密码一种密码系统，其中固定长度的明文里的单元，通常为字母，被任意倒置或按事先确定的符号系统替换 A cryptographic system in which units of plain text of regular length, usually letters, are arbitrarily transposed or substituted according to a predetermined code.
加密员使用、研究或改进密码系统和密码书写的人 One who uses, studies, or develops cryptographic systems and writings.
