CyberSpace CTF 2024 - Sole Writeup

csctf2024-sole-writeup.py

import string

var = {
    '27': ord('C'),
    '1': ord('S'),
    '2': ord('C'),
    '26': ord('T'),
    '3': ord('F'),
    '4': ord('{'),
    '23': ord('}'),
}

def var_to_solve(*args):
    unsolved_vars = []
    for arg in args:
        if not var.get(arg):
            unsolved_vars.append(arg)
    if len(unsolved_vars) == 1:
        return unsolved_vars[0]
    return None


def solve(var_name, callback):
    for c in string.printable:
        var[var_name] = ord(c)
        if callback():
            return True
    return False


while True:
    if v := var_to_solve('10', '17', '3'):
        solve(v, lambda: var['10'] + var['17'] + var['3'] == 0x5f76c)
    if v := var_to_solve('7', '25', '20'):
        solve(v, lambda: var['7'] * var['25'] * var['20'] == 0x8a9a8)
    if v := var_to_solve('27', '20', '13'):
        solve(v, lambda: var['27'] * var['20'] + var['13'] == 0x1308)
    if v := var_to_solve('7', '27', '10'):
        solve(v, lambda: var['7'] + var['27'] + var['10'] == 199)
    if v := var_to_solve('11', '20', '25'):
        solve(v, lambda: var['25'] - (var['11'] + var['20']) == -0xe89)
    if v := var_to_solve('3', '8', '1'):
        solve(v, lambda: var['3'] * var['8'] - var['1'] == 0x1f65)
    if v := var_to_solve('14', '8', '10'):
        solve(v, lambda: var['14'] * var['8'] * var['10'] == 0x429c0)
    if v := var_to_solve('26', '21', '13'):
        solve(v, lambda: var['26'] * var['21'] + var['13'] == 0x2640)
    if v := var_to_solve('8', '21', '3'):
        solve(v, lambda: var['8'] - var['21'] - var['3'] == -0x46)
    if v := var_to_solve('4', '19', '7'):
        solve(v, lambda: var['4'] - var['19'] - var['7'] == -0x3f)
    if v := var_to_solve('26', '22', '27'):
        solve(v, lambda: var['26'] * var['22'] + var['27'] == 0x14ef)
    if v := var_to_solve('1', '23', '15'):
        solve(v, lambda: var['1'] * var['23'] + var['15'] == 0x28f3)
    if v := var_to_solve('17', '6', '2'):
        solve(v, lambda: var['17'] * var['6'] * var['2'] == 0xda2ce)
    if v := var_to_solve('10', '3', '17'):
        solve(v, lambda: var['10'] - var['3'] + var['17'] == 0x5d)
    if v := var_to_solve('5', '6', '9'):
        solve(v, lambda: var['5'] + var['6'] - var['9'] == 0x88)
    if v := var_to_solve('23', '27', '9'):
        solve(v, lambda: var['23'] + var['27'] + var['9'] == 0x11f)
    if v := var_to_solve('4', '11', '20'):
        solve(v, lambda: var['4'] + var['11'] - var['20'] == 0x68)
    if v := var_to_solve('6', '3', '11'):
        solve(v, lambda: var['11'] + var['6'] * var['3'] == 0x2033)
    if v := var_to_solve('1', '20', '3'):
        solve(v, lambda: var['1'] - var['20'] + var['3'] == 0x51)
    if v := var_to_solve('10', '17', '7'):
        solve(v, lambda: var['7'] - (var['10'] * var['17']) == -0x157f)
    if v := var_to_solve('7', '9', '6'):
        solve(v, lambda: var['7'] - var['9'] - var['6'] == -0x81)
    if v := var_to_solve('20', '18', '19'):
        solve(v, lambda: var['20'] + var['18'] + var['19'] == 0xe0)
    if v := var_to_solve('21', '22', '11'):
        solve(v, lambda: var['21'] + var['22'] + var['11'] == 0xe8)
    if v := var_to_solve('13', '8', '3'):
        solve(v, lambda: var['13'] - var['8'] + var['3'] == 2)
    if v := var_to_solve('13', '8', '2'):
        solve(v, lambda: var['13'] * var['8'] + var['2'] == 0x1603)
    if v := var_to_solve('12', '22', '14'):
        solve(v, lambda: var['12'] + var['22'] + var['14'] == 0xd2)
    if v := var_to_solve('9', '1', '11'):
        solve(v, lambda: var['9'] + var['1'] - var['11'] == 0x7d)
    if v := var_to_solve('16', '1', '4'):
        solve(v, lambda: var['16'] - var['1'] - var['4'] == -0x6f)
    if v := var_to_solve('11', '12', '6'):
        solve(v, lambda: var['11'] - var['12'] - var['6'] == -0xa3)
    if v := var_to_solve('4', '1', '14'):
        solve(v, lambda: var['4'] + var['1'] - var['14'] == 0x9e)
    
    if len(var) == 26 and all([chr(v) in string.printable for v in var.values()]):
        break

result = [var['27'], var['1'], var['2'], var['26'], var['3'],
          var['4'], var['5'], var['6'], var['7'], var['8'], var['9'],
          var['10'], var['11'], var['12'], var['13'], var['14'], var['15'],
          var['16'], var['17'], var['18'], var['19'], var['20'], var['21'],
          var['22'], var['23']]
print(''.join(map(chr, result)))