INNER CODE UNIT · Python
print_linewrapped
rishitsaiya/CTFlearn-Writeups · Cryptography/ALEXCTF CR2: Many time secrets/cribdrag.py:34
def print_linewrapped(text):
line_width = 40
text_len = len(text)
for chunk in xrange(0,text_len,line_width):
if chunk > text_len-line_width:
print str(chunk) + chr(9) + text[chunk:]
else:
print str(chunk) + chr(9) + text[chunk:chunk+line_width]
parser = argparse.ArgumentParser(description='cribdrag, the interactive crib dragging script, allows you to interactively decrypt ciphertext using a cryptanalytic technique known as "crib dragging". This technique involves applying a known or guessed part of the plaintext (a "crib") to every possible position of the ciphertext. By analyzing the result of each operation and the likelihood of the result being a successful decryption based on the expected format and language of the plaintext one can recover the plaintext by making educated guesses and adaptive application of the crib dragging technique.')
parser.add_argument('ciphertext', help='Ciphertext, encoded in an ASCII hex format (ie. ABC would be 414243)')
parser.add_argument('-c', '--charset', help='A regex-style character set to be used to identify best candidates for successful decryption (ex: for alphanumeric characters and spaces, use "a-zA-Z0-9 ")', default='a-zA-Z0-9.,?! :;\'"')
args = parser.parse_args()
ctext = args.ciphertext.decode('hex')
ctext_len = len(ctext)