X509_to_X509_REQ
if ((rreq = X509_to_X509_REQ(template_cert, NULL, NULL)) == NULL)
X509_REQ *req = X509_to_X509_REQ(cert, NULL, NULL);
X509_REQ *X509_to_X509_REQ(X509 *x, EVP_PKEY *pkey, const EVP_MD *md);