func UTCNow() time.Time {
	return time.Now().UTC()
}

// GenETag - generate UUID based ETag
func GenETag() string {
	return ToS3ETag(getMD5Hash([]byte(mustGetUUID())))
}

// ToS3ETag - return checksum to ETag
func ToS3ETag(etag string) string {
	etag = canonicalizeETag(etag)

	if !strings.HasSuffix(etag, "-1") {
		// Tools like s3cmd uses ETag as checksum of data to validate.

Esse "esperar por algo" normalmente se refere a operações <abbr title="Entrada e Saída">I/O</abbr> que são relativamente "lentas" (comparadas a velocidade do processador e da memória RAM), como esperar por:

* dados do cliente para serem enviados através da rede
* dados enviados pelo seu programa para serem recebidos pelo clente através da rede

Esa "espera de otra cosa" normalmente se refiere a operaciones <abbr title = "Input and Output, en español: Entrada y Salida.">I/O</abbr> que son relativamente "lentas" (en relación a la velocidad del procesador y memoria RAM), como por ejemplo esperar por:

* los datos de cliente que se envían a través de la red

rep_obj2_etag=$(echo "${stat_out2_rep}" | jq '.etag')
rep_obj2_size=$(echo "${stat_out2_rep}" | jq '.size')
rep_obj2_md5=$(echo "${stat_out2_rep}" | jq '.metadata."X-Amz-Server-Side-Encryption-Customer-Key-Md5"')

# Check the etag and size of replicated SSEC objects
if [ "${rep_obj1_etag}" != "${src_obj1_etag}" ]; then

			if _, ok := crypto.IsEncrypted(batch[i].UserDefined); ok {
				ETag, err := etag.Parse(batch[i].ETag)
				if err != nil {
					return err
				}
				if SSES3SinglePartObjects[i] && ETag.IsEncrypted() {
					ETag, err = etag.Decrypt(keys[0][:], ETag)
					if err != nil {
						return err
					}
					keys = keys[1:]
				}
				batch[i].ETag = ETag.Format().String()
			}
		}
		objects = objects[N:]
	}

rep_obj3_etag=$(echo "${stat_out3_rep}" | jq '.etag')
rep_obj3_size=$(echo "${stat_out3_rep}" | jq '.size')
rep_obj3_md5=$(echo "${stat_out3_rep}" | jq '.metadata."X-Amz-Server-Side-Encryption-Customer-Key-Md5"')

# Check the etag and size of replicated SSEC objects
if [ "${rep_obj1_etag}" != "${src_obj1_etag}" ]; then

// generates CopyObjectResponse from etag and lastModified time.
func generateCopyObjectResponse(etag string, lastModified time.Time) CopyObjectResponse {
	return CopyObjectResponse{
		ETag:         "\"" + etag + "\"",
		LastModified: amztime.ISO8601Format(lastModified.UTC()),
	}
}

// generates CopyObjectPartResponse from etag and lastModified time.

		if !meta.IsValid() {
			continue
		}
		etagOnly := modTime.Equal(timeSentinel) && (etag != "" && etag == meta.Metadata["etag"])
		mtimeValid := meta.ModTime.Equal(modTime)
		if mtimeValid || etagOnly {
			fmt.Fprintf(h, "%v", meta.XLV1)
			if !etagOnly {
				// Verify dataDir is same only when mtime is valid and etag is not considered.
				fmt.Fprintf(h, "%v", meta.GetDataDir())
			}

			if kmsCtx, ok := objInfo.UserDefined[crypto.MetaContext]; ok {
				w.Header().Set(xhttp.AmzServerSideEncryptionKmsContext, kmsCtx)
			}
			if len(objInfo.ETag) >= 32 && strings.Count(objInfo.ETag, "-") != 1 {
				objInfo.ETag = objInfo.ETag[len(objInfo.ETag)-32:]
			}
		case crypto.SSEC:
			w.Header().Set(xhttp.AmzServerSideEncryptionCustomerAlgorithm, r.Header.Get(xhttp.AmzServerSideEncryptionCustomerAlgorithm))

	// Set last modified time.
	lastModified := objInfo.ModTime.UTC().Format(http.TimeFormat)
	w.Header().Set(xhttp.LastModified, lastModified)

	// Set Etag if available.
	if objInfo.ETag != "" {
		w.Header()[xhttp.ETag] = []string{"\"" + objInfo.ETag + "\""}
	}

	if objInfo.ContentType != "" {
		w.Header().Set(xhttp.ContentType, objInfo.ContentType)
	}

	if objInfo.ContentEncoding != "" {