Motivation:
BoringSSL allows to customize the way how key signing is done an even offload it from the IO thread. We should provide a way to plugin an own implementation when BoringSSL is used.
Modifications:
- Introduce OpenSslPrivateKeyMethod that can be used by the user to implement custom signing by using ReferenceCountedOpenSslContext.setPrivateKeyMethod(...)
- Introduce static methods to OpenSslKeyManagerFactory which allows to create a KeyManagerFactory which supports to do keyless operations by let the use handle everything in OpenSslPrivateKeyMethod.
- Add testcase which verifies that everything works as expected
Result:
A user is able to customize the way how keys are signed.