Secrets encryption at rest in Kubernetes - Step-by-Step Execution

Process Flow - Secrets encryption at rest

Create Secret in Kubernetes

↓

Secret stored in etcd (unencrypted)

↓

Enable Encryption Configuration

↓

Kubernetes API Server encrypts Secret data

↓

Encrypted Secret stored in etcd

↓

When Secret requested

↓

API Server decrypts Secret before returning

↓

User gets decrypted Secret

This flow shows how Kubernetes encrypts Secrets before saving them in etcd and decrypts them when accessed.

Execution Sample

Kubernetes

apiVersion: apiserver.config.k8s.io/v1
kind: EncryptionConfiguration
resources:
  - resources:
    - secrets
    providers:
    - aescbc:
        keys:
        - name: key1
          secret: <base64-encoded-key>
    - identity: {}

This config enables AES-CBC encryption for Secrets stored in etcd.

Process Table

Step	Action	Secret State in etcd	API Server Behavior	Result
1	Create Secret 'mysecret'	Plaintext stored	No encryption configured	Secret saved unencrypted
2	Apply EncryptionConfiguration	New secrets encrypted; existing unencrypted	API Server encrypts Secrets before saving	New secrets stored encrypted
3	Request Secret 'mysecret'	Encrypted data in etcd	API Server decrypts Secret before returning	User receives plaintext Secret
4	Update Secret 'mysecret'	Encrypted data updated	API Server encrypts updated Secret	Updated Secret stored encrypted
5	Delete EncryptionConfiguration	Secrets remain encrypted	API Server stops encrypting new Secrets	New Secrets stored unencrypted
6	Request Secret 'mysecret'	Encrypted data in etcd	API Server decrypts Secret	User receives decrypted Secret
7	Exit	N/A	N/A	Process ends

💡 Process ends after Secret retrieval and encryption configuration changes

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	After Step 6	Final
Secret Data in etcd	None	Plaintext	Encrypted	Encrypted	Encrypted	Encrypted	Encrypted	Encrypted
API Server Encryption Enabled	False	False	True	True	True	False	False	False
User Receives	None	Plaintext Secret	Plaintext Secret	Plaintext Secret	Plaintext Secret	Plaintext Secret	Plaintext Secret	Plaintext Secret

Key Moments - 3 Insights

Why is the Secret stored unencrypted at first (Step 1) but new Secrets encrypted after applying EncryptionConfiguration (Step 2)?

Initially, Kubernetes stores Secrets as plaintext in etcd because encryption is not enabled. After applying EncryptionConfiguration, the API Server encrypts new Secrets before saving them, so etcd stores encrypted data (see execution_table rows 1 and 2).

If the EncryptionConfiguration is deleted (Step 5), are existing Secrets decrypted in etcd?

No, existing Secrets remain encrypted in etcd. Deleting the config stops encrypting new Secrets, but stored Secrets stay encrypted until manually decrypted or rotated (see execution_table row 5).

When a Secret is requested, why does the user always get the decrypted Secret even though etcd stores encrypted data?

The API Server decrypts Secrets on retrieval before returning them to the user, so users always see plaintext Secrets regardless of encryption at rest (see execution_table rows 3 and 6).

Visual Quiz - 3 Questions

Look at the execution_table at Step 2. What changes in the API Server behavior?

A It stops encrypting Secrets

B It deletes Secrets from etcd

C It starts encrypting Secrets before saving to etcd

D It returns Secrets unencrypted to users

💡 Hint

Check the 'API Server Behavior' column at Step 2 in the execution_table

At which step does the user receive the Secret for the first time?

A Step 3

B Step 1

C Step 5

D Step 7

💡 Hint

Look at the 'User Receives' column in variable_tracker after Step 1 and Step 3

If EncryptionConfiguration is removed, what happens to new Secrets stored after Step 5?

A They are stored unencrypted

B They are deleted automatically

C They are encrypted with the old key

D They cause an error on save

💡 Hint

See 'API Server Encryption Enabled' variable_tracker value after Step 5 and execution_table Step 5

Concept Snapshot

Kubernetes Secrets encryption at rest:
- Secrets stored in etcd by default are unencrypted.
- Enable encryption via EncryptionConfiguration in API Server.
- API Server encrypts Secrets before saving to etcd.
- Secrets are decrypted by API Server when accessed.
- Removing encryption config stops encrypting new Secrets but existing remain encrypted.
- Protects sensitive data stored in cluster backend.

Full Transcript

This visual execution shows how Kubernetes handles Secrets encryption at rest. Initially, Secrets are stored in plaintext in etcd. When an EncryptionConfiguration is applied, the API Server encrypts Secrets before saving them, so etcd stores encrypted data. When a Secret is requested, the API Server decrypts it before returning it to the user, ensuring users always see plaintext Secrets. If the encryption config is removed, new Secrets are stored unencrypted, but existing encrypted Secrets remain encrypted in etcd. This process protects sensitive data stored in the cluster backend.

Practice

1. What is the main purpose of enabling Secrets encryption at rest in Kubernetes?

easy

A. To protect sensitive data stored in etcd from unauthorized access

B. To speed up the retrieval of Secrets from the API server

C. To allow Secrets to be shared publicly across namespaces

D. To automatically rotate Secrets without manual intervention

Solution

1. Step 1: Understand what Secrets encryption at rest means

   It means encrypting sensitive data stored on disk, specifically in etcd, to prevent unauthorized access if someone gains access to the storage.

2. Step 2: Identify the main goal of this encryption

   The goal is to protect sensitive data like passwords or tokens stored in etcd, not to speed up access or share Secrets publicly.

3. Final Answer:

   To protect sensitive data stored in etcd from unauthorized access -> Option A

4. Quick Check:

   Secrets encryption = protect data at rest [OK]

Hint: Encryption at rest means protecting stored data, not speeding access [OK]

Common Mistakes:

• Confusing encryption at rest with encryption in transit
• Thinking encryption shares Secrets publicly
• Assuming encryption automatically rotates Secrets

2. Which of the following is the correct way to enable Secrets encryption at rest in Kubernetes EncryptionConfiguration file?

easy

A. apiVersion: apiserver.config.k8s.io/v1
kind: EncryptionConfiguration
resources:
- resources:
- secrets
providers:
- aescbc:
keys:
- name: key1
secret:
- identity: {}

B. apiVersion: v1
kind: Secret
metadata:
name: encryption-config
stringData:
key:

C. apiVersion: apiserver.config.k8s.io/v1
kind: EncryptionConfiguration
resources:
- secrets
providers:
- identity: {}
- aescbc:
keys:
- name: key1
secret:

D. apiVersion: apiserver.config.k8s.io/v1
kind: EncryptionConfig
resources:
- secrets
- aescbc:
keys:
- name: key1
secret:

Solution

1. Step 1: Review the correct structure of EncryptionConfiguration

   The file must have apiVersion, kind, and a resources list with nested resources and providers. The providers list includes encryption methods like aescbc and identity.

2. Step 2: Compare options for correct YAML syntax and structure

   apiVersion: apiserver.config.k8s.io/v1 kind: EncryptionConfiguration resources: - secrets providers: - identity: {} - aescbc: keys: - name: key1 secret: correctly nests resources and providers, uses aescbc with keys, and includes identity as fallback. apiVersion: apiserver.config.k8s.io/v1 kind: EncryptionConfiguration resources: - resources: - secrets providers: - aescbc: keys: - name: key1 secret: - identity: {} incorrectly nests 'resources' under 'resources'. Others have syntax errors or wrong kind names.

3. Final Answer:

   apiVersion: apiserver.config.k8s.io/v1 kind: EncryptionConfiguration resources: - secrets providers: - identity: {} - aescbc: keys: - name: key1 secret: -> Option C

4. Quick Check:

   Correct YAML structure = apiVersion: apiserver.config.k8s.io/v1 kind: EncryptionConfiguration resources: - secrets providers: - identity: {} - aescbc: keys: - name: key1 secret: [OK]

Hint: Look for 'resources' as a list of resource names and 'providers' as a list of encryption methods [OK]

Common Mistakes:

• Using wrong kind name like EncryptionConfig instead of EncryptionConfiguration
• Incorrect YAML indentation or missing nested keys
• Placing keys outside the providers list
• Nesting 'resources' under 'resources' incorrectly

3. Given this snippet from a Kubernetes API server log after enabling Secrets encryption at rest:

"Encryption provider aescbc is enabled for resource secrets"
"Using key named key1 for encryption"
"Secrets stored in etcd are now encrypted"

What is the expected effect when retrieving a Secret via kubectl get secret?

medium

A. The Secret data is shown as base64-encoded encrypted strings

B. The Secret data is automatically decrypted and shown in base64-encoded plain text

C. The Secret cannot be retrieved until manual decryption is done

D. The Secret is deleted from etcd after retrieval

Solution

1. Step 1: Understand encryption at rest vs API response

   Encryption at rest means data is encrypted in storage (etcd), but the API server decrypts it before sending to clients.

2. Step 2: Determine what kubectl get secret shows

   kubectl shows the decrypted Secret data in base64-encoded form, which is normal for Secrets, not encrypted ciphertext.

3. Final Answer:

   The Secret data is automatically decrypted and shown in base64-encoded plain text -> Option B

4. Quick Check:

   Encryption at rest decrypts before API response [OK]

Hint: Encryption at rest is transparent to kubectl output [OK]

Common Mistakes:

• Thinking Secrets remain encrypted when retrieved
• Confusing base64 encoding with encryption
• Assuming manual decryption is needed

4. You configured Secrets encryption at rest but notice that Secrets are still stored unencrypted in etcd. What is the most likely cause?

medium

A. The Secrets were created before enabling encryption and never updated

B. The encryption key is too short and rejected silently

C. The etcd cluster does not support encryption

D. The API server was not restarted after applying the encryption config

Solution

1. Step 1: Recall how encryption config is applied

   The API server must be restarted to load the new encryption configuration and apply encryption to new Secrets.

2. Step 2: Identify why Secrets remain unencrypted

   If the API server is not restarted, it continues to store Secrets unencrypted despite config changes.

3. Final Answer:

   The API server was not restarted after applying the encryption config -> Option D

4. Quick Check:

   Restart API server to apply encryption config [OK]

Hint: Always restart API server after changing encryption config [OK]

Common Mistakes:

• Assuming existing Secrets auto-encrypt without update
• Believing etcd cannot support encryption
• Ignoring the need to restart API server

5. You want to rotate the encryption key used for Secrets encryption at rest without downtime. Which approach correctly achieves this?

hard

A. Add the new key as the first provider in the encryption config, keep the old key second, then restart the API server

B. Replace the old key with the new key in the config and restart the API server immediately

C. Delete all Secrets, update the key, then recreate Secrets encrypted with the new key

D. Update the key in etcd directly without changing the API server config

Solution

1. Step 1: Understand key rotation in encryption config

   To rotate keys safely, add the new key first so new Secrets encrypt with it, and keep the old key to decrypt existing Secrets.

2. Step 2: Apply config and restart API server

   Restarting the API server loads the new config. Existing Secrets remain decryptable with the old key, allowing smooth rotation.

3. Final Answer:

   Add the new key as the first provider in the encryption config, keep the old key second, then restart the API server -> Option A

4. Quick Check:

   New key first, old key second, restart API server [OK]

Hint: New key first, old key second in config for smooth rotation [OK]

Common Mistakes:

• Replacing old key immediately causing decryption failures
• Deleting Secrets instead of rotating keys
• Modifying etcd data directly risking corruption