Comment 12 for bug 1348339

I don't think we can upgrade the code in question from MD5 to SHA256 at the moment.

The Swift put_object() call's response has an etag field. This etag field is populated with the MD5 hash for the data segment received by Swift, and it is calculated by Swift.

I took a quick look at the Swift code, and don't see evidence of etag hash algorithm being configurable on Swift.

This posting is also saying etag is MD5 only:
https://answers.launchpad.net/swift/+question/217171

Since MD5 is a constraint imposed by Swift, unless Swift starts to support SHA etags, I don't believe we have other choice at the moment but to stick with MD5 here.