enveloped.addTransform(Transforms.TRANSFORM_ENVELOPED_SIGNATURE);
signature.addDocument("", enveloped);
SecretKey secretKey = this.generateKeyFromPass(signature, password);
signature.sign(secretKey);
} catch (XMLSignatureException ex) {
throw new IOException(ex.getMessage());
} catch (XMLSecurityException ex) {
throw new IOException(ex.getMessage());
}