Question 225 of 1,040
Design Secure ArchitecturesmediumMultiple ChoiceObjective-mapped

Quick Answer

The answer is that the key policy in account 3000 must be updated to explicitly grant the role in account 4000 permission to decrypt. This is because KMS key policies are resource-based policies that act as the sole gatekeeper for cross-account access; even if the role in account 4000 has an identity-based policy allowing kms:Decrypt, the KMS service requires an explicit authorization path from the key owner’s policy to allow a principal from a different account. On the SAA-C03 exam, this scenario tests your understanding that cross-account KMS decrypt requires a two-way authorization: the identity policy in the consuming account and the key policy in the owning account. A common trap is assuming an identity policy alone suffices, but KMS enforces the key policy first. Remember the mnemonic: “Key policy is the key to cross-account decrypt.”

SAA-C03 Design Secure Architectures Practice Question

This SAA-C03 practice question tests your understanding of design secure architectures. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.

Account 3000 owns a customer-managed KMS key (key-K). A data processing team in account 4000 needs to decrypt data encrypted with key-K. The role in account 4000 already has an identity policy allowing kms:Decrypt on key-K. Despite this, decrypt requests fail with an AccessDenied error referencing KMS. What is the most likely missing authorization step?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

  • Clue: "most likely"

    Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

Question 1mediummultiple choice
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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

Update key-K’s key policy in account 3000 to allow kms:Decrypt for the specific role principal in account 4000.

The correct answer is A because KMS key policies are resource-based policies that must explicitly grant cross-account access. Even though the role in account 4000 has an identity-based policy allowing kms:Decrypt, the key policy in account 3000 (the key owner) must also include a statement that permits the specific role principal from account 4000 to perform kms:Decrypt on key-K. Without this, the KMS service will deny the request due to the lack of a valid authorization path.

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.

  • Update key-K’s key policy in account 3000 to allow kms:Decrypt for the specific role principal in account 4000.

    Why this is correct

    For customer-managed KMS keys, key policy is a required authorization layer. Even with an IAM identity policy granting kms:Decrypt, KMS will deny the request unless the key policy also authorizes the calling principal to use the key for Decrypt.

    Clue confirmation

    The clue word "most likely" in the question point toward this answer.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Update the S3 bucket policy to allow kms:Decrypt for account 4000 principals on key-K.

    Why it's wrong here

    S3 bucket policies authorize S3 operations. They do not authorize KMS cryptographic usage decisions. KMS AccessDenied errors require a KMS key policy change (or other KMS authorization mechanism), not an S3 policy change.

  • Enable AWS managed key rotation on key-K and remove the existing key policy.

    Why it's wrong here

    Key rotation affects key material rotation schedule, not who can use the key. Removing key policy would eliminate the authorization configuration needed for KMS operations and would not solve the AccessDenied issue.

  • Switch the access from a role to an IAM user because KMS only supports user principals.

    Why it's wrong here

    KMS supports multiple principal types, including IAM roles and users, and federated principals. The failure is consistent with missing key policy authorization rather than a limitation on principal type.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates assume identity-based policies alone are sufficient for cross-account KMS operations, forgetting that KMS requires an explicit resource-based policy (key policy) grant for the external principal.

Detailed technical explanation

How to think about this question

Under the hood, KMS uses a two-step authorization model for cross-account access: the key policy must grant the external account (or its principal) the required action, and the external principal must have an identity-based policy allowing the same action. The key policy acts as a resource-based policy that overrides any identity-based permissions from the external account if not explicitly included. In real-world scenarios, this often catches teams who assume that identity policies alone suffice for cross-account KMS operations, leading to AccessDenied errors even when the IAM role appears correctly configured.

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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.

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.

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FAQ

Questions learners often ask

What does this SAA-C03 question test?

Design Secure Architectures — This question tests Design Secure Architectures — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Update key-K’s key policy in account 3000 to allow kms:Decrypt for the specific role principal in account 4000. — The correct answer is A because KMS key policies are resource-based policies that must explicitly grant cross-account access. Even though the role in account 4000 has an identity-based policy allowing kms:Decrypt, the key policy in account 3000 (the key owner) must also include a statement that permits the specific role principal from account 4000 to perform kms:Decrypt on key-K. Without this, the KMS service will deny the request due to the lack of a valid authorization path.

What should I do if I get this SAA-C03 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jun 11, 2026

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This SAA-C03 practice question is part of Courseiva's free Amazon Web Services 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 SAA-C03 exam.