走进 Intel SGX：给数据造一间“金库密室”

import hashlibimport osfrom dataclasses import dataclassfrom typing import Optional  AES_BLOCK = 16  @dataclassclass SealedData:    """模拟 SGX 密封后的数据结构"""    ciphertext: bytes    tag: bytes    mrenclave: str  class Enclave:    """模拟一个 SGX 密室"""     def __init__(self, code: bytes, seal_key: bytes):        self.code = code        self.seal_key = seal_key        self._mrenclave = hashlib.sha256(code).hexdigest()        self.destroyed = False     @property    def mrenclave(self) -> str:        """返加密室指纹"""        return self._mrenclave     def ecall_verify_password(self, username: str, offset: int, length: int) -> bool:        """模拟 ECALL 入口：带边界检查的密码验证"""        # ---- 边界检查：模拟 SGX 对指针偏移和长度的校验 ----        if offset < 0 or length < 0 or offset + length > len(self.code):            return False  # 参数越界，拒绝执行        # ---- 真正的密室逻辑 ----        if username == "alice" and length == 8:            chunk = self.code[offset:offset + length]            if hashlib.sha256(chunk).hexdigest() == self._mrenclave[:8]:                return True        return False     def seal(self, plaintext: bytes) -> SealedData:        """数据密封：用 XOR 模拟 AES-GCM 加密，附认证标签"""        if self.destroyed:            raise RuntimeError("enclave 已销毁")        key_stream = b""        while len(key_stream) < len(plaintext):            key_stream += hashlib.sha256(self.seal_key + str(len(key_stream)).encode()).digest()        key_stream = key_stream[:len(plaintext)]        ciphertext = bytes(a ^ b for a, b in zip(plaintext, key_stream))        tag = hashlib.sha256(ciphertext + self._mrenclave.encode()).digest()[:8]        return SealedData(ciphertext=ciphertext, tag=tag, mrenclave=self._mrenclave)     def unseal(self, sealed: SealedData) -> Optional[bytes]:        """解封：验证 Ciphertext 完整性后还原明文"""        expect_tag = hashlib.sha256(sealed.ciphertext + self._mrenclave.encode()).digest()[:8]        if sealed.tag != expect_tag or sealed.mrenclave != self._mrenclave:            return None  # 数据被篡改或指纹不匹配        key_stream = b""        while len(key_stream) < len(sealed.ciphertext):            key_stream += hashlib.sha256(self.seal_key + str(len(key_stream)).encode()).digest()        key_stream = key_stream[:len(sealed.ciphertext)]        return bytes(a ^ b for a, b in zip(sealed.ciphertext, key_stream))  class SecretVault:    """模拟一个依赖 Enclave 的应用"""     def __init__(self):        self.enclave = Enclave(            code=b"DEFENDER_SECRET_MATERIAL" + os.urandom(32),            seal_key=os.urandom(16)        )     def authenticate(self, username: str, info: bytes, offset: int, length: int) -> bool:        """相当于 App 侧调用 ECALL 代理"""        return self.enclave.ecall_verify_password(username, offset, length)     def persist_secret(self, secret: bytes) -> SealedData:        """把机密数据密封后存到非安全区"""        return self.enclave.seal(secret)     def load_secret(self, sealed: SealedData) -> Optional[bytes]:        """从非安全区读取并解封"""        return self.enclave.unseal(sealed)  def main():    vault = SecretVault()    print("密室指纹(MRENCLAVE):", vault.enclave.mrenclave[:16], "...")    # 1. 合法的 ECALL 调用    offset = vault.enclave.code.index(b"SECRET_MATERIAL")    ok = vault.authenticate("alice", b"whatever", offset, 8)    print("合法 ECALL 验证:", "通过" if ok else "拒绝")    # 2. 非法的越界 ECALL 调用（试图越界读取）    bad = vault.authenticate("alice", b"whatever", -1, 9999)    print("越界 ECALL 验证:", "通过" if bad else "拒绝")    # 3. 密封持久化    sealed = vault.persist_secret(b"AI-Model-Weights-2025")    print("密封后数据:", sealed.ciphertext.hex()[:32], "... tag =", sealed.tag.hex())    original = vault.load_secret(sealed)    print("解封还原:", original.decode() if original else "失败")    # 4. 篡改密文（模拟磁盘数据被黑客修改）    tampered = SealedData(        ciphertext=sealed.ciphertext[:-1] + bytes([sealed.ciphertext[-1] ^ 1]),        tag=sealed.tag,        mrenclave=sealed.mrenclave    )    print("密文被篡改后解封:", vault.load_secret(tampered))  if __name__ == "__main__":    main()