checksumAlgorithm

Indicates the algorithm that you want Amazon S3 to use to create the checksum for the object. For more information, see Checking object integrity in the Amazon S3 User Guide.

When you copy an object, if the source object has a checksum, that checksum value will be copied to the new object by default. If the CopyObject request does not include this x-amz-checksum-algorithm header, the checksum algorithm will be copied from the source object to the destination object (if it's present on the source object). You can optionally specify a different checksum algorithm to use with the x-amz-checksum-algorithm header. Unrecognized or unsupported values will respond with the HTTP status code 400 Bad Request.

For directory buckets, when you use Amazon Web Services SDKs, CRC32 is the default checksum algorithm that's used for performance.