200-201 Security Concepts Practice Question
A security analyst needs to verify the authenticity and integrity of a software update. The update is signed with a digital signature. Which key is used to verify the signature?
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
✓
Sender's public key
Digital signatures use asymmetric cryptography: the sender's private key signs, the public key verifies.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Sender's public key
Why this is correct
The sender's public key verifies the signature created by their private key.
- ✗
Sender's private key
Why it's wrong here
The sender's private key is used to sign, not verify.
- ✗
Recipient's public key
Why it's wrong here
The recipient's keys are not involved in verifying the sender's signature.
- ✗
Recipient's private key
Why it's wrong here
The recipient's private key is used for decryption, not signature verification.
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 200-201 practice question is part of Courseiva's free Cisco 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 200-201 exam.