Different RSA keySize setting for root certifcates

[Benjamin Marwell]

Dear security-dev list members!

Recently I was thinking I could raise the RSA restrictions to >= 4096,
i.e. setting something like this:

	jdk.tls.disabledAlgorithms=..., RSA keySize < 4096

However, while all TLS server certificates do have RSA 4096 (or EC) 
nowadays, root certificates are another game.
They often still use RSA 2048, and this is perfectly fine, according to 
most comments by security researchers I have seen.
So, applying this setting will lead to most server connections being 
rejected.

Now, I wonder if we could have two settings.
We already have `jdk.security.caDistrustPolicies`.
Maybe we could have `jdk.tls.disabledCaAlgorights` which defaults to 
`jdk.tls.disabledAlgorithms` if not specified.
Or maybe something along those lines.

This way, we could enforce RSA4096 server connections via TLS,
but still allow those certs to be signed with a root CA that still uses 
RSA2048.

I know, this is of limited use in most environments, but I still wanted 
to introduce you to this idea.

Please let me know if this is a sensible request.

Thanks!
- Ben