updated sheesh
This commit is contained in:
@@ -5,6 +5,7 @@ import time
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import re
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import os
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import binascii
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import secrets
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class Sheesh(Challenge):
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flag_location = 'flags/sheesh.txt'
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@@ -33,7 +34,7 @@ class Sheesh(Challenge):
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bufsize=0,
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)
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def _read_exact_line(self, proc, timeout=5.0):
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def _read_exact_line(self, proc, timeout=6.0):
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start = time.time()
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buf = []
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r = proc.stdout.read
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@@ -47,13 +48,13 @@ class Sheesh(Challenge):
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if ch == "\n":
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return "".join(buf)
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def _read_until_prompt(self, proc, token: str, timeout=5.0):
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def _read_until_prompt(self, proc, token: str, timeout=6.0):
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start = time.time()
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acc = []
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r = proc.stdout.read
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while True:
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if time.time() - start > timeout:
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raise TimeoutError(f"Timeout waiting for '{token}'")
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raise TimeoutError(f"Timeout waiting for '{token}'")inp
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ch = r(1)
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if ch == "" and proc.poll() is not None:
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raise RuntimeError("Process ended while waiting for prompt")
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@@ -72,6 +73,36 @@ class Sheesh(Challenge):
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assert self._HEX_RE.match(hx), f"{label} is not hex"
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return hx
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def test1(self, proc, b16_hex: str) -> str:
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assert len(b16_hex) == 32
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self._read_until_prompt(proc, "inp: ", timeout=6.0)
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self._send_line(proc, b16_hex)
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line = self._read_exact_line(proc, timeout=4.0)
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assert line.startswith("blk:"), "Expected blk: for 16-byte input"
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hx = self._expect_hex_field(line, "blk")
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# chall prints an extra blank line after blk:
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_ = self._read_exact_line(proc, timeout=4.0)
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return hx.lower()
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def test2(self, proc, iv_hex: str, ct_hex: str) -> str:
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self._read_until_prompt(proc, "inp: ", timeout=6.0)
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self._send_line(proc, iv_hex + ct_hex)
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ans = self._read_exact_line(proc, timeout=4.0).strip().lower()
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assert ans in ("ok", "zzz"), "Padding oracle did not return ok/zzz"
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return ans
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def test3(self, proc, iv_hex: str, ct_hex: str, trials=9) -> tuple[int, int, str]:
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ok_cnt = 0
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zzz_cnt = 0
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for _ in range(trials):
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ans = self.test2(proc, iv_hex, ct_hex)
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if ans == "ok":
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ok_cnt += 1
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else:
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zzz_cnt += 1
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final = "ok" if ok_cnt > zzz_cnt else "zzz"
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return ok_cnt, zzz_cnt, final
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def distribute(self, flag):
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try:
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os.makedirs(os.path.dirname(self.flag_location), exist_ok=True)
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@@ -90,7 +121,6 @@ class Sheesh(Challenge):
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def check(self):
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try:
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# parity check: host vs container flag
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with open(self.flag_location, 'r') as f:
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host_flag = f.read().strip()
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container_flag = self._read_container_flag()
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@@ -99,9 +129,9 @@ class Sheesh(Challenge):
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proc = self._spawn()
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line1 = self._read_exact_line(proc, timeout=5.0)
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line2 = self._read_exact_line(proc, timeout=5.0)
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blank = self._read_exact_line(proc, timeout=5.0)
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line1 = self._read_exact_line(proc, timeout=6.0)
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line2 = self._read_exact_line(proc, timeout=6.0)
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blank = self._read_exact_line(proc, timeout=6.0)
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assert line1.startswith("iv:") and line2.startswith("ct:"), "Missing banner"
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iv_hex = self._expect_hex_field(line1, "iv")
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ct_hex = self._expect_hex_field(line2, "ct")
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@@ -110,54 +140,36 @@ class Sheesh(Challenge):
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assert len(iv0) == 16 and len(ct0) >= 16 and len(ct0) % 16 == 0, "Bad banner sizes"
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self.logger.info("[ok] banner parsed")
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self._read_until_prompt(proc, "blob: ", timeout=5.0)
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block00 = "00" * 16
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blk1 = self.test1(proc, block00)
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blk2 = self.test1(proc, block00)
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blk3 = self.test1(proc, block00)
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assert blk1 == blk2 == blk3, "ECB-masked oracle not deterministic for same input"
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self.logger.info("[ok] blk determinism (3x same input)")
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qA = "00" * 16
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self._send_line(proc, qA)
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lA = self._read_exact_line(proc, timeout=3.0)
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assert lA.startswith("blk:"), "Expected blk: for 16-byte blob"
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blk1 = self._expect_hex_field(lA, "blk")
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_ = self._read_exact_line(proc, timeout=3.0)
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self._read_until_prompt(proc, "blob: ", timeout=5.0)
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self._send_line(proc, qA)
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lA2 = self._read_exact_line(proc, timeout=3.0)
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blk2 = self._expect_hex_field(lA2, "blk")
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_ = self._read_exact_line(proc, timeout=3.0)
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assert blk1 == blk2, "ECB-masked oracle not deterministic for same input"
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self.logger.info("[ok] blk determinism")
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self._read_until_prompt(proc, "blob: ", timeout=5.0)
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qB = "01" * 16
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self._send_line(proc, qB)
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lB = self._read_exact_line(proc, timeout=3.0)
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blk3 = self._expect_hex_field(lB, "blk")
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_ = self._read_exact_line(proc, timeout=3.0)
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assert blk3 != blk1, "ECB-masked oracle returned same block for different input"
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block01 = "01" * 16
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blk4 = self.test1(proc, block01)
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assert blk4 != blk1, "ECB-masked oracle returned same block for different input"
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self.logger.info("[ok] blk diversity")
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self._read_until_prompt(proc, "blob: ", timeout=5.0)
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self._send_line(proc, "zzzz") # invalid hex
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line_err = self._read_exact_line(proc, timeout=3.0)
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self._read_until_prompt(proc, "inp: ", timeout=6.0)
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self._send_line(proc, "zzzz") # invalid hex
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line_err = self._read_exact_line(proc, timeout=4.0)
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assert "err" in line_err.lower(), "Expected 'err' for non-hex input"
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self.logger.info("[ok] error handling on non-hex")
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maybe_hmmm = self._read_exact_line(proc, timeout=4.0).strip().lower()
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if "hmmm" not in maybe_hmmm:
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self.logger.warning(f"[warn] expected 'hmmm' after err, got: {maybe_hmmm!r}")
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self.logger.info("[ok] error handling on non-hex input")
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self._read_until_prompt(proc, "blob: ", timeout=5.0)
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self._send_line(proc, (iv_hex + ct_hex))
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ans1 = self._read_exact_line(proc, timeout=3.0).strip().lower()
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assert ans1 in ("ok", "no"), "Padding oracle did not return ok/no for iv||ct"
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self.logger.info(f"[ok] padding oracle responds ({ans1}) on banner bundle")
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ok_cnt, zzz_cnt, final = self.test3(proc, iv_hex, ct_hex, trials=9)
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self.logger.info(f"[ok] padding oracle responded on banner (ok={ok_cnt}, zzz={zzz_cnt}, final={final})")
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self._read_until_prompt(proc, "blob: ", timeout=5.0)
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iv_synth = os.urandom(16).hex()
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ct_synth = ("00" * (6 * 16))
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self._send_line(proc, iv_synth + ct_synth)
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ans2 = self._read_exact_line(proc, timeout=3.0).strip().lower()
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assert ans2 in ("ok", "no"), "Padding oracle did not return ok/no on synthetic 6-block ct"
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self.logger.info(f"[ok] padding oracle responds ({ans2}) on synthetic payload")
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self._read_until_prompt(proc, "blob: ", timeout=5.0)
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iv_synth = secrets.token_hex(16)
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ct_synth = "00" * (6 * 16) # 6 blocks
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ok_cnt2, zzz_cnt2, final2 = self.test3(proc, iv_synth, ct_synth, trials=9)
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self.logger.info(f"[ok] padding oracle responded on synthetic (ok={ok_cnt2}, zzz={zzz_cnt2}, final={final2})")
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self._read_until_prompt(proc, "inp: ", timeout=6.0)
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proc.kill()
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self.logger.info('Check passed for sheesh')
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return True
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Vendored
+52
-51
@@ -1,80 +1,77 @@
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#!/usr/bin/env python3
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import os, sys, signal, binascii, random
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import os, sys, binascii, random
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from Crypto.Cipher import AES
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from Crypto.Util.Padding import pad, unpad
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from Crypto.Util.number import bytes_to_long, long_to_bytes
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random.seed(os.urandom(16))
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K0 = os.urandom(16)
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K1 = os.urandom(16)
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S0 = os.urandom(16)
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S1 = os.urandom(16)
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M0 = os.urandom(16)
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M1 = os.urandom(16)
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k0 = os.urandom(16)
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k1 = os.urandom(16)
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s0 = os.urandom(16); S1 = os.urandom(16)
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m0 = os.urandom(16); M1 = os.urandom(16)
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with open("/flag.txt","rb") as f:
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flag = f.read()
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def hex_input(q):
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s = input(q).strip()
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try: return binascii.unhexlify(s)
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try: return binascii.unhexlify(s)
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except: print("err"); return None
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def enc1(b16: bytes) -> bytes:
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x = AES.new(K1, AES.MODE_ECB).encrypt(b16)
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return bytes(a ^ b for a, b in zip(x, b16))
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def xex(b16):
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x = AES.new(k1, AES.MODE_ECB).encrypt(b16)
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return bytes(a ^ b for a,b in zip(x, b16))
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def enc2(iv: bytes, m: bytes) -> bytes:
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return AES.new(K0, AES.MODE_CBC, iv=iv).encrypt(pad(m, 16))
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def enc1(iv, msg):
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return AES.new(k0, AES.MODE_CBC, iv=iv).encrypt(pad(msg,16))
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def enc3(m: bytes) -> bytes:
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return AES.new(K1, AES.MODE_CBC, iv=b"\x00"*16).encrypt(pad(m, 16))[-16:]
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def dec1(iv, c):
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return unpad(AES.new(k0, AES.MODE_CBC, iv=iv).decrypt(c), 16)
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def T(iv: bytes, ct: bytes):
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def enc2(msg):
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return AES.new(k1, AES.MODE_CBC, iv=b"\x00"*16).encrypt(pad(msg,16))[-16:]
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def F(iv, ct):
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n = len(ct)
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if n < 96 or (n & 15):
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return None
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v = memoryview(ct)
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W = [bytes(v[i:i+16]) for i in range(0, n, 16)]
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if n < 96 or (n & 15): return None
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W = [ct[i:i+16] for i in range(0, n, 16)]
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m = len(W)
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r = ((iv[0] & 7) + 2) % m
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if r:
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W = W[r:] + W[:r]
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digest = enc2(iv)
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r = ((iv[0]^iv[-1]) & 7) + 2
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r %= m
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if r: W = W[r:] + W[:r]
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j = 1 + (W[0][0] & 1)
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if len(W) <= j:
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return None
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del W[j]
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if len(W) < 2:
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return None
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if len(W) < 3: return None
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A0 = long_to_bytes(bytes_to_long(W[0]) ^ bytes_to_long(m0))
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A1 = long_to_bytes(bytes_to_long(W[1]) ^ bytes_to_long(M1))
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j = 1 + (digest[0] & 1)
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del W[j]
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if len(W) < 2: return None
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a0 = long_to_bytes(bytes_to_long(W[0]) ^ bytes_to_long(M0))
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a1 = long_to_bytes(bytes_to_long(W[1]) ^ bytes_to_long(M1))
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return b"".join((S0, a0, S1, a1, *W[2:]))
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return b"".join((s0, A0, S1, A1, *W[2:]))
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def C(iv: bytes, ct: bytes) -> bool:
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z = T(iv, ct)
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def O(iv, ct):
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z = F(iv, ct)
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if z is None:
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ok = False
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else:
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try:
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x = AES.new(K0, AES.MODE_CBC, iv=iv).decrypt(z)
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unpad(x, 16)
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dec1(iv, z)
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ok = True
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except:
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ok = False
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if random.random() < 0.08:
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if random.random() < 0.10:
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ok = not ok
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return ok
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iv = os.urandom(16)
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MK = enc3(iv + iv)
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H0 = (flag + b"\x00"*16)[:16]
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H1 = bytes(a ^ b for a, b in zip(H0, MK))
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pt = H1 + flag[16:]
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ct = enc2(iv, pt)
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MK = enc2(iv + iv)
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h0 = (flag + b"\x00"*16)[:16]
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h1 = bytes(a ^ b for a,b in zip(h0, MK))
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pt = h1 + flag[16:]
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ct = enc1(iv, pt)
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print("iv:", iv.hex())
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print("ct:", ct.hex())
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@@ -82,17 +79,21 @@ print()
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while True:
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try:
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blob = hex_input("blob: ")
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if blob is None:
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print("err\n"); continue
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L = len(blob)
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if L == 16:
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y = enc1(blob)
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inp = hex_input("inp: ")
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if inp is None:
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print("hmmm\n"); continue
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L = len(inp)
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if L == 16:
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y = xex(inp)
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print("blk:", y.hex()); print()
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elif L >= 32 and (L % 16) == 0:
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iv, ct = blob[:16], blob[16:]
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print("ok\n" if C(iv, ct) else "no\n")
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ivq, ctq = inp[:16], inp[16:]
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print("ok\n" if O(ivq, ctq) else "zzz\n")
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else:
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print("err\n")
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print("hmmm\n")
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except EOFError:
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break
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@@ -1,80 +1,77 @@
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#!/usr/bin/env python3
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import os, sys, signal, binascii, random
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import os, sys, binascii, random
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from Crypto.Cipher import AES
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from Crypto.Util.Padding import pad, unpad
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from Crypto.Util.number import bytes_to_long, long_to_bytes
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random.seed(os.urandom(16))
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K0 = os.urandom(16)
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K1 = os.urandom(16)
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S0 = os.urandom(16)
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S1 = os.urandom(16)
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M0 = os.urandom(16)
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M1 = os.urandom(16)
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k0 = os.urandom(16)
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k1 = os.urandom(16)
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s0 = os.urandom(16); S1 = os.urandom(16)
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m0 = os.urandom(16); M1 = os.urandom(16)
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with open("/flag.txt","rb") as f:
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flag = f.read()
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def hex_input(q):
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s = input(q).strip()
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try: return binascii.unhexlify(s)
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try: return binascii.unhexlify(s)
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except: print("err"); return None
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def enc1(b16: bytes) -> bytes:
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x = AES.new(K1, AES.MODE_ECB).encrypt(b16)
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return bytes(a ^ b for a, b in zip(x, b16))
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def xex(b16):
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x = AES.new(k1, AES.MODE_ECB).encrypt(b16)
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return bytes(a ^ b for a,b in zip(x, b16))
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def enc2(iv: bytes, m: bytes) -> bytes:
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return AES.new(K0, AES.MODE_CBC, iv=iv).encrypt(pad(m, 16))
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def enc1(iv, msg):
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return AES.new(k0, AES.MODE_CBC, iv=iv).encrypt(pad(msg,16))
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def enc3(m: bytes) -> bytes:
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return AES.new(K1, AES.MODE_CBC, iv=b"\x00"*16).encrypt(pad(m, 16))[-16:]
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def dec1(iv, c):
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return unpad(AES.new(k0, AES.MODE_CBC, iv=iv).decrypt(c), 16)
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def T(iv: bytes, ct: bytes):
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def enc2(msg):
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return AES.new(k1, AES.MODE_CBC, iv=b"\x00"*16).encrypt(pad(msg,16))[-16:]
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def F(iv, ct):
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n = len(ct)
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if n < 96 or (n & 15):
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return None
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v = memoryview(ct)
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W = [bytes(v[i:i+16]) for i in range(0, n, 16)]
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if n < 96 or (n & 15): return None
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W = [ct[i:i+16] for i in range(0, n, 16)]
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m = len(W)
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r = ((iv[0] & 7) + 2) % m
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if r:
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W = W[r:] + W[:r]
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digest = enc2(iv)
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r = ((iv[0]^iv[-1]) & 7) + 2
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r %= m
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if r: W = W[r:] + W[:r]
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j = 1 + (W[0][0] & 1)
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if len(W) <= j:
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return None
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del W[j]
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if len(W) < 2:
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return None
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if len(W) < 3: return None
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A0 = long_to_bytes(bytes_to_long(W[0]) ^ bytes_to_long(m0))
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A1 = long_to_bytes(bytes_to_long(W[1]) ^ bytes_to_long(M1))
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j = 1 + (digest[0] & 1)
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del W[j]
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if len(W) < 2: return None
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|
||||
a0 = long_to_bytes(bytes_to_long(W[0]) ^ bytes_to_long(M0))
|
||||
a1 = long_to_bytes(bytes_to_long(W[1]) ^ bytes_to_long(M1))
|
||||
return b"".join((S0, a0, S1, a1, *W[2:]))
|
||||
return b"".join((s0, A0, S1, A1, *W[2:]))
|
||||
|
||||
def C(iv: bytes, ct: bytes) -> bool:
|
||||
z = T(iv, ct)
|
||||
def O(iv, ct):
|
||||
z = F(iv, ct)
|
||||
if z is None:
|
||||
ok = False
|
||||
else:
|
||||
try:
|
||||
x = AES.new(K0, AES.MODE_CBC, iv=iv).decrypt(z)
|
||||
unpad(x, 16)
|
||||
dec1(iv, z)
|
||||
ok = True
|
||||
except:
|
||||
ok = False
|
||||
if random.random() < 0.08:
|
||||
if random.random() < 0.10:
|
||||
ok = not ok
|
||||
return ok
|
||||
|
||||
iv = os.urandom(16)
|
||||
MK = enc3(iv + iv)
|
||||
H0 = (flag + b"\x00"*16)[:16]
|
||||
H1 = bytes(a ^ b for a, b in zip(H0, MK))
|
||||
pt = H1 + flag[16:]
|
||||
ct = enc2(iv, pt)
|
||||
MK = enc2(iv + iv)
|
||||
h0 = (flag + b"\x00"*16)[:16]
|
||||
h1 = bytes(a ^ b for a,b in zip(h0, MK))
|
||||
pt = h1 + flag[16:]
|
||||
ct = enc1(iv, pt)
|
||||
|
||||
print("iv:", iv.hex())
|
||||
print("ct:", ct.hex())
|
||||
@@ -82,17 +79,21 @@ print()
|
||||
|
||||
while True:
|
||||
try:
|
||||
blob = hex_input("blob: ")
|
||||
if blob is None:
|
||||
print("err\n"); continue
|
||||
L = len(blob)
|
||||
if L == 16:
|
||||
y = enc1(blob)
|
||||
inp = hex_input("inp: ")
|
||||
if inp is None:
|
||||
print("hmmm\n"); continue
|
||||
L = len(inp)
|
||||
|
||||
if L == 16:
|
||||
y = xex(inp)
|
||||
print("blk:", y.hex()); print()
|
||||
|
||||
elif L >= 32 and (L % 16) == 0:
|
||||
iv, ct = blob[:16], blob[16:]
|
||||
print("ok\n" if C(iv, ct) else "no\n")
|
||||
ivq, ctq = inp[:16], inp[16:]
|
||||
print("ok\n" if O(ivq, ctq) else "zzz\n")
|
||||
|
||||
else:
|
||||
print("err\n")
|
||||
print("hmmm\n")
|
||||
|
||||
except EOFError:
|
||||
break
|
||||
|
||||
Reference in New Issue
Block a user