1. The message was encrypted using a secret key, and the result is a ciphertext that cannot be easily understood.
这条消息使用一个秘密密钥进行加密，结果是一个无法轻易理解的密文。

2. Cryptographers are experts in deciphering ciphertext and breaking encryption algorithms.
密码学家是专家，擅长解密密文和破译加密算法。