What does the term "ciphertext" refer to?

Ciphertext refers to the encrypted version of plaintext data. When data is subjected to encryption, the original readable content, called plaintext, is transformed into an unreadable format using an encryption algorithm and a key. This resulting unreadable format is what is known as ciphertext. The primary purpose of converting plaintext into ciphertext is to protect the information from unauthorized access, ensuring that only those with the appropriate key can decrypt and access the original data.

Understanding this concept is crucial in the field of encryption because it highlights the fundamental transformation that occurs in the encryption process. The other options present concepts related to encryption, such as the original readable data (plaintext), the methods (algorithms) used to perform encryption, and the keys that facilitate the process. However, none accurately describe what ciphertext is, making the identification of ciphertext as the encrypted data the critical aspect of this question.