throws Exception {
Node issuerNameNode =
certNode.getElementsByTagNameNS(Constants.SignatureSpecNS, "X509IssuerName").item(0);
Node serialNumberNode =
certNode.getElementsByTagNameNS(Constants.SignatureSpecNS, "X509SerialNumber").item(0);
CryptoType cryptoType = new CryptoType(CryptoType.TYPE.ISSUER_SERIAL);
cryptoType.setIssuerSerial(issuerNameNode.getTextContent(),
new BigInteger(serialNumberNode.getTextContent()));
return crypto.getX509Certificates(cryptoType)[0];
}