CertStore certs = CertStore.getInstance("Collection",
new CollectionCertStoreParameters(certList), "BC");
SMIMESignedGenerator gen = new SMIMESignedGenerator();
gen.addSigners(s.getSignerInfos());
gen.addCertificatesAndCRLs(certs);
SMIMESigned newS = new SMIMESigned(gen.generate(msg, "BC"));