func NewChecksumFromData(t ChecksumType, data []byte) *Checksum {
	if !t.IsSet() {
		return nil
	}
	h := t.Hasher()
	h.Write(data)
	raw := h.Sum(nil)
	c := Checksum{Type: t, Encoded: base64.StdEncoding.EncodeToString(raw), Raw: raw}
	if !c.Valid() {
		return nil
	}
	return &c
}

// ReadCheckSums will read checksums from b and return them.
func ReadCheckSums(b []byte, part int) map[string]string {

		writeSTSErrorResponse(ctx, w, ErrSTSInvalidParameterValue, err)
		return
	}

	if len(sessionPolicyStr) > 0 {
		claims[policy.SessionPolicyName] = base64.StdEncoding.EncodeToString([]byte(sessionPolicyStr))
	}

	secret, err := getTokenSigningKey()
	if err != nil {
		writeSTSErrorResponse(ctx, w, ErrSTSInternalError, err)
		return
	}

	stringToSign := signV4Algorithm + "\n" + t.Format(iso8601Format) + "\n"
	stringToSign += scope + "\n"
	canonicalRequestBytes := sha256.Sum256([]byte(canonicalRequest))
	stringToSign += hex.EncodeToString(canonicalRequestBytes[:])
	return stringToSign
}

// getSigningKey hmac seed to calculate final signature.
func getSigningKey(secretKey string, t time.Time, region string, stype serviceType) []byte {

func (c ChecksumInfo) MarshalJSON() ([]byte, error) {
	info := checksumInfoJSON{
		Name:      fmt.Sprintf("part.%d", c.PartNumber),
		Algorithm: c.Algorithm.String(),
		Hash:      hex.EncodeToString(c.Hash),
	}
	return json.Marshal(info)
}

// UnmarshalJSON - custom checksum info unmarshaller
func (c *ChecksumInfo) UnmarshalJSON(data []byte) error {
	var info checksumInfoJSON

		return
	}

	// Call site replication hook.
	//
	// We encode the xml bytes as base64 to ensure there are no encoding
	// errors.
	cfgStr := base64.StdEncoding.EncodeToString(configData)
	replLogIf(ctx, globalSiteReplicationSys.BucketMetaHook(ctx, madmin.SRBucketMeta{
		Type:       madmin.SRBucketMetaTypeVersionConfig,
		Bucket:     bucket,
		Versioning: &cfgStr,
		UpdatedAt:  updatedAt,

		return
	}

	// Call site replication hook.
	//
	// We encode the xml bytes as base64 to ensure there are no encoding
	// errors.
	cfgStr := base64.StdEncoding.EncodeToString(configData)
	replLogIf(ctx, globalSiteReplicationSys.BucketMetaHook(ctx, madmin.SRBucketMeta{
		Type:      madmin.SRBucketMetaTypeSSEConfig,
		Bucket:    bucket,
		SSEConfig: &cfgStr,
		UpdatedAt: updatedAt,

			if err == nil {
				startTime = time.Unix(0, t)
			}
		}
		uploads = append(uploads, MultipartInfo{
			Bucket:    bucket,
			Object:    object,
			UploadID:  base64.RawURLEncoding.EncodeToString([]byte(fmt.Sprintf("%s.%s", globalDeploymentID(), uploadID))),
			Initiated: startTime,
		})
		populatedUploadIDs.Add(uploadID)
	}

	sort.Slice(uploads, func(i int, j int) bool {

			if len(meta.TaggingConfigXML) > 0 {
				tagCfgStr := base64.StdEncoding.EncodeToString(meta.TaggingConfigXML)
				bms.Tags = &tagCfgStr
				bms.TagConfigUpdatedAt = meta.TaggingConfigUpdatedAt
			}

			if len(meta.VersioningConfigXML) > 0 {
				versioningCfgStr := base64.StdEncoding.EncodeToString(meta.VersioningConfigXML)
				bms.Versioning = &versioningCfgStr

	region := sumHMAC(date, []byte(globalMinioDefaultRegion))
	service := sumHMAC(region, []byte(string(serviceS3)))
	signingKey := sumHMAC(service, []byte("aws4_request"))

	signature := hex.EncodeToString(sumHMAC(signingKey, []byte(stringToSign)))

	// final Authorization header
	parts := []string{
		"AWS4-HMAC-SHA256" + " Credential=" + accessKey + SlashSeparator + scope,
		"SignedHeaders=" + signedHeaders,

		// We use a hash of the plugin URL so that the ARN remains
		// constant across restarts.
		h := sha1.New()
		h.Write([]byte(pluginURL))
		bs := h.Sum(nil)
		resourceID += base64.RawURLEncoding.EncodeToString(bs)
	} else {
		// Check that the roleID is restricted to URL safe characters
		// (base64 URL encoding chars).
		if !validRoleIDRegex.MatchString(roleID) {