Weak key

des.py

from Crypto.Cipher import DES
from bitarray import *

def int_to_nibble(i):
    bnr = bin(i).replace('0b','')
    x = bnr[::-1] 
    while len(x) < 4:
        x += '0'
    bnr = x[::-1]
    return bnr

def str_to_nibbles(s):
    arr = list(map(int_to_nibble, list(map(int, list(s)))))
    return arr

def nibble_to_bytes(n):
    return int(n).to_bytes(2, 'big')

# As described by https://academic.csuohio.edu/yuc/security/Chapter_06_Data_Encription_Standard.pdf  
key = bitarray(''.join(str_to_nibbles('0101010101010101'))).tobytes()
plaintext = bitarray(''.join(str_to_nibbles('1234567887654321'))).tobytes()

cipher = DES.new(key, DES.MODE_ECB)
msg = cipher.encrypt(plaintext)

print(plaintext)
print(msg)
print(cipher.encrypt(msg))

output.txt

○ → python des.py
b'\x124Vx\x87eC!'
b'\x81O\xe98X\x91T\xf7'
b'\x124Vx\x87eC!'