The correct approach is to use Cloud KMS to create an AEAD key and then apply BigQuery’s built-in `AEAD.ENCRYPT` and `AEAD.DECRYPT` SQL functions for column-level encryption. This is correct because AEAD (Authenticated Encryption with Associated Data) provides both confidentiality and integrity for sensitive data, and by storing the key in Cloud KMS as a customer-managed key, you retain full control over access and key rotation. On the Google Professional Cloud Security Engineer exam, this scenario tests your understanding of how to implement data protection at rest within BigQuery without relying on default Google-managed encryption. A common trap is confusing column-level encryption with table-level or CMEK; remember that AEAD functions operate on individual column values during query time, not on the entire table. For a memory tip, think “AEAD = Add Encryption At Data-level,” reinforcing that the encryption happens within the SQL query itself, not at the storage layer.
PCSE Ensuring data protection Practice Question
This PCSE practice question tests your understanding of ensuring data protection. 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.
A multinational corporation is required to protect sensitive data in BigQuery using column-level encryption. They want to use a customer-managed key stored in Cloud KMS. What is the correct approach?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use Cloud KMS to create an AEAD key and use BigQuery SQL functions to encrypt/decrypt.
Option C is correct because BigQuery supports column-level encryption and decryption using AEAD (Authenticated Encryption with Associated Data) keys created in Cloud KMS. The `AEAD.ENCRYPT` and `AEAD.DECRYPT` SQL functions allow you to encrypt specific columns at rest, using a customer-managed key that you control in Cloud KMS, ensuring that only authorized users with access to the key can decrypt the data.
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.
✗
Use Cloud DLP to de-identify columns in transit.
Why it's wrong here
DLP is for inspection and masking, not native BigQuery column encryption.
✗
Use Cloud HSM to store the key and apply bucket-level encryption.
Why it's wrong here
Cloud HSM is for key storage, not for BigQuery column encryption.
✓
Use Cloud KMS to create an AEAD key and use BigQuery SQL functions to encrypt/decrypt.
Why this is correct
BigQuery has AEAD.ENCRYPT/DECRYPT functions that integrate with Cloud KMS.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use Customer-Supplied Encryption Keys (CSEK) with BigQuery.
Why it's wrong here
CSEK is not supported in BigQuery.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the distinction between encryption services (Cloud KMS, Cloud HSM, CSEK) and their applicable scopes (bucket-level vs. column-level), so the trap here is assuming that any key management service can be used for BigQuery column-level encryption without understanding that only Cloud KMS with AEAD SQL functions is supported.
Detailed technical explanation
How to think about this question
AEAD encryption in BigQuery uses a key encryption key (KEK) stored in Cloud KMS and a data encryption key (DEK) that is wrapped by the KEK; the DEK is used to encrypt the column data, and the wrapped DEK is stored alongside the encrypted data. This approach ensures that the plaintext key never leaves Cloud KMS, and you can rotate the KEK independently of the DEK. In practice, this allows fine-grained access control where users with the `cloudkms.cryptoKeyVersions.useToDecrypt` permission can decrypt specific columns, while others see only ciphertext.
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.
Ensuring data protection — This question tests Ensuring data protection — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use Cloud KMS to create an AEAD key and use BigQuery SQL functions to encrypt/decrypt. — Option C is correct because BigQuery supports column-level encryption and decryption using AEAD (Authenticated Encryption with Associated Data) keys created in Cloud KMS. The `AEAD.ENCRYPT` and `AEAD.DECRYPT` SQL functions allow you to encrypt specific columns at rest, using a customer-managed key that you control in Cloud KMS, ensuring that only authorized users with access to the key can decrypt the data.
What should I do if I get this PCSE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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