What is the practice of creating secure messages?

• A. Cryptography
• B. Substitution Cipher
• C. Transposition Cipher
• D. DDoS

Answer: (A)

Cryptography is the practice of creating secure messages—transforming readable information into ciphertext so only authorized parties can read it, and then converting it back to plaintext. This relies on algorithms and keys to encrypt and decrypt, providing confidentiality and often supporting integrity and authentication through techniques like digital signatures and hashes. Substitution and transposition ciphers are classic methods used within cryptography to hide content, but the broader field encompasses many modern approaches beyond those specific techniques. DDoS is unrelated to securing messages, as it targets overwhelming a service rather than protecting communication.