gen.addSigner(_signKP.getPrivate(), _signCert, SMIMESignedGenerator.DIGEST_SHA1, new AttributeTable(signedAttrs), null);
gen.addCertificatesAndCRLs(certs);
MimeBodyPart res = gen.generateEncapsulated(msg, "BC");
assertEquals("application/pkcs7-mime; name=smime.p7m; smime-type=signed-data", res.getHeader("Content-Type")[0]);
assertEquals("attachment; filename=\"smime.p7m\"", res.getHeader("Content-Disposition")[0]);
assertEquals("S/MIME Cryptographic Signed Data", res.getHeader("Content-Description")[0]);
}