Security in Amazon S3 - Amazon Simple Storage Service

Security in Amazon S3

Important

As announced on November 19, 2025, Amazon Simple Storage Service is deploying a new default bucket security setting that automatically disables server-side encryption with customer-provided keys (SSE-C) for all new general purpose buckets. For existing buckets in AWS accounts with no SSE-C encrypted objects, Amazon S3 will also disable SSE-C for all new write requests. For AWS accounts with SSE-C usage, Amazon S3 will not change the bucket encryption configuration on any of the existing buckets in those accounts. This deployment started on April 6, 2026, and will complete over the next few weeks in 37 AWS Regions, including the AWS China and AWS GovCloud (US) Regions.

With these changes, applications that need SSE-C encryption must deliberately enable SSE-C by using the PutBucketEncryption API operation after creating a new bucket. For more information about this change, see Default SSE-C setting for new buckets FAQ.

Cloud security at AWS is the highest priority. As an AWS customer, you benefit from a data center and network architecture that are built to meet the requirements of the most security-sensitive organizations.

Security is a shared responsibility between AWS and you. The shared responsibility model describes this as security of the cloud and security in the cloud:

Security of the cloud

AWS is responsible for protecting the infrastructure that runs AWS services in the AWS Cloud. AWS also provides you with services that you can use securely. The effectiveness of our security is regularly tested and verified by third-party auditors as part of the AWS compliance programs. To learn about the compliance programs that apply to Amazon S3, see AWS Services in Scope by Compliance Program.

Security in the cloud

Your responsibility is determined by the AWS service that you use. You are also responsible for other factors including the sensitivity of your data, your organization’s requirements, and applicable laws and regulations. For Amazon S3, your responsibility includes the following areas:

This documentation will help you understand how to apply the shared responsibility model when using Amazon S3. The following topics show you how to configure Amazon S3 to meet your security and compliance objectives. You'll also learn how to use other AWS services that can help you monitor and secure your Amazon S3 resources.

Note

For more information about using the Amazon S3 Express One Zone storage class with directory buckets, see S3 Express One Zone and Working with directory buckets.

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