val documentToSign: Elem =
      <PatientRecord>
        <Name>John Doe</Name>
        <Account id="acct">123456</Account>
        <Visit date="10pm March 10, 2002">
          <Diagnosis>Broken second metacarpal</Diagnosis>
        </Visit>
        <Sig></Sig>
      </PatientRecord>

val jdkDocumentToSign = xpath.evaluate("//Visit",  documentToSign, XPathConstants.NODE).asInstanceOf[Node]

 // Провайдер XMLDSigRI.
    val pxml = new XMLDSigRI
    val sigFactory: XMLSignatureFactory = XMLSignatureFactory.getInstance("DOM", pxml)

    // signing whole document
    val referenceURI = ""
    val transforms: List[Transform] = List(
      sigFactory.newTransform(Transform.ENVELOPED, null.asInstanceOf[TransformParameterSpec]),
      sigFactory.newTransform(Transforms.TRANSFORM_C14N_EXCL_OMIT_COMMENTS, null.asInstanceOf[XMLStructure])
    )

    // Ссылка на подписываемые данные с указанием алгоритма хеширования.
    val signAlgName = Consts.URI_GOST_SIGN
    val digestAlgName = Consts.URI_GOST_DIGEST
    val ref = sigFactory.newReference(referenceURI, sigFactory.newDigestMethod(digestAlgName, null), transforms.asJava, null, null)

    // Создаем объект SignedInfo с указанием алгоритма подписи.
    val signedInfo = sigFactory.newSignedInfo(sigFactory.newCanonicalizationMethod(CanonicalizationMethod.EXCLUSIVE,
    null.asInstanceOf[C14NMethodParameterSpec]), sigFactory.newSignatureMethod(signAlgName, null), List(ref).asJava)

    val keyInfoFactory: KeyInfoFactory = sigFactory.getKeyInfoFactory
    var keyInfo: KeyInfo = null

    // Создаем X509Data, содержащий сертификат.
    val x509d: X509Data = keyInfoFactory.newX509Data(Collections.singletonList(cert))

    // Создаем KeyInfo и добавляем X509Data в него.
    keyInfo = keyInfoFactory.newKeyInfo(Collections.singletonList(x509d))

    val dsc: DOMSignContext = new DOMSignContext(privateKey, parentSigNodes)

    dsc.setProperty("org.jcp.xml.dsig.internal.dom.SignatureProvider", JCSP.PROVIDER_NAME)

    // Создаем XMLSignature.
    val signature = sigFactory.newXMLSignature(signedInfo, keyInfo)

    // Подписываем.
    signature.sign(dsc)

    val os: OutputStream = new FileOutputStream("Sign.xml")
    val trans: Transformer = TransformerFactory.newInstance.newTransformer
      trans.transform(new DOMSource(jdkWholeDocument), new StreamResult(os))   

2016-06-06 13:36:13 DEBUG r.C.J.d.i.DigesterOutputStream requestId=unknown userId=unknown origin=unknown companyId=unknown success=unknown - Pre-digested input:
2016-06-06 13:36:13 DEBUG r.C.J.d.i.DigesterOutputStream requestId=unknown userId=unknown origin=unknown companyId=unknown success=unknown - <PatientRecord>
        <Name>John Doe</Name>
        <Account id="acct">123456</Account>
        <Visit date="10pm March 10, 2002">
          <Diagnosis>Broken second metacarpal</Diagnosis>
        </Visit>
        <Sig></Sig>
      </PatientRecord>