CEH Practice Question: Advanced Topics: Wireless, Cloud, IoT, Cryptography
Which of the following cryptographic algorithms is classified as asymmetric?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
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RSA
Asymmetric cryptography uses key pairs (public and private). RSA is a well-known asymmetric algorithm. AES, 3DES, and RC4 are symmetric algorithms.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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RC4
Why it's wrong here
RC4 is a symmetric stream cipher, meaning it encrypts data bit by bit or byte by byte using a single, shared secret key for both encryption and decryption. Its classification as symmetric, requiring the same key for both operations, directly contrasts with asymmetric algorithms that utilize distinct public and private keys. Therefore, RC4 does not fit the criteria for an asymmetric cryptographic algorithm.
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3DES
Why it's wrong here
Triple DES (3DES) is a symmetric block cipher that applies the Data Encryption Standard (DES) algorithm three times to each data block, typically using two or three distinct keys. Despite its multiple key usage, 3DES remains a symmetric algorithm because the same set of keys used for encryption must also be used, in reverse order, for decryption. This shared-key characteristic fundamentally distinguishes it from asymmetric cryptography.
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RSA
Why this is correct
RSA is a foundational asymmetric cryptographic algorithm, distinguished by its use of a mathematically linked public and private key pair. The public key can be freely distributed for encryption or signature verification, while the private key is kept secret for decryption or digital signing. This unique key separation allows for secure communication and authentication without prior key exchange, making it the correct classification.
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AES
Why it's wrong here
The Advanced Encryption Standard (AES) is a widely adopted symmetric block cipher, processing fixed-size blocks of data using a single, secret key for both encryption and decryption. Its strength lies in its robust mathematical design and variable key lengths (128, 192, or 256 bits), but its reliance on a shared secret key for both operations firmly places it in the symmetric category. Consequently, AES is not an asymmetric algorithm.
Quick reference
Symmetric Encryption Algorithm Comparison
| 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 |
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CEH practice question is part of Courseiva's free EC-Council 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 CEH exam.