What Makes Data Unreadable Without a Key?

DA0-002 By islever Editorial Last updated Oct 23, 2026

Compare privacy and protection strategies

Short answer

C Encryption converts readable plaintext into ciphertext that can only be restored to its original form with the required decryption key.

Question

Which of the following makes data unreadable without a required key?

Anonymization
Role-based access control
Encryption Correct Answer
Masking

Key Takeaways

The question tests whether you can tell data protection by transformation (encryption) apart from de-identification or access restriction, with the common trap being to pick masking or anonymization because they also 'hide' data.

This DA0-002 practice question asks which technique renders data unreadable unless a required key is supplied, distinguishing encryption from anonymization, masking, and role-based access control. The page establishes that encryption is the only option that mathematically transforms readable plaintext into ciphertext that cannot be reversed without the decryption key.

Common mistake: Test-takers often choose D (Masking) because masking hides data values, but masking replaces or obscures fields for display and does not require a cryptographic key to reverse the transformation.

Expert Analysis

Why the Answer Is Correct

Encryption converts plaintext into ciphertext using an algorithm and a key, so without the matching key the data is mathematically unreadable — exactly matching the question's wording about a "required key." As jhon456 explained, "A required key is needed to decrypt the data and return it to its original readable form." This is the defining property of encryption and separates it from every other option listed.

Why the Other Options Are Wrong

Anonymization (A) removes or alters identifying information so a person cannot be re-identified; it is not reversed with a key and is generally irreversible. Role-based access control (B) governs who may view data at all — it never makes the stored data itself unreadable, so an authorized user still sees clear values. Masking (D) substitutes or obscures values for display or non-production use, but it does not rely on a decryption key to restore the original data.

Community Comment Notes

Both rf18 and jhon456 selected C, with jhon456 providing a full breakdown: "Encryption converts readable data (plaintext) into an unreadable form (ciphertext) using an encryption algorithm." rf18 also flagged that "this exam not updated since september 3," which is a reminder to confirm objectives against the current DA0-002 blueprint rather than relying on stale answer keys.

Official Reference

https://csrc.nist.gov/glossary/term/encryption

This link opens the official vendor documentation in a new tab.

Exam Strategy

Anchor on the phrase "required key" — only cryptographic encryption is defined by key-based reversibility. Eliminate options that describe de-identification (anonymization, masking) or permission control (RBAC) before answering.

Frequently Asked Questions

Why is masking not the same as encryption for this question?

Masking hides or substitutes values for display and does not require a cryptographic key to reverse it, so it fails the question's "required key" criterion.

Does role-based access control make stored data unreadable?

No. RBAC only controls who is permitted to access data; the data itself remains in readable form for anyone with the proper role.

More DA0-002 FAQ →

Discussion 3 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 3

jhon456 👍 1 Answered C

Encryption converts readable data (plaintext) into an unreadable form (ciphertext) using an encryption algorithm. A required key is needed to decrypt the data and return it to its original readable form. A. Anonymization — Removes or alters identifying information so a person cannot easily be identified. B. Role-based access control (RBAC) — Controls who is allowed to access data based on their role; it does not make the data itself unreadable. C. Encryption ✅ — Makes data unreadable without the correct key. D. Masking — Hides parts of data, such as displaying **1234, but does not necessarily require a key to reveal the original data. Answer: C. Encryption
TreyPar3 👍 1 Answered C

Just took this test, answer are not up to date, neither is the question pool.
rf18 👍 1 Answered C

this exam not updated since september 3 , can we have someone check it

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