The correct answer is that ECDHE provides perfect forward secrecy, a property that RSA key exchange lacks. This is because ECDHE generates a unique, ephemeral session key for each TLS session using elliptic curve Diffie-Hellman, so even if an attacker later obtains the server’s long-term private key, they cannot decrypt past recorded sessions. In contrast, RSA key exchange encrypts the session key with the server’s static public key, meaning a compromised private key exposes all historical traffic. On the SSCP exam, this concept tests your understanding of cryptographic protocols and secure communications, often appearing in questions about TLS hardening or cipher suite selection. A common trap is confusing key exchange with encryption; remember that PFS is about protecting past sessions, not just current ones. Memory tip: think “E” for Ephemeral equals “E” for Every session gets its own key—once gone, it’s gone for good.
SSCP Cryptography Practice Question
This SSCP practice question tests your understanding of cryptography. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A security analyst reviews the TLS configuration of a web server and notices that the cipher suite TLS_RSA_WITH_AES_128_CBC_SHA is enabled. The analyst recommends disabling RSA key exchange and enabling ECDHE. Which security property does ECDHE provide that RSA key exchange lacks?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
ECDHE provides perfect forward secrecy.
ECDHE (Elliptic Curve Diffie-Hellman Ephemeral) provides Perfect Forward Secrecy (PFS), meaning that if the server's long-term private key is compromised, past session keys cannot be derived. RSA key exchange does not provide PFS because the session key is encrypted with the server's static RSA public key; if the private key is later exposed, all recorded sessions can be decrypted.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
ECDHE provides perfect forward secrecy.
Why this is correct
This ensures that compromise of the server's long-term key does not expose past session keys.
Related concept
Read the scenario before looking for a memorised answer.
✗
ECDHE is faster than RSA key exchange.
Why it's wrong here
Performance is not the primary security reason; ECDHE may be faster but that's not the key property.
✗
ECDHE is required by PCI DSS for all web transactions.
Why it's wrong here
PCI DSS does not mandate a specific key exchange algorithm.
✗
ECDHE uses smaller key sizes for equivalent security.
Why it's wrong here
While true, this is not the primary security improvement over RSA.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse the general benefits of elliptic curve cryptography (smaller keys, speed) with the specific security property of Perfect Forward Secrecy, which is the unique advantage of ephemeral Diffie-Hellman over static RSA key exchange.
Detailed technical explanation
How to think about this question
In RSA key exchange, the client generates a pre-master secret, encrypts it with the server's RSA public key, and sends it; the server decrypts it with its private key. If an attacker records this traffic and later obtains the private key, they can decrypt the pre-master secret and derive the session keys. With ECDHE, the server generates an ephemeral Diffie-Hellman key pair for each session, signs it with its long-term key, and the client and server perform a key agreement that produces a unique session key; even if the signing key is later compromised, the ephemeral keys are discarded and cannot be recovered, ensuring PFS.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Cryptography — This question tests Cryptography — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: ECDHE provides perfect forward secrecy. — ECDHE (Elliptic Curve Diffie-Hellman Ephemeral) provides Perfect Forward Secrecy (PFS), meaning that if the server's long-term private key is compromised, past session keys cannot be derived. RSA key exchange does not provide PFS because the session key is encrypted with the server's static RSA public key; if the private key is later exposed, all recorded sessions can be decrypted.
What should I do if I get this SSCP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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This SSCP 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 SSCP exam.
Question Discussion
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