SslContextBuilder and Private Key - netty/netty GitHub Wiki

The SslContextBuilder and so Netty´s SslContext implementations only support PKCS8 keys.

If you have a key with another format you need to convert it to PKCS8 first to be able to use it. This can be done easily by using openssl.

For example to convert a non-encrypted PKCS1 key to PKCS8 you would use:

openssl pkcs8 -topk8 -nocrypt -in pkcs1_key_file -out pkcs8_key.pem

For more details please see the OpenSSL docs.