CEH Practice Question: Advanced Topics: Wireless, Cloud, IoT, Cryptography
Which TWO of the following are characteristics of symmetric encryption? (Select two)
⚠ Common exam trap
CEH often tests whether candidates can distinguish symmetric from asymmetric properties, so it swaps characteristics (speed, key structure, non-repudiation) between the two to catch those who memorize definitions without understanding the trade-offs.
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
✓
Uses a single shared key for encryption and decryption
Option A is correct because symmetric encryption is defined by the use of one single shared secret key that both encrypts and decrypts the data, unlike asymmetric algorithms that use a key pair. Option B is correct because symmetric ciphers such as AES and 3DES perform far fewer computationally expensive operations than asymmetric algorithms like RSA or ECC, making them significantly faster and better suited for bulk data encryption. Option C is incorrect because it reverses the actual performance relationship; symmetric encryption is faster, not slower, than asymmetric encryption. Option D is incorrect because non-repudiation requires a private key known only to one party, which is a property of asymmetric cryptography, not shared-key symmetric encryption. Option E is incorrect because a public/private key pair describes asymmetric encryption, whereas symmetric encryption relies on a single shared key.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Uses a single shared key for encryption and decryption
Why this is correct
Symmetric encryption algorithms, such as AES or DES, fundamentally rely on a singular, identical secret key for both the transformation of plaintext into ciphertext and the subsequent reversal of ciphertext back into plaintext. This shared secret must be securely exchanged between communicating parties prior to any encrypted data transmission. The efficiency of this method stems from using the same cryptographic key for both operations, simplifying key management for individual sessions.
- ✓
Faster than asymmetric encryption
Why this is correct
Symmetric encryption algorithms are significantly faster and more efficient in terms of computational overhead compared to their asymmetric counterparts. This speed advantage arises because symmetric algorithms typically involve simpler mathematical operations, making them ideal for encrypting large volumes of data. The reduced processing power required allows for higher throughput and lower latency in secure communications.
- ✗
Slower than asymmetric encryption
Why it's wrong here
This statement is incorrect because symmetric encryption algorithms are, in fact, considerably faster than asymmetric encryption algorithms. Symmetric methods utilize less complex mathematical operations, requiring fewer computational resources to encrypt and decrypt data. Consequently, they are preferred for bulk data encryption where high performance and throughput are critical, making them demonstrably quicker.
- ✗
Provides non-repudiation
Why it's wrong here
Symmetric encryption does not inherently provide non-repudiation, which is the assurance that a sender cannot deny having sent a message. Since both the sender and receiver possess the identical shared secret key, either party could theoretically have generated the ciphertext. Non-repudiation is typically achieved through asymmetric cryptography, specifically using digital signatures where the sender's unique private key creates a verifiable signature.
- ✗
Uses a pair of public and private keys
Why it's wrong here
This characteristic describes asymmetric encryption, not symmetric encryption. Asymmetric cryptography, also known as public-key cryptography, employs a mathematically linked pair of keys: a public key for encryption and a private key for decryption. Symmetric encryption, by contrast, relies solely on a single, identical secret key for both cryptographic operations, making this statement fundamentally incorrect for symmetric systems.
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 |
Go deeper
Related to this question
About these practice questions
Courseiva writes every CEH question from scratch — 913 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official EC-Council exam blueprint
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.