PGPPublicKeyEncryptedData pbe = (PGPPublicKeyEncryptedData) enc.get(0);
InputStream encData = pbe.getDataStream(key, "BC");
pgpFactory = new PGPObjectFactory(encData);
PGPCompressedData comData = (PGPCompressedData) pgpFactory.nextObject();
pgpFactory = new PGPObjectFactory(comData.getDataStream());
Object object = pgpFactory.nextObject();
PGPOnePassSignature signature;
if (object instanceof PGPOnePassSignatureList) {
signature = getSignature(exchange, (PGPOnePassSignatureList) object);