-
Notifications
You must be signed in to change notification settings - Fork 0
/
Vigenere_Cipher.py
55 lines (39 loc) · 1.64 KB
/
Vigenere_Cipher.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
# The Vigenère cipher, where the offset for each letter is determined by another text, called the key.
def vigenere(message, key, direction=1):
key_index = 0
alphabet = 'abcdefghijklmnopqrstuvwxyz'
final_message = ''
for char in message.lower():
#Append any non-letter character to the message
if not char.isalpha():
final_message += char
else:
#Find the right key character to encode/decode
key_char = key[key_index % len(key)]
key_index += 1
#Define the offset and the encrypted/decrypted letter
offset = alphabet.index(key_char)
index = alphabet.find(char)
new_index = (index + offset * direction) % len(alphabet)
final_message += alphabet[new_index]
return final_message
def encrypt(message, key):
return vigenere(message, key)
def decrypt(message, key):
return vigenere(message, key, -1)
# Asking for encryption or decryption
def main():
choice = input("\nDo you want to encrypt or decrypt the text message? ")
if choice == 'encrypt':
text = input("\nEnter the message to encrypt: ")
key = input("What is the key: ")
print("\nThe encrypted message is : ", encrypt(text, key))
elif choice == 'decrypt':
text = input("\nEnter the text to decrypt: ")
key = input("What is the key: ")
print("\nThe decrypted message is : ", decrypt(text, key))
else:
print("\nEnter properly (encrypt or decrypt)")
main()
print("<<<<< Welcome to Vigenere Cipher / Decipher >>>>>")
main()