CertificateFactory cf = CertificateFactory.getInstance("X.509");
InputStream in = new ByteArrayInputStream(myHexCert);
Certificate cert = (X509Certificate) cf.generateCertificate(in);

java.security.Signature sig = java.security.Signature.getInstance("1.2.840.113549.1.1.11");
sig.initVerify(cert);
sig.update(myData);
bool verification = sig.verify(mySignedData);