EAP-TTLS on Windows 8 (Build 8250)
The available non-EAP (inner) methods are:
See RFC5281 Section 15.1 for the message sequences in an example that shows CHAP as non-EAP inner.
Looking at Section 11.2, in particular 11.2.3 (MS-CHAP) and 11.2.3 (MS-CHAP v2) it can be seen that based on the use of “ttls challenge” material (Section 11.1) the client generates the Challenge and the Response based on the corresponding MS-CHAP (v2) algorithm.
The EAP methods for the inner are: