102 lines
2.4 KiB
Python
102 lines
2.4 KiB
Python
#!/usr/bin/env python3
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import os
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import binascii
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import hashlib
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from Crypto.Cipher import AES
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from Crypto.Util.Padding import pad, unpad
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seed_bits = 23
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seed_max = 1 << seed_bits
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seed_len = (seed_bits + 7) // 8
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key = os.urandom(16)
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def hash(seed_int: int) -> bytes:
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sb = seed_int.to_bytes(seed_len, "big")
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return hashlib.sha256(sb).digest()[:16]
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seed = int.from_bytes(os.urandom(4), "big") % seed_max
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seed2 = int.from_bytes(os.urandom(4), "big") % seed_max
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K1 = hash(seed)
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K2 = hash(seed2)
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with open("/flag.txt","rb") as f:
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FLAG = f.read()
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def read(prompt: str):
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s = input(prompt).strip()
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try:
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return binascii.unhexlify(s)
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except Exception:
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print("hmm")
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return None
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def enc_cfb(pt: bytes) -> bytes:
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iv = os.urandom(16)
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aes = AES.new(key, AES.MODE_CFB, iv=iv, segment_size=128)
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pt2 = pt + FLAG[:len(FLAG)//2]
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ct = aes.encrypt(pt2)
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return iv + ct
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def enc_cbc(data: bytes, iv1: bytes, iv2: bytes, padd: bool) -> bytes:
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x = pad(data, 16) if padd else data
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c1 = AES.new(K1, AES.MODE_CBC, iv=iv1).encrypt(x)
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c2 = AES.new(K2, AES.MODE_CBC, iv=iv2).encrypt(c1)
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return c2
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def menu():
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print("""
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1. encrypt
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2. profit
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3. get third
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4. exit
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""")
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third = 0
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while True:
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menu()
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op = input("> ").strip()
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if op == "1":
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data = read("pt: ")
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if data is None:
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print()
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continue
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out = enc_cfb(data)
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print("ct: ", out.hex())
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print()
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elif op == "2":
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iv1 = os.urandom(16)
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iv2 = os.urandom(16)
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ct = enc_cbc(FLAG, iv1, iv2, padd=True)
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print("iv1: ", iv1.hex())
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print("iv2: ", iv2.hex())
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print("ct: ", ct.hex())
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print()
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elif op == "3":
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if third:
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print("sheesh")
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continue
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block = read("pt: ")
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if block is None:
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print()
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continue
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if len(block) != 16:
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print("hmmm\n")
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continue
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iv1 = os.urandom(16)
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iv2 = os.urandom(16)
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ct = enc_cbc(block, iv1, iv2, padd=0)
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print("iv1: ", iv1.hex())
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print("iv2: ", iv2.hex())
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print("ct: ", ct.hex())
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third = 1
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print()
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elif op == "4":
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break
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else:
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print("mabokkkk?")
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