AWS::S3::Bucket ServerSideEncryptionByDefault - AWS CloudFormation

AWS::S3::Bucket ServerSideEncryptionByDefault

Describes the default server-side encryption to apply to new objects in the bucket. If a PUT Object request doesn't specify any server-side encryption, this default encryption will be applied. If you don't specify a customer managed key at configuration, Amazon S3 automatically creates an AWS KMS key in your AWS account the first time that you add an object encrypted with SSE-KMS to a bucket. By default, Amazon S3 uses this KMS key for SSE-KMS. For more information, see PUT Bucket encryption in the Amazon S3 API Reference.


To declare this entity in your AWS CloudFormation template, use the following syntax:


{ "KMSMasterKeyID" : String, "SSEAlgorithm" : String }


KMSMasterKeyID: String SSEAlgorithm: String



KMS key ID to use for the default encryption. This parameter is allowed if SSEAlgorithm is aws:kms.

You can specify the key ID, key alias, or the Amazon Resource Name (ARN) of the CMK. However, if you are using encryption with cross-account operations, you must use a fully qualified CMK ARN. For more information, see Using encryption for cross-account operations.

For example:

  • Key ID: 1234abcd-12ab-34cd-56ef-1234567890ab

  • Key ARN: arn:aws:kms:us-east-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab


Amazon S3 only supports symmetric KMS keys and not asymmetric KMS keys. For more information, see Using Symmetric and Asymmetric Keys in the AWS Key Management Service Developer Guide.

Required: No

Type: String

Update requires: No interruption


Server-side encryption algorithm to use for the default encryption.

Required: Yes

Type: String

Allowed values: AES256 | aws:kms | aws:kms:dsse

Update requires: No interruption


Create a bucket with default encryption

The following example creates a bucket with server-side bucket encryption configured. This example uses encryption with AWS KMS keys (SSE-KMS). You can use dual-layer server-side encryption with AWS KMS keys (DSSE-KMS) by specifying aws:kms:dsse for SSEAlgorithm. You can also use server-side encryption with S3-managed keys (SSE-S3) by modifying the Amazon S3 Bucket ServerSideEncryptionByDefault property to specify AES256 for SSEAlgorithm. For more information, see Using SSE-S3 in the Amazon S3 User Guide.


{ "AWSTemplateFormatVersion": "2010-09-09", "Description": "S3 bucket with default encryption", "Resources": { "EncryptedS3Bucket": { "Type": "AWS::S3::Bucket", "Properties": { "BucketName": { "Fn::Sub": "encryptedbucket-${AWS::Region}-${AWS::AccountId}" }, "BucketEncryption": { "ServerSideEncryptionConfiguration": [ { "ServerSideEncryptionByDefault": { "SSEAlgorithm": "aws:kms", "KMSMasterKeyID": "KMS-KEY-ARN" } } ] } }, "DeletionPolicy": "Delete" } } }


AWSTemplateFormatVersion: 2010-09-09 Description: S3 bucket with default encryption Resources: EncryptedS3Bucket: Type: 'AWS::S3::Bucket' Properties: BucketName: !Sub 'encryptedbucket-${AWS::Region}-${AWS::AccountId}' BucketEncryption: ServerSideEncryptionConfiguration: - ServerSideEncryptionByDefault: SSEAlgorithm: 'aws:kms' KMSMasterKeyID: KMS-KEY-ARN DeletionPolicy: Delete