1.10 Ensure KMS Encryption Keys Are Rotated Within a Period of 90 Days

Information

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.

Impact:

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

Solution

From Google Cloud Console

Go to Cryptographic Keys by visiting: https://console.cloud.google.com/security/kms.

Click on the specific key ring

From the list of keys, choose the specific key and Click on Right side pop up the blade (3 dots).

Click on Edit rotation period.

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

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

Default Value:

By default, KMS encryption keys are rotated every 90 days.

See Also

https://workbench.cisecurity.org/benchmarks/9562

Item Details

Category: IDENTIFICATION AND AUTHENTICATION, SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|IA-5(1), 800-53|SC-28, 800-53|SC-28(1), CSCv7|14.8

Plugin: GCP

Control ID: 610845558a787122546e417c8bbc7a8e28c7a0f9bc321044ee924c4a29ceb3ef