65 lines
2.1 KiB
Python
65 lines
2.1 KiB
Python
|
import base64
|
||
|
|
ciphertext=input("Enter message to decode: ")
|
||
|
|
steponel = list(ciphertext)
|
||
|
|
stepone = ""
|
||
|
|
for i in range(len(steponel)-1):
|
||
|
|
stepone=stepone+steponel[i]
|
||
|
|
steptwo = stepone.encode('utf-8')
|
||
|
|
steptwob = base64.a85decode(steptwo)
|
||
|
|
steptwoc = steptwob.decode('utf-8')
|
||
|
|
def vigenere_dec(cipher,key):
|
||
|
|
alphabet = "abcdefghijklmnopqrstuvwxyz0123456789"
|
||
|
|
input_string = ""
|
||
|
|
dec_key = ""
|
||
|
|
dec_string = ""
|
||
|
|
dec_key = key
|
||
|
|
dec_key = dec_key.lower()
|
||
|
|
input_string = cipher
|
||
|
|
input_string = input_string.lower()
|
||
|
|
string_length = len(input_string)
|
||
|
|
expanded_key = dec_key
|
||
|
|
expanded_key_length = len(expanded_key)
|
||
|
|
while expanded_key_length < string_length:
|
||
|
|
expanded_key = expanded_key + dec_key
|
||
|
|
expanded_key_length = len(expanded_key)
|
||
|
|
key_position = 0
|
||
|
|
for letter in input_string:
|
||
|
|
if letter in alphabet:
|
||
|
|
position = alphabet.find(letter)
|
||
|
|
key_character = expanded_key[key_position]
|
||
|
|
key_character_position = alphabet.find(key_character)
|
||
|
|
key_position = key_position + 1
|
||
|
|
new_position = position - key_character_position
|
||
|
|
if new_position > 35:
|
||
|
|
new_position = new_position + 36
|
||
|
|
new_character = alphabet[new_position]
|
||
|
|
dec_string = dec_string + new_character
|
||
|
|
else:
|
||
|
|
dec_string = dec_string + letter
|
||
|
|
return(dec_string)
|
||
|
|
def stepfour(stepthree):
|
||
|
|
stepthree=str(int(stepthree,36))
|
||
|
|
test = list(stepthree)
|
||
|
|
if len(test)%3==1:
|
||
|
|
stepthree="00"+stepthree
|
||
|
|
if len(test)%3==2:
|
||
|
|
stepthree="0"+stepthree
|
||
|
|
stepthreel = list(stepthree)
|
||
|
|
stepfourl = [""]*int((float(len(stepthreel))/3))
|
||
|
|
k = 0
|
||
|
|
while k < len(stepthreel)-2:
|
||
|
|
stepfourl[int(k/3)] = stepthreel[k] + stepthreel[k+1] + stepthreel[k+2]
|
||
|
|
k = k + 3
|
||
|
|
for j in range(len(stepfourl)):
|
||
|
|
temp = stepfourl[j]
|
||
|
|
temp = int(temp)
|
||
|
|
temp = chr(temp)
|
||
|
|
stepfourl[j] = temp
|
||
|
|
stepfour=""
|
||
|
|
for l in range(len(stepfourl)):
|
||
|
|
stepfour = stepfour + stepfourl[l]
|
||
|
|
return(stepfour)
|
||
|
|
key = input("Enter encryption key: ")
|
||
|
|
stepthree = vigenere_dec(steptwoc, key)
|
||
|
|
stepfour = stepfour(stepthree)
|
||
|
|
print("Your decoded message: "+stepfour)
|