return cred, ErrNone
	}

	return cred, ErrAccessDenied
}

// Fetch the security token set by the client.
func getSessionToken(r *http.Request) (token string) {
	token = r.Header.Get(xhttp.AmzSecurityToken)
	if token != "" {
		return token
	}
	return r.Form.Get(xhttp.AmzSecurityToken)
}

// Fetch claims in the security token returned by the client, doesn't return