XK0-006 Security Practice Question
A Linux security administrator needs to generate a self-signed certificate for a web server. They want to create a private key and a certificate signing request (CSR) in one step. Which OpenSSL command should be used?
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
✓
openssl req -new -newkey rsa:2048 -nodes -keyout key.pem -out req.pem
The 'req -new -newkey rsa:2048 -nodes -keyout key.pem -out req.pem' command generates a new private key and CSR. The other options either generate a self-signed certificate directly or are incomplete.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
openssl genrsa -out key.pem 2048 && openssl req -new -key key.pem -out req.pem
Why it's wrong here
This also works but is two commands, not one step. The question asks for one step.
- ✗
openssl req -new -key key.pem -out req.pem
Why it's wrong here
This assumes the private key already exists, does not create one.
- ✗
openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365
Why it's wrong here
This creates a self-signed certificate, not a CSR.
- ✓
openssl req -new -newkey rsa:2048 -nodes -keyout key.pem -out req.pem
Why this is correct
This creates a new private key and CSR.
Quick reference
Asymmetric Encryption Algorithm Comparison
| Algorithm | Key Exchange | Signatures | Equivalent Security Key | Notes |
|---|---|---|---|---|
| RSA-3072 | Yes | Yes | 128-bit | Widely deployed; slow for bulk data |
| ECDSA P-256 | No | Yes | 128-bit | Fast signatures; standard TLS certs |
| ECDH / ECDHE | Yes | No | 128-bit | Perfect forward secrecy in TLS 1.3 |
| DH / DHE | Yes | No | 128-bit (3072-bit key) | Replaced by ECDHE in modern TLS |
| Ed25519 | No | Yes | ~128-bit | SSH keys, modern PKI |
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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