For a little background, I am trying resolve an issue with an ISAM (reverse proxy) appliance not being able to connect to a server due to it failing to complete a TLS connection.
A server that is connecting just fine is using ECDHE-RSA-AES256-GCM-SHA384, with peer signing digest of SHA512. This is on a tomcat server.
The on that's having trouble is using ECDHE-RSA-AES256-SHA384, with a peer signing digest of SHA1. This is on Microsoft IIS.
Based on my research, Windows doesn't support ECDHE-RSA-AES256-GCM-SHA384 as a cipher suite (which is fine), but what I don't understand is what the peer signing digest is and why, even with SHA1 hashes disabled on windows, is SHA1 being used.
This may not solve my server issue, but I would like to understand what the peer signing digest is.