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fixed phew

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This commit is contained in:
lightningitoid
2025-10-26 22:25:05 +07:00
parent 6b96a097c3
commit e0d2de93f2
3 changed files with 117 additions and 62 deletions
Download Patch File Download Diff File Expand all files Collapse all files
receiver/challenges/Phew.py
+39 -34
View File
@@ -9,7 +9,7 @@ class Phew(Challenge):
flag_location = 'flags/phew.txt'
history_location = 'history/phew.txt'
_CONTAINER = "phew_container"
_CONTAINER = "phew_container"
_SERVICE_CMD = ["docker", "exec", "-i", _CONTAINER, "python3", "/home/ctfuser/chall/src/chall.py"]
_HEX_RE = re.compile(r'^[0-9a-fA-F]+$')
@@ -76,6 +76,7 @@ class Phew(Challenge):
def check(self):
try:
# parity check
with open(self.flag_location, 'r') as f:
host_flag = f.read().strip()
container_flag = self._read_container_flag()
@@ -93,12 +94,12 @@ class Phew(Challenge):
out = self._read_until(proc, "\n", timeout=3.0)
ct_hex = self._expect_hex_field(out, "ct")
self._read_until(proc, "> ", timeout=3.0)
self._send_line(proc, "4")
self._send_line(proc, "0")
try:
proc.wait(timeout=2.0)
except subprocess.TimeoutExpired:
proc.kill()
raise AssertionError("Program did not exit after option 4 (encrypt)")
raise AssertionError("Program did not exit after exit command (encrypt)")
return ct_hex
finally:
if proc.poll() is None:
@@ -115,38 +116,59 @@ class Phew(Challenge):
out = self._read_until(proc, "\n", timeout=3.0)
pt_hex = self._expect_hex_field(out, "pt")
self._read_until(proc, "> ", timeout=3.0)
self._send_line(proc, "4")
self._send_line(proc, "0")
try:
proc.wait(timeout=2.0)
except subprocess.TimeoutExpired:
proc.kill()
raise AssertionError("Program did not exit after option 4 (decrypt)")
raise AssertionError("Program did not exit after exit command (decrypt)")
return pt_hex
finally:
if proc.poll() is None:
proc.kill()
def run_bingo_once() -> str:
def run_keyct_once() -> str:
proc = self._spawn()
try:
self._read_until(proc, "> ", timeout=10.0)
self._send_line(proc, "2")
self._send_line(proc, "4")
out = self._read_until(proc, "\n", timeout=3.0)
ct_hex = self._expect_hex_field(out, "ct")
# exit fast
self._read_until(proc, "> ", timeout=3.0)
self._send_line(proc, "4")
self._send_line(proc, "0")
try:
proc.wait(timeout=2.0)
except subprocess.TimeoutExpired:
proc.kill()
raise AssertionError("Program did not exit after option 4 (bingo)")
raise AssertionError("Program did not exit after exit command (keyct)")
return ct_hex
finally:
if proc.poll() is None:
proc.kill()
ct1 = run_encrypt_once("414243444546")
def run_bingo_reject_wrong_key():
wrong_key_hex = "00" * 66
proc = self._spawn()
try:
self._read_until(proc, "> ", timeout=10.0)
self._send_line(proc, "2")
self._read_until(proc, "key (hex)", timeout=3.0)
self._read_until(proc, "> ", timeout=3.0)
self._send_line(proc, wrong_key_hex)
line = self._read_until(proc, "\n", timeout=3.0).strip()
assert "nope" in line.lower(), f"bingo did not reject wrong key; got: {line!r}"
self._read_until(proc, "> ", timeout=3.0)
self._send_line(proc, "0")
try:
proc.wait(timeout=2.0)
except subprocess.TimeoutExpired:
proc.kill()
raise AssertionError("Program did not exit after exit command (bingo)")
finally:
if proc.poll() is None:
proc.kill()
ct1 = run_encrypt_once("414243444546")
assert ct1 and self._HEX_RE.match(ct1), "encrypt(1) did not return hex"
self.logger.info("[ok] encrypt produced hex")
@@ -161,31 +183,14 @@ class Phew(Challenge):
assert ct_a.lower() != ct_b.lower(), "Encryption appears deterministic for same plaintext"
self.logger.info("[ok] encrypt randomness")
b1 = run_bingo_once()
b2 = run_bingo_once()
assert b1.lower() != b2.lower(), "Bingo ciphertexts reused randomness"
self.logger.info("[ok] bingo randomness")
k1 = run_keyct_once()
k2 = run_keyct_once()
assert k1.lower() != k2.lower(), "key? ciphertexts reused randomness"
self.logger.info("[ok] key? randomness")
# Skip alarm test during SLA checks (takes 10+ seconds and may be patched)
# import time as _time
# start = _time.time()
# proc_alarm = self._spawn()
# try:
# try:
# proc_alarm.wait(timeout=20.0)
# except subprocess.TimeoutExpired:
# proc_alarm.kill()
# raise AssertionError("Alarm did not fire within 20s (possible patch/removal)")
# elapsed = _time.time() - start
# self.logger.info(f"[info] observed lifetime for alarm: {elapsed:.2f}s")
# if not (8.0 <= elapsed <= 12.0):
# raise AssertionError(f"Alarm window changed (expected ~10s): observed {elapsed:.2f}s")
# self.logger.info("[ok] signal.alarm(10) integrity")
# finally:
# if proc_alarm.poll() is None:
# proc_alarm.kill()
run_bingo_reject_wrong_key()
self.logger.info("[ok] bingo rejects wrong key")
# self.logger.info('Check passed for phew (custom cipher + alarm intact)')
return True
except Exception as e:
services/phew/dist/chall.py
Vendored
+39 -14
View File
@@ -1,31 +1,56 @@
#!/usr/bin/env python3
import signal
import os
from Pailier import *
from Crypto.Util.number import *
signal.alarm(50)
with open("/flag.txt", "rb") as f:
flag = f.read()
flag = bytes_to_long(flag)
flag_bytes = f.read()
key = os.urandom(66)
key_int = bytes_to_long(key)
cipher = pailier()
while True:
print("1. encrypt")
print("2. bingo")
print("3. decrypt")
print("4. exit")
print("4. key?")
inp = int(input("> "))
if inp==1:
if inp == 1:
print("pt (hex)")
inp = input("> ")
ct = cipher.encrypt(int(inp,16))
print('ct : ','{0:x}'.format(ct))
elif inp==2:
ct = cipher.encrypt(flag)
print('ct : ','{0:x}'.format(ct))
elif inp==3:
ct = cipher.encrypt(int(inp, 16))
print('ct : ', '{0:x}'.format(ct))
elif inp == 2:
print("key (hex)")
user_hex = input("> ").strip()
try:
user_key = bytes.fromhex(user_hex)
except Exception:
print("nope")
continue
if len(user_key) == 66 and user_key == key:
try:
print(flag_bytes.decode())
except Exception:
print(flag_bytes.hex())
else:
print("nope")
elif inp == 3:
print("ct (hex)")
inp = input("> ")
pt = cipher.decrypt(int(inp,16))
print('pt : ','{0:x}'.format(pt))
pt = cipher.decrypt(int(inp, 16))
print('pt : ', '{0:x}'.format(pt))
elif inp == 4:
ct = cipher.encrypt(key_int)
print('ct : ', '{0:x}'.format(ct))
else:
exit()
services/phew/src/chall.py
+39 -14
View File
@@ -1,31 +1,56 @@
#!/usr/bin/env python3
import signal
import os
from Pailier import *
from Crypto.Util.number import *
signal.alarm(50)
with open("/flag.txt", "rb") as f:
flag = f.read()
flag = bytes_to_long(flag)
flag_bytes = f.read()
key = os.urandom(66)
key_int = bytes_to_long(key)
cipher = pailier()
while True:
print("1. encrypt")
print("2. bingo")
print("3. decrypt")
print("4. exit")
print("4. key?")
inp = int(input("> "))
if inp==1:
if inp == 1:
print("pt (hex)")
inp = input("> ")
ct = cipher.encrypt(int(inp,16))
print('ct : ','{0:x}'.format(ct))
elif inp==2:
ct = cipher.encrypt(flag)
print('ct : ','{0:x}'.format(ct))
elif inp==3:
ct = cipher.encrypt(int(inp, 16))
print('ct : ', '{0:x}'.format(ct))
elif inp == 2:
print("key (hex)")
user_hex = input("> ").strip()
try:
user_key = bytes.fromhex(user_hex)
except Exception:
print("nope")
continue
if len(user_key) == 66 and user_key == key:
try:
print(flag_bytes.decode())
except Exception:
print(flag_bytes.hex())
else:
print("nope")
elif inp == 3:
print("ct (hex)")
inp = input("> ")
pt = cipher.decrypt(int(inp,16))
print('pt : ','{0:x}'.format(pt))
pt = cipher.decrypt(int(inp, 16))
print('pt : ', '{0:x}'.format(pt))
elif inp == 4:
ct = cipher.encrypt(key_int)
print('ct : ', '{0:x}'.format(ct))
else:
exit()