SSL_CTX_use_PrivateKey
if (SSL_CTX_use_PrivateKey(ctx, key) <= 0) {
int SSL_CTX_use_PrivateKey(SSL_CTX *ctx, EVP_PKEY *pkey);
ret = SSL_CTX_use_PrivateKey(ctx, pkey);
ret = SSL_CTX_use_PrivateKey(ctx, pkey);
if (SSL_CTX_use_PrivateKey(ssl_ctx, pkey) != 1) {