Use a secret code, also known as enciphering, is the process of transforming plain text into a coded form using a cipher. Enciphering is used to protect information from unauthorized access and to ensure its confidentiality. It is an important part of cryptography, which is the practice of secure communication. Enciphering involves substituting one letter for another or replacing a letter with a symbol or number. This makes it difficult for anyone who does not have the key to decipher the message.