What is an Encryption Algorithm?

• A. Hash Function
• B. Pseudorandom Generator
• C. Encryption Algorithm
• D. Data Compression

Answer: (C)

An encryption algorithm is a formal method that, with a secret key, converts readable data (plaintext) into unreadable data (ciphertext) and can reverse the process to recover the original data. This reversible transformation provides confidentiality because only someone with the correct key can decrypt and read the information. The other options don’t fit because a hash function produces a fixed-size digest and is designed to be one-way and non-reversible, so you can’t recover the original data from the digest. A pseudorandom generator outputs sequences of numbers that look random and may be used within encryption schemes, but it isn’t itself the method that encrypts and decrypts data. Data compression reduces size and has no security function.