func (ssec) IsEncrypted(metadata map[string]string) bool {
	if _, ok := metadata[MetaSealedKeySSEC]; ok {
		return true
	}
	return false
}

// ParseHTTP parses the SSE-C headers and returns the SSE-C client key
// on success. SSE-C copy headers are ignored.
func (ssec) ParseHTTP(h http.Header) (key [32]byte, err error) {
	if h.Get(xhttp.AmzServerSideEncryptionCustomerAlgorithm) != xhttp.AmzEncryptionAES {