What is plaintext?

• A. The original readable message before encryption
• B. The encrypted message
• C. The key used for encryption
• D. The compressed data

Answer: (A)

Plaintext is the original readable data that you start with before any encryption is applied. It’s the content you want to protect, such as a message or document, in its plain, understandable form. When you encrypt plaintext, the algorithm turns it into ciphertext, which looks like random data and isn’t readable without the right key. That’s why the correct choice is the one that identifies plaintext as the original readable message before encryption. The encrypted message is the ciphertext, not plaintext. The key is the secret used to perform the encryption and decryption, not the content itself. Compressed data isn’t what plaintext refers to, though data could be compressed prior to encryption; plaintext specifically means the unencrypted content.