Quick Answer
GnuPG is the correct tool for encrypting files with public-key cryptography on Linux systems. It implements the OpenPGP standard (RFC 4880), which uses asymmetric encryption where you generate a key pair—a public key to share and a private key to keep secret—allowing you to encrypt a file with the recipient’s public key so only their private key can decrypt it. On the CompTIA Linux+ XK0-005 exam, this question tests your understanding of standard Linux security utilities; a common trap is confusing GnuPG with symmetric tools like OpenSSL’s enc command or file-level encryptors such as eCryptfs. Remember that GnuPG is specifically for asymmetric, public-key operations, while OpenSSL can do both but is not the default standard for this purpose. A simple memory tip: “GnuPG = GPG = Good Public Guard,” reinforcing that it guards data using public keys.
This XK0-005 practice question tests your understanding of security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which tool is used for encrypting files with public-key cryptography on Linux systems?
bcrypt
Why wrong: A password hashing algorithm, not for file encryption.
LUKS
Why wrong: Used for full disk encryption.
OpenSSL
Why wrong: Primarily used for SSL/TLS and certificate operations.
GnuPG
Implements the OpenPGP standard for encrypting and signing data.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
GnuPG
GnuPG (GNU Privacy Guard) is the correct tool because it implements the OpenPGP standard (RFC 4880) for encrypting and signing files using public-key cryptography. It allows users to generate a key pair, encrypt a file with the recipient's public key, and decrypt it with the corresponding private key, making it the standard Linux utility for asymmetric file encryption.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
bcrypt
Why it's wrong here
A password hashing algorithm, not for file encryption.
LUKS
Why it's wrong here
Used for full disk encryption.
OpenSSL
Why it's wrong here
Primarily used for SSL/TLS and certificate operations.
GnuPG
Why this is correct
Implements the OpenPGP standard for encrypting and signing data.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates confuse OpenSSL's ability to perform asymmetric operations (e.g., `openssl rsautl`) with it being the standard tool for public-key file encryption, while GnuPG is the dedicated utility for OpenPGP-compliant file encryption on Linux.
Detailed technical explanation
GnuPG uses a hybrid encryption scheme: it generates a random session key (symmetric) to encrypt the file with a cipher like AES-256, then encrypts that session key with the recipient's RSA or ECDSA public key. This ensures both speed and security. A common real-world scenario is encrypting sensitive configuration files before emailing them to a colleague, where only the recipient's private key can decrypt the session key and thus the file.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the XK0-005 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Security — This question tests Security — Read the scenario before looking for a memorised answer..
The correct answer is: GnuPG — GnuPG (GNU Privacy Guard) is the correct tool because it implements the OpenPGP standard (RFC 4880) for encrypting and signing files using public-key cryptography. It allows users to generate a key pair, encrypt a file with the recipient's public key, and decrypt it with the corresponding private key, making it the standard Linux utility for asymmetric file encryption.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
This XK0-005 practice question is part of Courseiva's free CompTIA 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 XK0-005 exam.
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