Symmetric Decryption with

gistfile1.txt

# Encrypt / Decrypt
import base64
import sys
from cryptography.fernet import Fernet

action = input('Encrypt or Decrypt [e/d]?')

if action.lower() == 'encrypt' or action.lower() == 'e':
    secret = input('Secret Key: ')
    secret_bytes = int(secret).to_bytes(32, byteorder=sys.byteorder)
    key = base64.urlsafe_b64encode(secret_bytes)
    msg = input("Message: ")
    f = Fernet(key)
    cipher_text = f.encrypt(msg.encode())
    print("Using Secret: ", str(key))
    print("CipherText: ", str(cipher_text))

elif action.lower() == 'decrypt' or action.lower() == 'd':
    secret = input('Secret Key: ')
    secret_bytes = int(secret).to_bytes(32, byteorder=sys.byteorder)
    key = base64.urlsafe_b64encode(secret_bytes)
    f = Fernet(key)
    cipher_text = input("Cipher Text: ")
    print("Message: ", f.decrypt(cipher_text.encode()))
else:
    print("Enter 'e' or 'd' ")


# Brute Force
import base64
import sys
from cryptography.fernet import Fernet
from cryptography.fernet import InvalidToken

cipher_text = input("Cipher Text: ")
mod = int(input("Mod Limit: "))
print("...")
for i in range(1, mod):
    try:
        secret_bytes = int(i).to_bytes(32, byteorder=sys.byteorder)
        key = base64.urlsafe_b64encode(secret_bytes)
        f = Fernet(key)
        decoded_cipher = cipher_text.encode()
        decrypted = f.decrypt(decoded_cipher)
        print("Success")
        print("Secret {}: ".format(i), decrypted)
    except InvalidToken as e:
        print("Invalid {}".format(i))