CEH Practice Question: Advanced Topics: Wireless, Cloud, IoT, Cryptography
Which TWO of the following are symmetric encryption algorithms? (Select 2)
⚠ Common exam trap
CEH often tests the confusion between symmetric encryption, asymmetric encryption, and hashing by mixing algorithms like RSA, ECC, and MD5 into the same option list, so candidates must instantly classify each algorithm by its key model.
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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3DES
3DES (Triple DES) is correct because it is a symmetric block cipher that applies the DES algorithm three times with keys, using the same secret key for both encryption and decryption. AES (Advanced Encryption Standard) is correct because it is a symmetric block cipher that uses a single shared secret key for encryption and decryption, with key sizes of 128, 192, or 256 bits. ECC (Elliptic Curve Cryptography) is not correct because it is an asymmetric public-key algorithm based on elliptic curve mathematics. RSA is not correct because it is an asymmetric algorithm using a public/private key pair. MD5 is not correct because it is a cryptographic hash function, not an encryption algorithm.
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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ECC
Why it's wrong here
Elliptic Curve Cryptography (ECC) is an asymmetric encryption algorithm that relies on the mathematical properties of elliptic curves over finite fields. It uses a pair of mathematically linked keys, a public key for encryption and a private key for decryption, making it fundamentally different from symmetric algorithms. ECC is primarily employed for digital signatures and key exchange, offering strong security with smaller key sizes compared to other asymmetric methods.
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RSA
Why it's wrong here
RSA, named after Rivest, Shamir, and Adleman, is a widely adopted asymmetric encryption algorithm based on the computational difficulty of factoring large prime numbers. It utilizes distinct public and private keys, where the public key encrypts data and the private key decrypts it. Consequently, RSA is not a symmetric algorithm, as symmetric methods use a single shared secret key for both encryption and decryption processes.
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3DES
Why this is correct
Triple DES (3DES) is a symmetric block cipher that applies the original Data Encryption Standard (DES) algorithm three times to each data block. It uses either two or three distinct keys to significantly enhance security beyond single DES, making it a more robust, albeit slower, symmetric encryption method. As a symmetric algorithm, 3DES employs the same key for both encryption and decryption operations.
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AES
Why this is correct
The Advanced Encryption Standard (AES) is a symmetric block cipher adopted by the U.S. government and widely used globally for securing sensitive data. It operates on fixed-size blocks of data using a single, shared secret key for both encryption and decryption. AES supports key sizes of 128, 192, or 256 bits, offering strong security and high performance, making it the preferred symmetric algorithm for modern applications.
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MD5
Why it's wrong here
MD5 (Message-Digest Algorithm 5) is a cryptographic hash function, not an encryption algorithm. It takes an input message of any length and produces a fixed-size, 128-bit hash value, or "fingerprint," that is designed to be unique for each input. Unlike encryption, MD5 is a one-way function, meaning it cannot be reversed to retrieve the original data, and it is now considered cryptographically broken due to collision vulnerabilities.
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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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.