keyType

Indicates the type of customer master key (CMK) to use for encryption. The default setting is Amazon Web Services_OWNED_CMK. For more information about CMKs, see Customer Master Keys (CMKs). When you invoke CreateDeliveryStream or StartDeliveryStreamEncryption with KeyType set to CUSTOMER_MANAGED_CMK, Firehose invokes the Amazon KMS operation CreateGrant to create a grant that allows the Firehose service to use the customer managed CMK to perform encryption and decryption. Firehose manages that grant.

When you invoke StartDeliveryStreamEncryption to change the CMK for a Firehose stream that is encrypted with a customer managed CMK, Firehose schedules the grant it had on the old CMK for retirement.

You can use a CMK of type CUSTOMER_MANAGED_CMK to encrypt up to 500 Firehose streams. If a CreateDeliveryStream or StartDeliveryStreamEncryption operation exceeds this limit, Firehose throws a LimitExceededException.

To encrypt your Firehose stream, use symmetric CMKs. Firehose doesn't support asymmetric CMKs. For information about symmetric and asymmetric CMKs, see About Symmetric and Asymmetric CMKs in the Amazon Web Services Key Management Service developer guide.