CMS_add1_signer
si = CMS_add1_signer(cms, signer, key,
if (pkey && !CMS_add1_signer(cms, signcert, pkey, NULL, flags)) {
rct_si = CMS_add1_signer(cms, signcert, pkey, NULL, flags);
CMS_SignerInfo *CMS_add1_signer(CMS_ContentInfo *cms, X509 *signer,