Match each cryptographic algorithm to its type.
Drag a concept onto its matching description — or click a concept then click the description.
Symmetric block cipher
Asymmetric (public-key) cipher
Hash function
Keyed-hash message authentication code
Elliptic curve digital signature algorithm
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
RSA: Asymmetric encryption algorithm
RSA is asymmetric, AES is symmetric, SHA-256 is a hash, and HMAC is a MAC. The distractors incorrectly label RSA and SHA-256 as symmetric encryption.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
RSA: Asymmetric encryption algorithm
Why this is correct
RSA is a foundational asymmetric encryption algorithm that relies on a mathematically linked public and private key pair. The public key can encrypt data, but only the corresponding private key can decrypt it, ensuring confidentiality and enabling secure key exchange. This distinct key usage for different operations is the defining characteristic of asymmetric cryptography, also known as public-key cryptography.
AES: Symmetric encryption algorithm
Why this is correct
Advanced Encryption Standard (AES) is a highly secure and widely adopted symmetric block cipher, meaning it uses the identical secret key for both encrypting and decrypting data. Its efficiency and robust cryptographic strength make it the standard for protecting data at rest and in transit, particularly after a secure key exchange has been performed using asymmetric methods. AES operates on fixed-size blocks of data, transforming them through multiple rounds of substitutions and permutations.
SHA-256: Cryptographic hash function
Why this is correct
SHA-256 is a prominent member of the Secure Hash Algorithm family, functioning as a cryptographic hash function designed to produce a fixed-size, unique output (a hash or message digest) from any input data. This one-way mathematical process is computationally infeasible to reverse, making it ideal for verifying data integrity by detecting even minute alterations. Its 256-bit output ensures strong collision resistance, crucial for applications like digital signatures and password storage.
HMAC: Keyed-hash message authentication code
Why this is correct
A Keyed-Hash Message Authentication Code (HMAC) provides both data integrity and authenticity by combining a secret cryptographic key with a hash function, such as SHA-256. Unlike a simple hash, HMAC ensures that the message has not been tampered with and originates from a sender possessing the shared secret key. This mechanism prevents unauthorized modifications and spoofing, making it vital for secure communication protocols where message origin verification is paramount.
RSA: Symmetric encryption algorithm
Why it's wrong here
Classifying RSA as a symmetric encryption algorithm is incorrect because its fundamental design principle involves distinct keys for encryption and decryption. Symmetric algorithms, by definition, utilize the same secret key for both cryptographic operations, whereas RSA employs a mathematically linked public-private key pair. This architectural difference means RSA cannot function under the symmetric paradigm, which would compromise its security and intended use for key exchange and digital signatures.
SHA-256: Symmetric encryption algorithm
Why it's wrong here
Designating SHA-256 as a symmetric encryption algorithm is fundamentally mistaken, as SHA-256 is a cryptographic hash function, not an encryption method. Hash functions are one-way mathematical operations that produce a fixed-size output, primarily for data integrity verification, and are irreversible. Encryption, conversely, is a two-way process designed for confidentiality, where data can be transformed into an unreadable format and then reverted to its original state using a specific key.
Quick reference
| Algorithm | Key Size | Block Size | Status | Notes |
|---|---|---|---|---|
| AES-128 | 128-bit | 128-bit | Current standard | NIST approved; WPA3, TLS |
| AES-256 | 256-bit | 128-bit | Current standard | Preferred for sensitive / govt data |
| 3DES | 112-bit effective | 64-bit | Deprecated (2023) | Replaced by AES |
| DES | 56-bit | 64-bit | Broken | Cracked in < 24 h; never deploy |
| ChaCha20 | 256-bit | Stream cipher | Current | TLS 1.3, WireGuard |
Go deeper
Learn chapter
Asset Security: Privacy and Data Retention
Key term
Encryption
Encryption is the process of converting readable data into a secret code to prevent unauthorized access.
Key term
Symmetric encryption
Symmetric encryption is a cryptographic method where the same secret key is used to both encrypt and decrypt data, ensuring confidentiality between two parties.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CISSP practice question is part of Courseiva's free ISC2 certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CISSP exam.