Ensure GCP KMS encryption key is rotating every 90 days

Error: GCP KMS encryption key is not rotating every 90 days

Bridgecrew Policy ID: BC_GCP_GENERAL_4
Checkov Check ID: CKV_GCP_43
Severity: CRITICAL

GCP KMS encryption key is not rotating every 90 days

Description

Google Cloud Key Management Service stores cryptographic keys in a hierarchical structure designed for access control management. The format for the rotation schedule depends on the client library used. In Terraform, the rotation period unit must be seconds.

A key is a named object representing a cryptographic key used for a specific purpose, including data protection. The key material, the actual bits used for encryption, can change over time as new key versions are created. 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.

We recommend you set a key rotation period, including start time. A key can be created with a specified rotation period, which is the time when new key versions are generated automatically. A key can also be created with a specified next rotation time.

Fix - Runtime

GCP Console

To change the policy using the GCP Console, follow these steps:

  1. Log in to the GCP Console at https://console.cloud.google.com.
  2. Navigate to Cryptographic Keys.
  3. Select the specific key ring.
  4. From the list of keys, select the specific key and Click on the blade (3 dots) on the right side of the pop up.
  5. Click Edit rotation period.
  6. On the pop-up window, Select a new rotation period in days; this should be less than 90 days. Then select a Starting on date; this is when the rotation period begins.

CLI Command

Update and schedule rotation by ROTATION_PERIOD and NEXT_ROTATION_TIME for each key:

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

Fix - Buildtime

Terraform

  • Resource: google_kms_crypto_key
  • Argument: rotation_period
resource "google_kms_crypto_key" "key" {
  name            = "crypto-key-example"
  key_ring        = google_kms_key_ring.keyring.id
+ rotation_period = "7776000s"
}

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