CMSSignedDataGenerator gen = new CMSSignedDataGenerator();
gen.addSigner(_origKP.getPrivate(), _origCert, CMSSignedDataGenerator.DIGEST_SHA1);
gen.addCertificatesAndCRLs(certs);
CMSSignedData sd = gen.generate(msg, true, "BC");
certs = sd.getCertificatesAndCRLs("Collection", "BC");
Iterator it = certs.getCertificates(null).iterator();