How-To: Encrypt application state

Automatically encrypt state and manage key rotations

Introduction

Application state often needs to get encrypted at rest to provide stronger security in enterprise workloads or regulated environments. Dapr offers automatic client side encryption based on AES in Galois/Counter Mode (GCM), supporting keys of 128, 192, and 256-bits.

In addition to automatic encryption, Dapr supports primary and secondary encryption keys to make it easier for developers and ops teams to enable a key rotation strategy. This feature is supported by all Dapr state stores.

The encryption keys are always fetched from a secret, and cannot be supplied as plaintext values on the metadata section.

Enabling automatic encryption

  1. Add the following metadata section to any Dapr supported state store:
  1. metadata:
  2. - name: primaryEncryptionKey
  3.   secretKeyRef:
  4.     name: mysecret
  5.     key: mykey # key is optional.

For example, this is the full YAML of a Redis encrypted state store

  1. apiVersion: dapr.io/v1alpha1
  2. kind: Component
  3. metadata:
  4.   name: statestore
  5. spec:
  6.   type: state.redis
  7.   version: v1
  8.   metadata:
  9.   - name: redisHost
  10.     value: localhost:6379
  11.   - name: redisPassword
  12.     value: ""
  13.   - name: primaryEncryptionKey
  14.     secretKeyRef:
  15.       name: mysecret
  16.       key: mykey

You now have a Dapr state store that’s configured to fetch the encryption key from a secret named mysecret, containing the actual encryption key in a key named mykey.

The actual encryption key must be a valid, hex-encoded encryption key. We recommend using 128-bit encryption keys; 192-bit and 256-bit keys are supported too. Dapr errors and exists if the encryption key is invalid.

As an example, you can generate a random, hex-encoded 128-bit (16-byte) key with:

  1. openssl rand 16 | hexdump -v -e '/1 "%02x"'
  2. # Result will be similar to "cb321007ad11a9d23f963bff600d58e0"

Note that the secret store does not have to support keys

Key rotation

To support key rotation, Dapr provides a way to specify a secondary encryption key:

  1. metadata:
  2. - name: primaryEncryptionKey
  3.     secretKeyRef:
  4.       name: mysecret
  5.       key: mykey
  6. - name: secondaryEncryptionKey
  7.     secretKeyRef:
  8.       name: mysecret2
  9.       key: mykey2

When Dapr starts, it will fetch the secrets containing the encryption keys listed in the metadata section. Dapr knows which state item has been encrypted with which key automatically, as it appends the secretKeyRef.name field to the end of the actual state key.

To rotate a key, change the primaryEncryptionKey to point to a secret containing your new key, and move the old primary encryption key to the secondaryEncryptionKey. New data will be encrypted using the new key, and old data that’s retrieved will be decrypted using the secondary key. Any updates to data items encrypted using the old key will be re-encrypted using the new key. Note that when you rotate a key, data encrypted with the old key is not automatically re-encrypted unless your application writes it again. If you remove the rotated key (the now-secondary encryption key), you will not be able to access data that was encrypted with that.

Last modified June 23, 2022: Merge pull request #2550 from ItalyPaleAle/cosmosdb-harcoded-dapr-version (cf03237)