diff --git a/receiver/challenges/Phew.py b/receiver/challenges/Phew.py deleted file mode 100644 index 609e4da..0000000 --- a/receiver/challenges/Phew.py +++ /dev/null @@ -1,182 +0,0 @@ -from .Challenge import Challenge - -import subprocess -import time -import re -import os - -class Phew(Challenge): - flag_location = 'flags/phew.txt' - history_location = 'history/phew.txt' - - _CONTAINER = "phew_container" # <-- set to your container name - _SERVICE_CMD = ["docker", "exec", "-i", _CONTAINER, "python3", "/home/ctfuser/chall/src/chall.py"] - _HEX_RE = re.compile(r'^[0-9a-fA-F]+$') - - def _read_container_flag(self) -> str: - out = subprocess.run(["docker", "exec", self._CONTAINER, "cat", "/flag.txt"], - capture_output=True, text=True) - if out.returncode != 0 or not out.stdout.strip(): - raise FileNotFoundError("Flag not found in container (/flag.txt)") - return out.stdout.strip() - - def _spawn(self): - return subprocess.Popen( - self._SERVICE_CMD, - stdin=subprocess.PIPE, - stdout=subprocess.PIPE, - stderr=subprocess.STDOUT, - text=True, - bufsize=0, - ) - - def _read_until(self, proc, token, timeout=5.0, max_bytes=1_000_000): - start = time.time() - buf = [] - r = proc.stdout.read - while True: - if time.time() - start > timeout: - tail = ''.join(buf)[-500:] - raise TimeoutError(f"Timeout waiting for '{token}'. Got so far:\n{tail}") - ch = r(1) - if ch == "" and proc.poll() is not None: - raise RuntimeError(f"Process ended while waiting for '{token}'. Output:\n{''.join(buf)}") - buf.append(ch) - if len(buf) > max_bytes: - raise RuntimeError("Exceeded max read size") - if token in "".join(buf): - return "".join(buf) - - def _send_line(self, proc, s: str): - proc.stdin.write(s + "\n") - proc.stdin.flush() - - def _expect_hex_field(self, text: str, label: str) -> str: - """ - Extracts 'ct : ' or 'pt : ' (label = 'ct' or 'pt') - The service prints with spaces around the colon: 'ct : ' - """ - m = re.search(rf"{re.escape(label)}\s*:\s*([0-9a-fA-F]+)", text) - assert m, f"Missing '{label}' in output. Tail:\n{text[-400:]}" - hx = m.group(1) - assert self._HEX_RE.match(hx), f"{label} is not hex" - return hx - - def distribute(self, flag): - try: - os.makedirs(os.path.dirname(self.flag_location), exist_ok=True) - with open(self.flag_location, 'w') as f: - f.write(flag) - - os.makedirs(os.path.dirname(self.history_location), exist_ok=True) - with open(self.history_location, 'a') as f: - f.write(flag + '\n') - - self.logger.info(f'Flag {flag} written to {self.flag_location}') - return True - except Exception as e: - self.logger.error(f'Could not write flag to {self.flag_location}: {e}') - return False - - def check(self): - try: - with open(self.flag_location, 'r') as f: - host_flag = f.read().strip() - container_flag = self._read_container_flag() - assert host_flag == container_flag, 'Flag mismatch between host and container' - self.logger.info('[ok] flag parity (phew)') - - proc = self._spawn() - - def menu(): - self._read_until(proc, "> ", timeout=5.0) - - menu() - self._send_line(proc, "1") - self._read_until(proc, "pt (hex)", timeout=3.0) - self._read_until(proc, "> ", timeout=3.0) - pt_hex = "414243444546" # "ABCDEF" - self._send_line(proc, pt_hex) - out = self._read_until(proc, "\n", timeout=3.0) - ct_hex = self._expect_hex_field(out, "ct") - self.logger.info("[ok] encrypt(1) produced hex CT") - - menu() - self._send_line(proc, "3") - self._read_until(proc, "ct (hex)", timeout=3.0) - self._read_until(proc, "> ", timeout=3.0) - self._send_line(proc, ct_hex) - out_dec = self._read_until(proc, "\n", timeout=3.0) - pt_back_hex = self._expect_hex_field(out_dec, "pt") - # Normalize leading zeros for comparison - def norm(h): return (h.lstrip("0") or "0").lower() - assert norm(pt_back_hex) == norm(pt_hex), f"decrypt(encrypt(pt)) mismatch: {pt_back_hex} != {pt_hex}" - self.logger.info("[ok] decrypt(3) round-trip") - - menu() - self._send_line(proc, "1") - self._read_until(proc, "pt (hex)", timeout=3.0) - self._read_until(proc, "> ", timeout=3.0) - same_pt = "01" * 8 - self._send_line(proc, same_pt) - out_a = self._read_until(proc, "\n", timeout=3.0) - ct_a = self._expect_hex_field(out_a, "ct") - - menu() - self._send_line(proc, "1") - self._read_until(proc, "pt (hex)", timeout=3.0) - self._read_until(proc, "> ", timeout=3.0) - self._send_line(proc, same_pt) - out_b = self._read_until(proc, "\n", timeout=3.0) - ct_b = self._expect_hex_field(out_b, "ct") - - assert ct_a.lower() != ct_b.lower(), "Encryption appears deterministic for same plaintext" - self.logger.info("[ok] encrypt(1) randomness") - - menu() - self._send_line(proc, "2") - out2a = self._read_until(proc, "\n", timeout=3.0) - bingo1 = self._expect_hex_field(out2a, "ct") - - menu() - self._send_line(proc, "2") - out2b = self._read_until(proc, "\n", timeout=3.0) - bingo2 = self._expect_hex_field(out2b, "ct") - - assert bingo1.lower() != bingo2.lower(), "Bingo ciphertexts reused randomness" - self.logger.info("[ok] bingo(2) randomness") - - menu() - self._send_line(proc, "1") - self._read_until(proc, "pt (hex)", timeout=3.0) - self._read_until(proc, "> ", timeout=3.0) - pt_hex2 = "deadbeef" - self._send_line(proc, pt_hex2) - out_enc2 = self._read_until(proc, "\n", timeout=3.0) - ct2 = self._expect_hex_field(out_enc2, "ct") - - menu() - self._send_line(proc, "3") - self._read_until(proc, "ct (hex)", timeout=3.0) - self._read_until(proc, "> ", timeout=3.0) - self._send_line(proc, ct2) - out_dec2 = self._read_until(proc, "\n", timeout=3.0) - pt2_back = self._expect_hex_field(out_dec2, "pt") - assert norm(pt2_back) == norm(pt_hex2), f"decrypt(encrypt(pt2)) mismatch: {pt2_back} != {pt_hex2}" - self.logger.info("[ok] decrypt(3) round-trip (case 2)") - - menu() - self._send_line(proc, "4") - try: - proc.wait(timeout=2.0) - except subprocess.TimeoutExpired: - proc.kill() - raise AssertionError("Program did not exit after option 4") - self.logger.info("[ok] service exit on 4") - - self.logger.info('Check passed for phew') - return True - - except Exception as e: - self.logger.error(f'Could not check phew: {e}') - return False