cisco 2950 switch-802.1x

I capture the Network packets when the windows client authorized after input the uesername&password. The 802.1x Network Authentication is the md5-challenge.I get the Random string from the ISA server and the Ciphertext of the password.But I don't know how the windows encrypts the password. Md5 or others? Many thans! If it is the md5,how do it.