This Roxs

import string
from base64 import b64decode

# placeholder for the flag
flag = "NOONCTF{flag_placeholder}"


# Given encrypted flag
given = ['', '00111111', '01010010', '01101001', '00000100', '00111000', '01010101', '01111101', '00010010', '00010011', '00011111', '01101101', '01010101', '00001000', '00101000', '01110001', '01101011', '01101011', '01011000', '00011100', '00010011', '00110010', '01101110', '00001001', '01111100', '00110111', '00110100', '00101000', '00000100', '00110110', '00011010', '00101000', '00000100', '00001000', '00101000', '01110001', '01101011', '01101011', '01011000', '00011100', '00010011', '00110010', '01101111', '01010010', '00100110', '00001010', '01110011', '00000111', '01101011', '00100010', '00111000', '00111011', '00100001', '01101010', '00000010', '00000000', '01010101', '00110010', '00011110', '00110011', '00100010', '01101011', '01011000', '00011100', '00010011', '00110010', '01101110', '00001001', '01111111', '00110100', '00111100', '00110101', '00010001', '00100100', '01111111', '01010010', '00100110', '00000101', '01111000', '00001101']


# Get the first letter of the flag
def get_first_letter():
    first_letter_guess = list(
        string.ascii_lowercase + string.ascii_uppercase + string.digits + '{}'
    )
    return first_letter_guess


# Encrypt the flag
def encrypt(flag):
    arr = []

    for i in range(len(flag) - 1):

        c = format(ord(flag[i]), 'b')
        cn = format(ord(flag[i + 1]), 'b')

        if len(c) < 8:
            c = ((8 - len(c)) * "0") + c
        if len(cn) < 8:
            cn = ((8 - len(cn)) * "0") + cn

        item = []
        for l in range(len(c)):
            item.append(str(int(c[l]) ^ int(cn[l])))

        arr.append("".join([str(e) for e in item]))
    return arr



# Decrypt the flag after adding the first letter to the encrypted flag
def decrypt(given_copy, first_letter):
    # Convert the first letter to binary
    first_letter_byte = format(ord(first_letter), 'b')

    # Add padding to the first letter if it is less than 8 bits
    if len(first_letter_byte) < 8:
        first_letter_byte = ((8 - len(first_letter_byte)) * "0") + first_letter_byte


    # Copy the given flag to avoid changing the original flag
    tmp = given_copy.copy()

    # Add the first letter to the beginning of the flag
    tmp[0] = first_letter_byte

    for i in range(len(tmp) - 1):
        item = []
        for l in range(len(tmp[i])):
            item.append(str(int(tmp[i][l]) ^ int(tmp[i + 1][l])))

        tmp[i] = "".join([str(e) for e in item])

    return "".join([chr(int(tmp[i], 2)) for i in range(len(tmp))])


# Print the flag to a file named "CTF_Match.txt" to match the CTF pattern
def print_flag(flag):
    with open("CTF_Match.txt", "a") as file:
        file.write(flag + "\n")


def main():
    # Get the first letter of the flag
    first_letter_guess = get_first_letter()

    # Decrypt the flag after adding the first letter to the encrypted flag
    for c in first_letter_guess:
        try:
            decrypted = decrypt(given, c)
            decrypted = b64decode(decrypted).decode("utf-8")
            print_flag(decrypted)
        except:
            pass


if __name__ == "__main__":
    main()