20, 10, "LEFT_TOP"),
read_block(18, 11, "DOWN"),
read_block(18, 15, "DOWN"),
read_block(18, 19, "LEFT_BOTTOM"),
read_block(16, 18, "UP"),
read_block(16, 14, "UP"),
read_block(16, 10, "LEFT_TOP"),
read_block(14, 11, "DOWN"),
read_block(14, 15, "DOWN")
])
channels = ["", "", ""]
blockSize = 3
for i in range(len(blocks) // blockSize):
channels[0] += blocks[i*3]
channels[1] += blocks[i*3+1]
channels[2] += blocks[i*3+2]
# chunk = int(blocks[blockSize*i:blockSize*i+blockSize],2)
# string += chr(chunk)
# string += decode_alphanumeric(chunk)
line = ""
for c in channels:
for i in range(len(c) // 8):
line += chr(int(c[i*8:i*8+8], 2))
print(line)
# print(len(blocks) /8)
# print(''.join(blocks))
# for x in range(tiles):
# print(''.join(data[x]))