What is an Encryption Algorithm?

• A. Also called "cryptographic algorithm." A sequence of mathematical instructions used for transforming unencrypted text or data to encrypted text or data, and back again.
• B. A hardware device that accelerates encryption
• C. A policy for data retention
• D. A type of firewall rule

Answer: (A)

An encryption algorithm is a cryptographic algorithm—a defined set of mathematical steps used to transform readable data into unreadable ciphertext and then back again using a key. This reversible process is what makes encryption possible: authorized parties can recover the original data with the correct key, while others cannot without it. There are two main families: symmetric algorithms use the same key for encryption and decryption, while asymmetric algorithms use a public key to encrypt and a private key to decrypt. The other options describe a hardware device that speeds up encryption, a policy document about data retention, or a firewall rule—none of which perform the data transformation defined by an encryption algorithm.