Because I couldn't find any discussion about Schannel development, I started a feature suggestion on the Windows User Voice site for Microsoft to add ChaCha20-Poly1305 cipher suites to Schannel, mostly for the benefit of mobile visitors to IIS websites, but also to help Windows phones and tablets that don't have integrated CPU extensions for GCM encryption (improved speed and reduced power consumption).
It's frustrating to be a security-focused IIS website administrator. Schannel is a "black box" that we can't tinker with or extend ourselves, and support for modern ciphers has been lagging behind other website and client software (it looks like we'll at least finally get strong and forward secret ECDHE_RSA + AES + GCM suites with Windows 10 and Server vNext/2016). The methods for configuring cipher suite orders and TLS versions could really use a rethink too (thank goodness for IISCrypto).
Hi Jamie_E,
May the following article can help you,
Cipher Suites in Schannel
http://msdn.microsoft.com/en-us/library/windows/desktop/aa374757%28v=vs.85%29.aspx
Managing SSL for a Client Access Server
http://technet.microsoft.com/en-us/library/bb310795.aspx
Configuring Secure Sockets Layer in IIS 7
http://technet.microsoft.com/en-us/library/cc771438(WS.10).aspx
How to enable Schannel event logging in IIS
https://vkbexternal.partners.extranet.microsoft.com/VKBWeb/?portalId=1#
How to restrict the use of certain cryptographic algorithms and protocols in Schannel.dll
http://support.microsoft.com/kb/245030/EN-US
Im glad to be of help to you!