AWS::S3::Bucket ServerSideEncryptionByDefault - AWS CloudFormation
SyntaxPropertiesExamples

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. For more information, see PutBucketEncryption.

Note

  • General purpose buckets - If you don't specify a customer managed key at configuration, Amazon S3 automatically creates an AWS KMS key (aws/s3) 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.

  • Directory buckets - Your SSE-KMS configuration can only support 1 customer managed key per directory bucket for the lifetime of the bucket. The AWS managed key (aws/s3) isn't supported.

  • Directory buckets - For directory buckets, there are only two supported options for server-side encryption: SSE-S3 and SSE-KMS.

Syntax

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

JSON

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

YAML

  KMSMasterKeyID: String
  SSEAlgorithm: String

Properties

KMSMasterKeyID

AWS Key Management Service (KMS) customer managed key ID to use for the default encryption.

Note

  • General purpose buckets - This parameter is allowed if and only if SSEAlgorithm is set to aws:kms or aws:kms:dsse.

  • Directory buckets - This parameter is allowed if and only if SSEAlgorithm is set to aws:kms.

You can specify the key ID, key alias, or the Amazon Resource Name (ARN) of the KMS key.

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

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

  • Key Alias: alias/alias-name

If you are using encryption with cross-account or AWS service operations, you must use a fully qualified KMS key ARN. For more information, see Using encryption for cross-account operations.

Note

  • General purpose buckets - If you're specifying a customer managed KMS key, we recommend using a fully qualified KMS key ARN. If you use a KMS key alias instead, then AWS KMS resolves the key within the requester’s account. This behavior can result in data that's encrypted with a KMS key that belongs to the requester, and not the bucket owner. Also, if you use a key ID, you can run into a LogDestination undeliverable error when creating a VPC flow log.

  • Directory buckets - When you specify an AWS KMS customer managed key for encryption in your directory bucket, only use the key ID or key ARN. The key alias format of the KMS key isn't supported.

Important

Amazon S3 only supports symmetric encryption KMS keys. For more information, see Asymmetric keys in AWS KMS in the AWS Key Management Service Developer Guide.

Required: No

Type: String

Update requires: No interruption

SSEAlgorithm

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

Note

For directory buckets, there are only two supported values for server-side encryption: AES256 and aws:kms.

Required: Yes

Type: String

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

Update requires: No interruption

Examples

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.

JSON

{
    "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"
        }
    }
}

YAML

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