// preSignV4 presign the request, in accordance with
// http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-query-string-auth.html.
func preSignV4(req *http.Request, accessKeyID, secretAccessKey string, expires int64) error {
	// Presign is not needed for anonymous credentials.
	if accessKeyID == "" || secretAccessKey == "" {
		return errors.New("Presign cannot be generated without access and secret keys")
	}

	region := globalSite.Region

	// AccountOff indicates that credentials are disabled
	AccountOff = "off"
)

// Credentials holds access and secret keys.
type Credentials struct {
	AccessKey    string                 `xml:"AccessKeyId" json:"accessKey,omitempty" yaml:"accessKey"`
	SecretKey    string                 `xml:"SecretAccessKey" json:"secretKey,omitempty" yaml:"secretKey"`