Add checksum to existing objects that do not have a checksum

Hello,

I understand that you would like to know how to apply checksum for existing objects. To apply any of these checksum values to objects that are already uploaded to Amazon S3, you can copy the object. When you copy an object, you can specify whether you want to use the existing checksum algorithm or use a new one. You can specify a checksum algorithm when using any supported mechanism for copying objects, including S3 Batch Operations.

For more information about S3 Batch Operations, see Performing large-scale batch operations on Amazon S3 objects