Merge branch 'main' of github.com:rayhanhanaputra/gemastik18-final

receiver/challenges/test_sheesh_standalone.py

@@ -0,0 +1,191 @@
+from .Challenge import Challenge
+
+import subprocess
+import time
+import re
+import os
+
+class Sheesh(Challenge):
+    flag_location    = 'flags/sheesh.txt'
+    history_location = 'history/sheesh.txt'
+
+    _CONTAINER   = "sheesh_container"
+    _SERVICE_CMD = ["docker", "exec", "-i", _CONTAINER, "python3", "/usr/local/bin/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:
+        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 (sheesh)')
+
+            proc = self._spawn()
+
+            def menu():
+                self._read_until(proc, "> ", timeout=5.0)
+
+            menu()
+
+            self._send_line(proc, "1")
+            self._read_until(proc, "pt: ", timeout=3.0)
+            pt_hex = "414243444546"  # "ABCDEF"
+            self._send_line(proc, pt_hex)
+            out = self._read_until(proc, "\n\n", timeout=3.0)
+            ct_hex = self._expect_hex_field(out, "ct")
+            ct = bytes.fromhex(ct_hex)
+            assert len(ct) == 16 + len(bytes.fromhex(pt_hex)), "CFB ct length mismatch (IV+PT)"
+            iv_a = ct[:16]
+            self.logger.info("[ok] encrypt(1) basic")
+
+            menu()
+            self._send_line(proc, "1")
+            self._read_until(proc, "pt: ", timeout=3.0)
+            pt_hex2 = "00" * 8
+            self._send_line(proc, pt_hex2)
+            out2 = self._read_until(proc, "\n\n", timeout=3.0)
+            ct2_hex = self._expect_hex_field(out2, "ct")
+            ct2 = bytes.fromhex(ct2_hex)
+            assert len(ct2) == 16 + len(bytes.fromhex(pt_hex2)), "Second CFB ct length mismatch"
+            iv_b = ct2[:16]
+            assert iv_a != iv_b, "CFB IV appears reused"
+            self.logger.info("[ok] encrypt(1) IV rotates")
+
+            menu()
+            self._send_line(proc, "3")
+            self._read_until(proc, "pt: ", timeout=3.0)
+            self._send_line(proc, "00" * 15)
+            out3a = self._read_until(proc, "\n", timeout=3.0)
+            assert "hmmm" in out3a.lower(), "Option 3 must reject non-16-byte input (15B)"
+
+            menu()
+            self._send_line(proc, "3")
+            self._read_until(proc, "pt: ", timeout=3.0)
+            self._send_line(proc, "00" * 17)
+            out3b = self._read_until(proc, "\n", timeout=3.0)
+            assert "hmmm" in out3b.lower(), "Option 3 must reject non-16-byte input (17B)"
+
+            menu()
+            self._send_line(proc, "3")
+            self._read_until(proc, "pt: ", timeout=3.0)
+            self._send_line(proc, "11" * 16)
+            out3 = self._read_until(proc, "\n\n", timeout=3.0)
+            ct3_hex = self._expect_hex_field(out3, "ct")
+            ct3 = bytes.fromhex(ct3_hex)
+            assert len(ct3) in (16, 32), f"Unexpected CT length for option 3: {len(ct3)} (expected 16 or 32)"
+            if len(ct3) == 16:
+                self.logger.info("[ok] get third(3): vuln flavor (16-byte CT)")
+            else:
+                self.logger.info("[ok] get third(3): patched flavor (32-byte CT)")
+
+            menu()
+            self._send_line(proc, "3")
+            out4 = self._read_until(proc, "\n", timeout=3.0)
+            assert "sheesh" in out4.lower(), "Second call to option 3 should be rejected with 'sheesh'"
+            self.logger.info("[ok] get third(3) lockout")
+
+            menu()
+            self._send_line(proc, "2")
+            out5 = self._read_until(proc, "\n\n", timeout=3.0)
+            iv1_hex = self._expect_hex_field(out5, "iv1")
+            iv2_hex = self._expect_hex_field(out5, "iv2")
+            ct5_hex = self._expect_hex_field(out5, "ct")
+            assert len(bytes.fromhex(iv1_hex)) == 16, "iv1 length invalid"
+            assert len(bytes.fromhex(iv2_hex)) == 16, "iv2 length invalid"
+            assert len(bytes.fromhex(ct5_hex)) >= 16 and len(bytes.fromhex(ct5_hex)) % 16 == 0, "CBC ct invalid length"
+            self.logger.info("[ok] profit(2) first call")
+
+            menu()
+            self._send_line(proc, "2")
+            out6 = self._read_until(proc, "\n\n", timeout=3.0)
+            iv1_hex_2 = self._expect_hex_field(out6, "iv1")
+            iv2_hex_2 = self._expect_hex_field(out6, "iv2")
+            assert iv1_hex_2 != iv1_hex or iv2_hex_2 != iv2_hex, "IVs did not change between consecutive '2' calls"
+            self.logger.info("[ok] profit(2) fresh IVs")
+
+            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")
+
+            proc_alarm = self._spawn()
+            self._read_until(proc_alarm, "zzz", timeout=190.0)  # 180s + slack
+            try:
+                proc_alarm.wait(timeout=5.0)
+            except subprocess.TimeoutExpired:
+                proc_alarm.kill()
+                raise AssertionError("Alarm fired but process did not exit")
+            self.logger.info("[ok] alarm fired ('zzz') and process self-terminated")
+
+            self.logger.info('Check passed for sheesh')
+            return True
+
+        except Exception as e:
+            self.logger.error(f'Could not check sheesh: {e}')
+            return False

receiver/flags/sheesh.txt

@@ -0,0 +1 @@
+GEMASTIK{PLACEHOLDER}

services/phew/Dockerfile

@@ -1,32 +0,0 @@
-FROM python:3.12-slim
-
-ARG PASSWORD=root
-ENV DEBIAN_FRONTEND=noninteractive
-ENV HOME=/home/ctf
-WORKDIR /home/ctf/chall
-
-RUN apt-get update && apt-get install -y --no-install-recommends \
-    openssh-server \
-    build-essential \
-    libffi-dev \
-    libssl-dev \
-    python3-dev \
-    bash \
-    && rm -rf /var/lib/apt/lists/*
-
-RUN useradd -m -d /home/ctf -s /bin/bash ctf && \
-    echo "ctf:${PASSWORD}" | chpasswd
-
-RUN mkdir -p /var/run/sshd
-
-COPY requirements.txt /tmp/requirements.txt
-RUN pip install --no-cache-dir -r /tmp/requirements.txt
-
-COPY ./src /home/ctf/chall/src
-COPY ./start.sh /start.sh
-RUN chmod +x /start.sh /home/ctf/chall/src/run.sh
-
-RUN chown -R root:root /home/ctf/chall && chmod -R 555 /home/ctf/chall
-
-EXPOSE 8000 22
-CMD ["/start.sh"]

services/phew/chall.py

@@ -1,126 +0,0 @@
-#!/usr/bin/env python3
-
-import os, sys, json, random, hashlib, hmac
-from Crypto.Cipher import AES
-from Crypto.Util.Padding import pad
-with open("/flag.txt", "rb") as f:
-    flag = f.read()
-
-menu = (
-    "1) encrypt\n"
-    "2) profit\n"
-    "3) nyerah\n"
-    ">> "
-)
-
-
-k = 1024  
-n = 169
-
-rng = random.SystemRandom()
-
-def rand(k_bits: int) -> int:
-    return rng.randrange(1, 1 << k_bits)
-
-def gen(n: int, k_bits: int):
-    a = [rand(k_bits) for _ in range(n)]
-    return a
-
-def b2b(b: bytes) -> list[int]:
-    out = []
-    for byte in b:
-        for i in range(8):
-            out.append((byte >> i) & 1)
-    return out
-
-def pack(bits) -> bytes:
-    out = bytearray()
-    for i in range(0, len(bits), 8):
-        chunk = bits[i:i+8]
-        val = 0
-        for j, bit in enumerate(chunk):
-            val |= (bit & 1) << j
-        out.append(val)
-    return bytes(out)
-
-def gen_key(x_bits: list[int], saltx: bytes, salty: bytes, length: int = 16) -> bytes:
-    material = pack(x_bits)
-    prk = hashlib.pbkdf2_hmac("sha256", material, saltx, 131072, dklen=32)
-    return hmac.new(prk, b"afk-players-wanted-now" + salty + b"\x01", hashlib.sha256).digest()[:length]
-
-def enc(k: bytes, data: bytes):
-    iv = os.urandom(16)
-    ct = AES.new(k, AES.MODE_CBC, iv).encrypt(pad(data, 16))
-    return iv, ct
-
-def add(a, x_bits) -> int:
-    return sum(ai for ai, xi in zip(a, x_bits) if xi)
-
-def main():
-    a = gen(n, k)
-    x_bits = b2b(flag)
-    if len(x_bits) < n:
-        x_bits += [rng.randrange(0, 2) for _ in range(n - len(x_bits))]
-    else:
-        x_bits = x_bits[:n]
-
-    s = add(a, x_bits)
-
-    saltx = os.urandom(16)
-    salty = os.urandom(16)
-    key = gen_key(x_bits, saltx, salty)
-
-    iv, ct = enc(key, flag)
-
-    header = {
-        "n": n,
-        "k_bits": k,
-    }
-    print(json.dumps(header, separators=(",", ":")), flush=True)
-
-    while True:
-        try:
-            print(menu, end="", flush=True)
-            line = sys.stdin.readline()
-            if not line:
-                break
-            try:
-                choice = int(line.strip())
-            except ValueError:
-                print("sheesh")
-                continue
-
-            if choice == 1:
-                print("data: ", end="", flush=True)
-                dline = sys.stdin.readline()
-                if not dline:
-                    break
-                try:
-                    data = bytes.fromhex(dline.strip())
-                except Exception:
-                    print("hmmm")
-                    continue
-                iv, ct = enc(key, data)
-                print(iv.hex())
-                print(ct.hex())
-
-            elif choice == 2:
-                print(json.dumps({"a": a}, separators=(",", ":")))
-                print(str(s))
-                print(saltx.hex())
-                print(salty.hex())
-                print(iv.hex())
-                print(ct.hex())
-
-            elif choice == 3:
-                print("bubay")
-                return
-
-            else:
-                print("tidak ada yang mustahil, hehehe")
-
-        except Exception:
-            print("zzz")
-
-if __name__ == "__main__":
-    main()

services/phew/dist/chall.py

@@ -1,126 +0,0 @@
-#!/usr/bin/env python3
-
-import os, sys, json, random, hashlib, hmac
-from Crypto.Cipher import AES
-from Crypto.Util.Padding import pad
-with open("/flag.txt", "rb") as f:
-    flag = f.read()
-
-menu = (
-    "1) encrypt\n"
-    "2) profit\n"
-    "3) nyerah\n"
-    ">> "
-)
-
-
-k = 1024  
-n = 169
-
-rng = random.SystemRandom()
-
-def rand(k_bits: int) -> int:
-    return rng.randrange(1, 1 << k_bits)
-
-def gen(n: int, k_bits: int):
-    a = [rand(k_bits) for _ in range(n)]
-    return a
-
-def b2b(b: bytes) -> list[int]:
-    out = []
-    for byte in b:
-        for i in range(8):
-            out.append((byte >> i) & 1)
-    return out
-
-def pack(bits) -> bytes:
-    out = bytearray()
-    for i in range(0, len(bits), 8):
-        chunk = bits[i:i+8]
-        val = 0
-        for j, bit in enumerate(chunk):
-            val |= (bit & 1) << j
-        out.append(val)
-    return bytes(out)
-
-def gen_key(x_bits: list[int], saltx: bytes, salty: bytes, length: int = 16) -> bytes:
-    material = pack(x_bits)
-    prk = hashlib.pbkdf2_hmac("sha256", material, saltx, 131072, dklen=32)
-    return hmac.new(prk, b"afk-players-wanted-now" + salty + b"\x01", hashlib.sha256).digest()[:length]
-
-def enc(k: bytes, data: bytes):
-    iv = os.urandom(16)
-    ct = AES.new(k, AES.MODE_CBC, iv).encrypt(pad(data, 16))
-    return iv, ct
-
-def add(a, x_bits) -> int:
-    return sum(ai for ai, xi in zip(a, x_bits) if xi)
-
-def main():
-    a = gen(n, k)
-    x_bits = b2b(flag)
-    if len(x_bits) < n:
-        x_bits += [rng.randrange(0, 2) for _ in range(n - len(x_bits))]
-    else:
-        x_bits = x_bits[:n]
-
-    s = add(a, x_bits)
-
-    saltx = os.urandom(16)
-    salty = os.urandom(16)
-    key = gen_key(x_bits, saltx, salty)
-
-    iv, ct = enc(key, flag)
-
-    header = {
-        "n": n,
-        "k_bits": k,
-    }
-    print(json.dumps(header, separators=(",", ":")), flush=True)
-
-    while True:
-        try:
-            print(menu, end="", flush=True)
-            line = sys.stdin.readline()
-            if not line:
-                break
-            try:
-                choice = int(line.strip())
-            except ValueError:
-                print("sheesh")
-                continue
-
-            if choice == 1:
-                print("data: ", end="", flush=True)
-                dline = sys.stdin.readline()
-                if not dline:
-                    break
-                try:
-                    data = bytes.fromhex(dline.strip())
-                except Exception:
-                    print("hmmm")
-                    continue
-                iv, ct = enc(key, data)
-                print(iv.hex())
-                print(ct.hex())
-
-            elif choice == 2:
-                print(json.dumps({"a": a}, separators=(",", ":")))
-                print(str(s))
-                print(saltx.hex())
-                print(salty.hex())
-                print(iv.hex())
-                print(ct.hex())
-
-            elif choice == 3:
-                print("bubay")
-                return
-
-            else:
-                print("tidak ada yang mustahil, hehehe")
-
-        except Exception:
-            print("zzz")
-
-if __name__ == "__main__":
-    main()

services/phew/docker-compose.yml

@@ -1,16 +0,0 @@
-version: "3.8"
-
-services:
-  phew:
-    container_name: phew_container
-    hostname: phew
-    restart: always
-    build:
-      context: .
-      args:
-        - PASSWORD=root
-    ports:
-      - "13000:8000"
-      - "13022:22"
-    environment:
-      - FLAG=GEMASTIK{local_flag}

services/phew/requirements.txt

@@ -1 +0,0 @@
-pycryptodome

services/phew/run.sh

@@ -1,3 +0,0 @@
-#!/bin/sh
-
-exec socat tcp-l:8000,reuseaddr,fork exec:"python3 ./chall.py"

services/phew/start.sh

@@ -1,25 +0,0 @@
-#!/bin/bash
-set -e
-
-ssh-keygen -A
-
-# Configure SSH
-grep -q "^PermitRootLogin" /etc/ssh/sshd_config && \
-  sed -i "s/^PermitRootLogin.*/PermitRootLogin no/" /etc/ssh/sshd_config || \
-  echo "PermitRootLogin no" >> /etc/ssh/sshd_config
-
-grep -q "^PasswordAuthentication" /etc/ssh/sshd_config && \
-  sed -i "s/^PasswordAuthentication.*/PasswordAuthentication yes/" /etc/ssh/sshd_config || \
-  echo "PasswordAuthentication yes" >> /etc/ssh/sshd_config
-
-echo "AllowUsers ctf" >> /etc/ssh/sshd_config
-
-/usr/sbin/sshd
-
-if [ -n "$FLAG" ]; then
-    echo "$FLAG" > /flag.txt
-    chmod 644 /flag.txt
-    chown root:root /flag.txt
-fi
-
-exec su -c "cd /home/ctf/chall/src && ./run.sh" -s /bin/bash ctf

services/sheesh/chall.py

@@ -1,116 +1,116 @@
 #!/usr/bin/env python3
 
-import os, sys, json, random, hashlib, hmac
+import os
+import binascii
+import hashlib
+import threading
+import time
+import sys
 from Crypto.Cipher import AES
-from Crypto.Util.Padding import pad
+from Crypto.Util.Padding import pad, unpad
-with open("/flag.txt", "rb") as f:
+
+seed_bits = 23
+seed_max  = 1 << seed_bits
+seed_len  = (seed_bits + 7) // 8
+key = os.urandom(16)
+
+def hash_seed(seed_int: int) -> bytes:
+    sb = seed_int.to_bytes(seed_len, "big")
+    return hashlib.sha256(sb).digest()[:16]
+
+seed  = int.from_bytes(os.urandom(4), "big") % seed_max
+seed2 = int.from_bytes(os.urandom(4), "big") % seed_max
+K1 = hash_seed(seed)
+K2 = hash_seed(seed2)
+
+with open("./flag.txt", "rb") as f:
     flag = f.read()
-    
-B = 16
-opts = (
-    "1) encrypt\n"
-    "2) profit\n"
-    "3) nyerah\n"
-    ">> "
-)
 
-def exp(prk: bytes, info: bytes, L: int) -> bytes:
+def read_hex(prompt: str):
-    return hmac.new(prk, info + b"\x01", hashlib.sha256).digest()[:L]
+    s = input(prompt).strip()
+    try:
+        return binascii.unhexlify(s)
+    except Exception:
+        print("hmm")
+        return None
 
-def enc(k: bytes, data: bytes):
+def enc_cfb(pt: bytes) -> bytes:
-    iv = os.urandom(B)
+    iv = os.urandom(16)
-    ct = AES.new(k, AES.MODE_CBC, iv).encrypt(pad(data, B))
+    aes = AES.new(key, AES.MODE_CFB, iv=iv, segment_size=128)
-    return iv, ct
+    ct = aes.encrypt(pt)
+    return iv + ct
 
-def inp_hex(prompt: str) -> bytes:
+def enc_cbc(data: bytes, iv1: bytes, iv2: bytes, padd: bool) -> bytes:
-    print(prompt, end="", flush=True)
+    x  = pad(data, 16) if padd else data
-    s = sys.stdin.readline()
+    c1 = AES.new(K1, AES.MODE_CBC, iv=iv1).encrypt(x)
-    if not s:
+    c2 = AES.new(K2, AES.MODE_CBC, iv=iv2).encrypt(c1)
-        raise EOFError
+    return c2
-    return bytes.fromhex(s.strip())
 
-def rand(rng, d, lo, hi):
+def menu():
-    while True:
+    print("""
-        v = [rng.randint(lo, hi) for _ in range(d)]
+1. encrypt 
-        if any(v):
+2. profit 
-            return v
+3. get third 
+4. exit
+    """)
 
-def syst(rng):
+third = 0
-    d = rng.choice([2, 3])
+iv11 = None
-    m = rng.randint(5, 8)
+iv22 = None
-    x = rand(rng, d, -3, 3)
-    rows = []
-    for _ in range(m):
-        base = rand(rng, d, -3, 3)
-        r = rng.randint(1, 7)
-        scaled = [r * a for a in base]
-        e = rng.randint(0, 1)
-        bi = sum(ai * xi for ai, xi in zip(scaled, x)) + e
-        rows.append((scaled, bi))
-    rng.shuffle(rows)
-    A = [row for (row, _) in rows]
-    B = [b for (_, b) in rows]
-    pub = {"dim": d, "A": A, "b": B}
-    return pub, tuple(x)
 
-def bundle():
+def alarm():
-    rng = random.Random(os.urandom(16))
+    time.sleep(180)
-    systems = []
+    print("zzz")
-    hidden = []
+    sys.exit(0)
-    for _ in range(4):
-        pub, x = syst(rng)
-        systems.append(pub)
-        hidden.append(x)
-    return {"systems": systems}, tuple(hidden)
 
-def get_key(saltx: bytes, salty: bytes, b):
+threading.Thread(target=alarm, daemon=True).start()
-    parts = []
-    for x in b:
-        parts.append(",".join(str(t) for t in x))
-    material = "|".join(parts).encode()
-    prk = hashlib.pbkdf2_hmac("sha256", material, saltx, 131072, dklen=32)
-    return exp(prk, b"g3m4zzzt1q" + salty, 16)
 
-def main():
+while True:
-    a, b = bundle()
+    menu()
-    print(json.dumps(a, separators=(",", ":")), flush=True)
+    op = input("> ").strip()
-    saltx = os.urandom(16)
-    salty   = os.urandom(16)
-    key = get_key(saltx, salty, b)
-    iv, ct = enc(key, flag)
-    while True:
-        try:
-            print(opts, end="", flush=True)
-            line = sys.stdin.readline()
-            if not line:
-                break
-            try:
-                choice = int(line.strip())
-            except ValueError:
-                print("sheesh")
-                continue
 
-            if choice == 1:
+    if op == "1":
-                data = inp_hex("data: ")
+        data = read_hex("pt: ")
-                iv, ct = enc(key, data)
+        if data is None:
-                print(iv.hex())
+            print()
-                print(ct.hex())
+            continue
+        out = enc_cfb(data)
+        print("ct: ", out.hex())
+        print()
 
-            elif choice == 2:
+    elif op == "2":
-                print(iv.hex())
+        if iv11 is not None and iv22 is not None:
-                print(ct.hex())
+            iv1, iv2 = iv11, iv22
-                print(saltx.hex())
+            iv11 = iv22 = None
-                print(salty.hex())
+        else:
+            iv1 = os.urandom(16)
+            iv2 = os.urandom(16)
+        ct  = enc_cbc(flag, iv1, iv2, padd=True)
+        print("iv1: ", iv1.hex())
+        print("iv2: ", iv2.hex())
+        print("ct: ", ct.hex())
+        print()
 
-            elif choice == 3:
+    elif op == "3":
-                print("bubay")
+        if third:
-                return
+            print("sheesh")
+            continue
+        block = read_hex("pt: ")
+        if block is None:
+            print()
+            continue
+        if len(block) != 16:
+            print("hmmm\n")
+            continue
+        iv1 = os.urandom(16)
+        iv2 = os.urandom(16)
+        ct  = enc_cbc(block, iv1, iv2, padd=False)
+        iv11, iv22 = iv1, iv2
+        print("ct: ", ct.hex())
+        third = 1
+        print()
 
-            else:
+    elif op == "4":
-                print("when you feel like quitting, remember why you started :v (yapping)")
+        break
-
+    else:
-        except Exception:
+        print("mabokkkk?")
-            print("zzz")
-
-if __name__ == "__main__":
-    main()

services/sheesh/dist/chall.py

@@ -1,116 +1,116 @@
 #!/usr/bin/env python3
 
-import os, sys, json, random, hashlib, hmac
+import os
+import binascii
+import hashlib
+import threading
+import time
+import sys
 from Crypto.Cipher import AES
-from Crypto.Util.Padding import pad
+from Crypto.Util.Padding import pad, unpad
-with open("/flag.txt", "rb") as f:
+
+seed_bits = 23
+seed_max  = 1 << seed_bits
+seed_len  = (seed_bits + 7) // 8
+key = os.urandom(16)
+
+def hash_seed(seed_int: int) -> bytes:
+    sb = seed_int.to_bytes(seed_len, "big")
+    return hashlib.sha256(sb).digest()[:16]
+
+seed  = int.from_bytes(os.urandom(4), "big") % seed_max
+seed2 = int.from_bytes(os.urandom(4), "big") % seed_max
+K1 = hash_seed(seed)
+K2 = hash_seed(seed2)
+
+with open("./flag.txt", "rb") as f:
     flag = f.read()
-    
-B = 16
-opts = (
-    "1) encrypt\n"
-    "2) profit\n"
-    "3) nyerah\n"
-    ">> "
-)
 
-def exp(prk: bytes, info: bytes, L: int) -> bytes:
+def read_hex(prompt: str):
-    return hmac.new(prk, info + b"\x01", hashlib.sha256).digest()[:L]
+    s = input(prompt).strip()
+    try:
+        return binascii.unhexlify(s)
+    except Exception:
+        print("hmm")
+        return None
 
-def enc(k: bytes, data: bytes):
+def enc_cfb(pt: bytes) -> bytes:
-    iv = os.urandom(B)
+    iv = os.urandom(16)
-    ct = AES.new(k, AES.MODE_CBC, iv).encrypt(pad(data, B))
+    aes = AES.new(key, AES.MODE_CFB, iv=iv, segment_size=128)
-    return iv, ct
+    ct = aes.encrypt(pt)
+    return iv + ct
 
-def inp_hex(prompt: str) -> bytes:
+def enc_cbc(data: bytes, iv1: bytes, iv2: bytes, padd: bool) -> bytes:
-    print(prompt, end="", flush=True)
+    x  = pad(data, 16) if padd else data
-    s = sys.stdin.readline()
+    c1 = AES.new(K1, AES.MODE_CBC, iv=iv1).encrypt(x)
-    if not s:
+    c2 = AES.new(K2, AES.MODE_CBC, iv=iv2).encrypt(c1)
-        raise EOFError
+    return c2
-    return bytes.fromhex(s.strip())
 
-def rand(rng, d, lo, hi):
+def menu():
-    while True:
+    print("""
-        v = [rng.randint(lo, hi) for _ in range(d)]
+1. encrypt 
-        if any(v):
+2. profit 
-            return v
+3. get third 
+4. exit
+    """)
 
-def syst(rng):
+third = 0
-    d = rng.choice([2, 3])
+iv11 = None
-    m = rng.randint(5, 8)
+iv22 = None
-    x = rand(rng, d, -3, 3)
-    rows = []
-    for _ in range(m):
-        base = rand(rng, d, -3, 3)
-        r = rng.randint(1, 7)
-        scaled = [r * a for a in base]
-        e = rng.randint(0, 1)
-        bi = sum(ai * xi for ai, xi in zip(scaled, x)) + e
-        rows.append((scaled, bi))
-    rng.shuffle(rows)
-    A = [row for (row, _) in rows]
-    B = [b for (_, b) in rows]
-    pub = {"dim": d, "A": A, "b": B}
-    return pub, tuple(x)
 
-def bundle():
+def alarm():
-    rng = random.Random(os.urandom(16))
+    time.sleep(180)
-    systems = []
+    print("zzz")
-    hidden = []
+    sys.exit(0)
-    for _ in range(4):
-        pub, x = syst(rng)
-        systems.append(pub)
-        hidden.append(x)
-    return {"systems": systems}, tuple(hidden)
 
-def get_key(saltx: bytes, salty: bytes, b):
+threading.Thread(target=alarm, daemon=True).start()
-    parts = []
-    for x in b:
-        parts.append(",".join(str(t) for t in x))
-    material = "|".join(parts).encode()
-    prk = hashlib.pbkdf2_hmac("sha256", material, saltx, 131072, dklen=32)
-    return exp(prk, b"g3m4zzzt1q" + salty, 16)
 
-def main():
+while True:
-    a, b = bundle()
+    menu()
-    print(json.dumps(a, separators=(",", ":")), flush=True)
+    op = input("> ").strip()
-    saltx = os.urandom(16)
-    salty   = os.urandom(16)
-    key = get_key(saltx, salty, b)
-    iv, ct = enc(key, flag)
-    while True:
-        try:
-            print(opts, end="", flush=True)
-            line = sys.stdin.readline()
-            if not line:
-                break
-            try:
-                choice = int(line.strip())
-            except ValueError:
-                print("sheesh")
-                continue
 
-            if choice == 1:
+    if op == "1":
-                data = inp_hex("data: ")
+        data = read_hex("pt: ")
-                iv, ct = enc(key, data)
+        if data is None:
-                print(iv.hex())
+            print()
-                print(ct.hex())
+            continue
+        out = enc_cfb(data)
+        print("ct: ", out.hex())
+        print()
 
-            elif choice == 2:
+    elif op == "2":
-                print(iv.hex())
+        if iv11 is not None and iv22 is not None:
-                print(ct.hex())
+            iv1, iv2 = iv11, iv22
-                print(saltx.hex())
+            iv11 = iv22 = None
-                print(salty.hex())
+        else:
+            iv1 = os.urandom(16)
+            iv2 = os.urandom(16)
+        ct  = enc_cbc(flag, iv1, iv2, padd=True)
+        print("iv1: ", iv1.hex())
+        print("iv2: ", iv2.hex())
+        print("ct: ", ct.hex())
+        print()
 
-            elif choice == 3:
+    elif op == "3":
-                print("bubay")
+        if third:
-                return
+            print("sheesh")
+            continue
+        block = read_hex("pt: ")
+        if block is None:
+            print()
+            continue
+        if len(block) != 16:
+            print("hmmm\n")
+            continue
+        iv1 = os.urandom(16)
+        iv2 = os.urandom(16)
+        ct  = enc_cbc(block, iv1, iv2, padd=False)
+        iv11, iv22 = iv1, iv2
+        print("ct: ", ct.hex())
+        third = 1
+        print()
 
-            else:
+    elif op == "4":
-                print("when you feel like quitting, remember why you started :v (yapping)")
+        break
-
+    else:
-        except Exception:
+        print("mabokkkk?")
-            print("zzz")
-
-if __name__ == "__main__":
-    main()