}

		// Retrieve the STS account's credential object.
		u, ok := globalIAMSys.GetUser(ctx, value.AccessKeyID)
		if !ok {
			c.Fatalf("Expected to find user %s", value.AccessKeyID)
		}

		if u.Credentials.AccessKey != value.AccessKeyID {
			c.Fatalf("Expected access key %s, got %s", value.AccessKeyID, u.Credentials.AccessKey)
		}

		// Retrieve the credential's claims.

// 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()