PKCS7_sign_add_signer
if (PKCS7_sign_add_signer(p7, signer, key,
if (pkey && !PKCS7_sign_add_signer(p7, signcert, pkey, NULL, flags)) {
PKCS7_SIGNER_INFO *PKCS7_sign_add_signer(PKCS7 *p7,
info = PKCS7_sign_add_signer(pkcs7, cert, key, md, 0);