def caesar():
key = 1
is_error = False
for index, arg in enumerate(sys.argv):
if arg in ['--key', '-k'] and len(sys.argv) > index + 1:
key = int(sys.argv[index + 1])
del sys.argv[index]
del sys.argv[index]
break
for index, arg in enumerate(sys.argv):
if arg in ['--encrypt', '-e']:
del sys.argv[index]
break
if arg in ['--decrypt', '-d']:
key = -key
del sys.argv[index]
break
if len(sys.argv) == 1:
is_error = True
else:
for arg in sys.argv:
if arg.startswith('-'):
is_error = True
if is_error:
print(
f'Usage: python {sys.argv[0]} [ --key <key> ] [ --encrypt|decrypt ] <text>'
)
else:
print(encrypt(' '.join(sys.argv[1:]), key))
def crack_caesar(input_file, output_file):
"""This function reads encrypted text from an input file and iterates over the 25 possible
caesar ciphers to determine the most likely decrypted plaintext message and caesar cipher
key used to encrypt the text. For each caesar cipher, the number of valid english words are
determined by checking against a dictionary provided by the `pyenchant` module. The most
likely plaintext and key are determined by the caesar cipher containing the highest number of
valid english words.
"""
ciphertext = input_file.read()
en_dict = enchant.Dict('en_US')
max_num_valid_words = 0
# tqdm module enables us to wrap ANY iterable with `tdqm(iterable` to turn our loops
# into a smart progress bar!
for key in tqdm(range(1, 26)):
plaintext = encrypt(ciphertext, -key)
num_valid_words = 0
for word in plaintext.split(' '):
if en_dict.check(word):
num_valid_words += 1
if num_valid_words > max_num_valid_words:
max_num_valid_words = num_valid_words
best_plaintext = plaintext
best_key = key
click.echo(f'The most likely encryption key is {best_key}')
output_file.write(best_plaintext)
def caesar(text, decrypt, key):
text_string = ' '.join(text)
if decrypt:
key = -key
cyphertext = encrypt(text_string, key)
# echo is same as print
click.echo(cyphertext)
def caesar(input_file, output_file, decrypt, key):
if input_file:
text = input_file.read()
else:
text = click.prompt('Enter a text', hide_input=not decrypt)
if decrypt:
key = -key
cyphertext = encrypt(text, key)
if output_file:
output_file.write(cyphertext)
else:
click.echo(cyphertext)
def caesar():
parser = argparse.ArgumentParser()
group = parser.add_mutually_exclusive_group()
group.add_argument('-e', '--encrypt', action='store_true')
group.add_argument('-d', '--decrypt', action='store_true')
parser.add_argument('text', nargs='*')
parser.add_argument('-k', '--key', type=int, default=1)
args = parser.parse_args()
text_string = ' '.join(args.text)
key = args.key
if args.decrypt:
key = -key
cyphertext = encrypt(text_string, key)
print(cyphertext)
def caesar_breaker(input_file, output_file):
cyphertext = input_file.read()
english_dictionnary = enchant.Dict("en_US")
best_number_of_english_words = 0
for key in tqdm(range(26)):
plaintext = encrypt(cyphertext, -key)
number_of_english_words = 0
for word in plaintext.split(' '):
if word and english_dictionnary.check(word):
number_of_english_words += 1
if number_of_english_words > best_number_of_english_words:
best_number_of_english_words = number_of_english_words
best_plaintext = plaintext
best_key = key
click.echo(f'The most likely encryption key is {best_key}. It gives the following plaintext:\n\n{best_plaintext[:1000]}...')
output_file.write(best_plaintext)
def caesar(input_file, output_file, key, decrypt):
"""This function uses the click module to parse the
arguments passed in from the command line and encrypts/decrypts
the message using the `encrypt` function from the `caesar_encryption`
module. Error and handling and usage (e.g. --help) is automatically
generated for us.
"""
if input_file:
text = input_file.read()
else:
# if user wants to encrypt text, we don't want to have this show up in the command history
text = click.prompt('Please enter a text', hide_input=not decrypt)
if decrypt:
key = -key
ciphertext = encrypt(text, key)
if output_file:
output_file.write(ciphertext)
else:
click.echo(ciphertext)
def main(plain_text, shift, key=None):
encrypted_msg = caesar_encryption.encrypt(text, shift)
decrypted_msg = caesar_decryption.decrypt(encrypted_msg, key)
return encrypted_msg, decrypted_msg