Comprehensive and Detailed in Depth Explanation:

The Transit secrets engine in Vault is designed for encryption-as-a-service, not data storage. Let’s evaluate:

Option A: 24 hours Transit doesn’t store ciphertext, so no TTL applies. Incorrect.

Option B: 30 days No storage means no 30-day retention. Incorrect.

Option C: 32 days This aligns with token TTLs, not Transit behavior. Incorrect.

Option D: Transit does not store data Transit encrypts data and returns the ciphertext to the caller without persisting it in Vault. Correct.

Detailed Mechanics:

When you run vault write transit/encrypt/mykey plaintext= < base64-data > , Vault uses the named key (e.g., mykey) to encrypt the input and returns a response like vault:v1: < ciphertext > . This ciphertext is not stored in Vault’s storage backend (e.g., Consul, Raft); it’s the client’s responsibility to save it (e.g., in a database). This stateless design keeps Vault lightweight and secure, avoiding data retention risks.

Real-World Example:

Encrypt a credit card: vault write transit/encrypt/creditcard plaintext=$(base64 < < < " 1234-5678-9012-3456 " ). Response: ciphertext=vault:v1: < data > . You store this in your app’s database; Vault retains nothing.

Overall Explanation from Vault Docs:

“Vault does NOT store any data encrypted via the transit/encrypt endpoint… The ciphertext is returned to the caller for storage elsewhere.”