Does this library support Aws4 Signatures?

[Aedalus]

I'm trying to upload a file through cloudfront, specifying x-amz-server-side-encryption-aws-kms-key-id and x-amz-server-side-encryption: aws:kms. I can confirm that this works when the encryption is set to AES256, but setting the header to aws:kms results in the following error:

Requests specifying Server Side Encryption with AWS KMS managed keys require AWS Signature Version 4.