Generate CTF flag with 32 bit hex hash and L33t lang conversion with wrapping flag format

genflag.py

#!/usr/bin/python3
# -*- coding: utf-8 -*-

import argparse
import random
import math
import random

char_map = [
    ["A", "a", "4", "@"],
    ["B", "b", "8"],
    ["C", "c"],
    ["D", "d"],
    ["E", "e", "3"],
    ["F", "f"],
    ["G", "g", "6", "9"],
    ["H", "h"],
    ["I", "i", "1"],
    ["J", "j"],
    ["K", "k"],
    ["L", "l", "1"],
    ["M", "m"],
    ["N", "n"],
    ["O", "o", "0"],
    ["P", "p"],
    ["Q", "q"],
    ["R", "r"],
    ["S", "s", "5", "$"],
    ["T", "t", "7"],
    ["U", "u"],
    ["V", "v"],
    ["W", "w"],
    ["X", "x"],
    ["Y", "y"],
    ["Z", "z", "2"],
]


def change(c):
    if c.isalpha():
        c = c.upper()
        char_set = char_map[ord(c) - ord("A")]
        new_c = char_set[random.randint(0, len(char_set) - 1)]
        return new_c, (c == new_c) * math.log2(len(char_set))
    else:
        return c, 0


def main():
    global args
    parser = argparse.ArgumentParser()
    parser.add_argument("--fmt", help="flag fomat", default="flag")
    parser.add_argument("flag", help="origin flag")
    args = parser.parse_args()
    entropy = 0
    flag = ""
    for c in args.flag:
        new_c, e = change(c)
        flag += new_c
        entropy = e

    md5hash = "%032x" % random.getrandbits(128)

    flag = "_".join(flag.split())
    flag = "%s{%s}" % (args.fmt, f"{md5hash}_{flag}")
    print(flag)
    print(f"Added entropy: {entropy:.2f} bits")


if __name__ == "__main__":
    main()

"""
python3 genflag.py "The End of the Road"         
flag{0646e447c90a1ef09e572add4b4784b3_The_3Nd_Of_7he_r0@D}
Added entropy: 5.17 bits
python3 genflag.py --fmt winjactf "The End of the Road"
winjactf{25ffcf80db3b46d336a97f166f281d55_7hE_3nd_of_7HE_R0aD}
Added entropy: 6.17 bits
python3 genflag.py --fmt winja "The End of the Road"
winja{8499973e6659192b581e16f07bc1e9c7_Th3_3ND_Of_7hE_RO@d}
Added entropy: 9.34 bits
"""