说明：  HIll2密码求密钥。适用于已知明文攻击。 可求加密密钥和解密密钥。 使用时，只需输入对应的两组明文与密文对，即可求得密钥。 运行软件：MATLAB。
(HIll2 cipher for keys. It is applicable to known plaintext attacks. Encryption keys and decryption keys can be obtained. When using, only the corresponding two groups of plaintext and ciphertext pair are input, then the key can be obtained. Running software: MATLAB.)