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Encryption-At-Rest

Tutorial: Setting up and using Encryption-At-Rest in KurrentDB

The Encryption-At-Rest feature provides encryption for KurrentDB to secure database chunk files, ensuring data protection even if an attacker gains access to the physical disk. This step-by-step guide will walk you through the process of enabling and configuring this feature, including generating master keys and applying encryption.

Prerequisites:

Step 1: Verify license key

Ensure you have a valid license key to use the Encryption-At-Rest feature. Without this license, the feature will not be functional.

Step 2 (optional): Confirm Encryption-At-Rest availability

By default, Encryption-At-Rest is bundled with KurrentDB 25.0 or later, or EventStoreDB 24.10 LTS. You can confirm its availability in the KurrentDB logs. Look for the following log message:

[INF] ClusterVNodeHostedService Loaded SubsystemsPlugin plugin: encryption-at-rest 24.10.0.1316

Refer to the log documentation for instructions on accessing KurrentDB logs.

Step 3: Generate a master key

To encrypt the data, you must first generate a master key using the es-cli tool (available to be downloaded in Cloudsmith). This key is used to derive the data keys that will encrypt chunk files.

Run the following command to generate a master key:

es-cli encryption generate-master-key

Place the generated master key in a secure directory on a separate drive from the database files, ensuring enhanced security. The key should be stored in the directory you will configure in the next step, for example, /secure/keys/.

Step 4: Configure and enable Encryption-At-Rest

Step 4.1: Add the configuration file

  1. Navigate to the config directory within the KurrentDB installation.
    There are multiple configuration mechanisms available. Since options set in a JSON configuration override those set in a YAML configuration, here is an example using JSON. You can also find a YAML configuration file example in the documentation.

    Create a new JSON configuration file (e.g., encryption-config.json) with the following content:

    {
  "EventStore": {  
    "Plugins": {  
      "EncryptionAtRest": {  
        "Enabled": true,  
        "MasterKey": { 
          "File": {  
            "KeyPath": "/secure/keys/"  // Update with the actual path to your keys  
          }  
        },  
        "Encryption": {  
          "AesGcm": {  
            "Enabled": true,  
            "KeySize": 256  // Optional: 128, 192, 256 bits (default is 256)  
          }  
        }  
      }  
    } 
  }  
}

  2. Make sure to replace /secure/keys/ with the actual path where the generated master key is stored.

Step 4.2: Set the encryption algorithm

In the main KurrentDB configuration file, add the following line to specify the encryption transformation:

Transform: aes-gcm

This ensures that the AES Galois Counter Mode (AES-GCM) encryption algorithm is applied to new chunks.

Step 5: Confirm Encryption-At-Rest activation

After configuring Encryption-At-Rest, you can confirm it is enabled and active by checking the log file. You should see the following log messages:

...
[141828, 1,11:42:45.325,INF] Encryption-At-Rest: Loaded master key source: "File"
[141828, 1,11:42:45.340,INF] Encryption-At-Rest: (File) Loaded master key: 1 (256 bits)
[141828, 1,11:42:45.345,INF] Encryption-At-Rest: Active master key ID: 1
[141828, 1,11:42:45.345,INF] Encryption-At-Rest: Loaded encryption algorithm: "AesGcm"
[141828, 1,11:42:45.347,INF] Encryption-At-Rest: (AesGcm) Using key size: 256 bits
[141828, 1,11:42:45.401,INF] Loaded the following transforms: Identity, Encryption_AesGcm
[141828, 1,11:42:45.402,INF] Active transform set to: Encryption_AesGcm
...

Step 6 (optional): Verify encryption

Once Encryption-At-Rest is enabled, new chunk files created or scavenged will be encrypted using the configured encryption algorithm. You can verify encryption with the following tests:

  • New chunks test:
    • Create or scavenge chunk files and verify by checking the logs to confirm that new chunks have been encrypted.
    • Example log message that indicates the active encryption mechanism is operational:
      [141828, 1,11:42:45.401,INF] Active transform set to: Encryption_AesGcm
  • Unauthorized access test:
    • Attempt to access encrypted files without proper keys to confirm they cannot be read.
    • For example, you can attempt to read encrypted chunk files directly using a text editor, hexadecimal viewer, or unsupported tool. Without the proper master key, the contents should appear garbled or unreadable.

Step 7: Important considerations

  • Irreversible encryption: Once encryption is enabled, you cannot revert to an unencrypted state if any new chunk file has been created or scavenged. To decrypt the encrypted chunks, special tooling would be required (currently unavailable).
  • Master key management:
    • If your master key is compromised, the entire database can be decrypted. Always secure the key on a different drive than your database files.
    • If your master key is lost or corrupted, you’ll lose access to your data. Always keep a backup of your master key in a safe place.
  • Scope of protection: Encryption-At-Rest encrypts chunk files but does not encrypt index files. Additionally, this feature does not protect against memory-dump-based attacks, which require separate mitigation strategies.

Summary

By following this tutorial, you have successfully configured and enabled Encryption-At-Rest in KurrentDB. This encryption setup ensures that your chunk files are securely encrypted, protecting your data from potential disk-based attacks.

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