func (c credentialHeader) getScope() string {
	return strings.Join([]string{
		c.scope.date.Format(yyyymmdd),
		c.scope.region,
		c.scope.service,
		c.scope.request,
	}, SlashSeparator)
}

func getReqAccessKeyV4(r *http.Request, region string, stype serviceType) (auth.Credentials, bool, APIErrorCode) {
	ch, s3Err := parseCredentialHeader("Credential="+r.Form.Get(xhttp.AmzCredential), region, stype)
	if s3Err != ErrNone {