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added lab2 questions

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This commit is contained in:
Student 2025-08-05 09:59:28 +05:30
parent 857ebf4a77
commit a1b2495e47
5 changed files with 99 additions and 11 deletions
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16
IS/Lab/Lab2/des.py
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@ -1,23 +1,18 @@
from Crypto.Cipher import DES
from Crypto.Util.Padding import pad, unpad
def des_cipher(key):
return DES.new(key.encode('utf-8'), DES.MODE_ECB)
def despad_ptext(text):
n = len(text) % 8
if n != 0:
return text + (' ' * (8 - n))
else:
return text
def des_en(ptext, key):
cipher = des_cipher(key)
ptext = despad_ptext(ptext).encode('utf-8')
return cipher.encrypt(ptext)
padded_text = pad(ptext.encode('utf-8'), DES.block_size)
return cipher.encrypt(padded_text)
def des_de(ctext, key):
cipher = des_cipher(key)
return cipher.decrypt(ctext).decode('utf-8').rstrip()
decrypted = unpad(cipher.decrypt(ctext), DES.block_size)
return decrypted.decode('utf-8')
def despad_key(key):
return key.ljust(8)[:8]
@ -25,7 +20,6 @@ def despad_key(key):
def main():
print("Welcome to DES (Original)")
ptext = input("Enter plaintext: ")
despad_ptext(ptext)
key = input("Enter key: ")
key = despad_key(key)
ctext = des_en(ptext, key)