SSCP Cryptography Practice Question

A security engineer needs to choose an asymmetric algorithm for a system with limited computational resources, such as an IoT device. The algorithm must provide equivalent security to RSA 2048-bit while using smaller key sizes. Which algorithm should they choose?

⚠ Common exam trap

The SSCP exam often tests the misconception that larger key sizes always mean stronger security, leading candidates to pick RSA 2048-bit or Diffie-Hellman 2048-bit, while the trap is that ECC with much smaller key sizes (e.g., 256-bit) provides equivalent security with lower computational overhead, which is the exact requirement for IoT devices.

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

✓

Elliptic Curve Cryptography (ECC) with 256-bit keys

Elliptic Curve Cryptography (ECC) with 256-bit keys provides equivalent security to RSA 2048-bit because the elliptic curve discrete logarithm problem is significantly harder to solve than the integer factorization problem for the same key length. This allows ECC to achieve strong security with much smaller key sizes, making it ideal for resource-constrained IoT devices where memory, power, and processing are limited.

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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RSA with 2048-bit keys
Why it's wrong here
RSA with 2048-bit keys is the baseline the scenario seeks to improve on, so it delivers no key-size reduction for constrained hardware. It is tempting because RSA 2048 is the reference security level, and would be correct where ample computation exists and interoperability with legacy systems matters most.
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Elliptic Curve Cryptography (ECC) with 256-bit keys
Why this is correct
ECC achieves equivalent security with far smaller keys because its security rests on the elliptic curve discrete logarithm problem, which resists known sub-exponential attacks. A 256-bit ECC key matches RSA 2048-bit strength, satisfying the IoT constraint of limited computational resources and smaller key sizes.
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Diffie-Hellman with 2048-bit keys
Why it's wrong here
Diffie-Hellman with 2048-bit keys is a key-agreement method, not an encryption or signature algorithm, and its key sizes match RSA rather than shrinking. It is tempting because DH is asymmetric and widely deployed, and would be correct for establishing a shared secret over an untrusted channel, not for signing or encrypting IoT data.
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3DES with 168-bit keys
Why it's wrong here
3DES is a symmetric block cipher, not asymmetric, and its 168-bit keys provide no public-key exchange for an IoT device. It is tempting because 3DES is a recognised encryption standard with short keys, and would be correct for bulk data confidentiality where a shared secret already exists, not for key agreement.

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

SSCP Cryptography Practice Question

Why each option matters

Option-by-option breakdown

Symmetric Encryption Algorithm Comparison

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