Ensure KMS Encryption Keys Are Rotated Within a Period of 90 Days (2024)

Description:

Google Cloud Key Management Service stores cryptographic keys in a hierarchical structure designed for useful and elegant access control management.

The format for the rotation schedule depends on the client library that is used. For the gcloud command-line tool, the next rotation time must be in 'ISO' or 'RFC3339' format, and the rotation period must be in the form 'INTEGER[UNIT]', where units can be one of seconds (s), minutes (m), hours (h) or days (d).

Rationale:

Set a key rotation period and starting time. A key can be created with a specified 'rotation period', which is the time between when new key versions are generated automatically. A key can also be created with a specified next rotation time. A key is a named object representing a 'cryptographic key' used for a specific purpose. The key material, the actual bits used for 'encryption', can change over time as new key versions are created.

A key is used to protect some 'corpus of data'. A collection of files could be encrypted with the same key and people with 'decrypt' permissions on that key would be able to decrypt those files. Therefore, it's necessary to make sure the 'rotation period' is set to a specific time.

After a successful key rotation, the older key version is required in order to decrypt the data encrypted by that previous key version.

From Google Cloud Console

1. Go to 'Cryptographic Keys' by visiting: https://console.cloud.google.com/security/kms.
2. Click on the specific key ring
3. From the list of keys, choose the specific key and Click on 'Right side pop up the blade (3 dots)'.
4. Click on 'Edit rotation period'.
5. On the pop-up window, 'Select a new rotation period' in days which should be less than 90 and then choose 'Starting on' date (date from which the rotation period begins).

From Google Cloud CLI

1. Update and schedule rotation by 'ROTATION_PERIOD' and 'NEXT_ROTATION_TIME' for each key:

gcloud kms keys update new --keyring=KEY_RING --location=LOCATION --next-rotation-time=NEXT_ROTATION_TIME --rotation-period=ROTATION_PERIOD