def check_control_bits(packet, counter):
amount = 0
temp_counter = Bits(int=counter, length=4)
pos = temp_counter.find('0b1')
pos_int = pos[0]
for i in range(1, 8):
temp_pos = Bits(int=i, length=4)
res = BitArray(temp_pos ^ temp_counter)
if res._readbin(1, pos_int) == '0' and packet._readbin(
1, i - 1) == '1':
amount += 1
return amount
def TH260_GetFeatures(self, device: int = 0):
"""
Use the predefined bit feature values in th260defin.h (FEATURE_xxx) to extract individual bits through a bitwise AND.
Typically this is only for information, or to check if your board has a specific (optional) capability.
#define FEATURE_DLL 0x0001 // DLL License available
#define FEATURE_TTTR 0x0002 // TTTR mode available
#define FEATURE_MARKERS 0x0004 // Markers available
#define FEATURE_LOWRES 0x0008 // Long range mode available
#define FEATURE_TRIGOUT 0x0010 // Trigger output available
#define FEATURE_PROG_TD 0x0020 // Programmable deadtime available
Parameters
----------
device: (int) device index if multiple devices 0..3 (default 0)
Returns
-------
list of str listing the hardware features
"""
feature = c_int()
res = self._TH260_GetFeatures(device, byref(feature))
ret=[]
if res == 0:
feature = Bits(int=feature.value, length=32)
if len(feature.find('0x0001')) != 0:
ret.append("FEATURE_DLL")
if len(feature.find('0x0002')) != 0:
ret.append("FEATURE_TTTR")
if len(feature.find('0x0004')) != 0:
ret.append("FEATURE_MARKERS")
if len(feature.find('0x0008')) != 0:
ret.append("FEATURE_LOWRES")
if len(feature.find('0x0010')) != 0:
ret.append("FEATURE_TRIGOUT")
if len(feature.find('0x0020')) != 0:
ret.append("FEATURE_PROG_TD")
return ret
else:
raise IOError(ErrorCodes(res).name)
def testFind(self):
a = Bits('0xabcd')
r = a.find('0xbc')
self.assertEqual(r[0], 4)
r = a.find('0x23462346246', bytealigned=True)
self.assertFalse(r)
#!/usr/bin/env python3
from PIL import Image
from bitstring import Bits
import requests
# Download target image
targetUrl = 'https://jupiter.challenges.picoctf.org/static/011955b303f293d60c8116e6a4c5c84f/buildings.png'
targetFilename = 'buildings.png'
with open(targetFilename, 'xb') as f:
r = requests.get(targetUrl)
f.write(r.content)
# Extract lsb bits
with Image.open(targetFilename, 'r') as img:
imgData = img.getdata()
rgbBytes = [byte for pixel in imgData for byte in pixel[:3]]
lsbBits = [byte & 1 for byte in rgbBytes]
# Decode message from bits, also remove null bytes for aesthetics
message = Bits(lsbBits)
nullPos = message.find('0b00000000', bytealigned=True)[0]
decodedMessage = message[:nullPos].tobytes().decode()
print(f"Flag: {decodedMessage}")
def testFind(self):
a = Bits('0xabcd')
r = a.find('0xbc')
self.assertEqual(r[0], 4)
r = a.find('0x23462346246', bytealigned=True)
self.assertFalse(r)
